scientific committee · theory and fundamental electrochemistry, te ... regarding ion transfers at...

SCIENTIFIC COMMITTEE Iluminada Gallardo Aránzazu Heras José Solla Ignacio Sirés Vicente Montiel Manuel Blázquez Enric Brillas Simonetta Palmas Sandra Rondinini Onofrio Scialdone Francesco Di Franco Michele Pavone

ORGANIZING COMMITTEE

Chair: José M. Pingarrón

Secretary: Susana Campuzano

Members: Paloma Yáñez-Sedeño María Pedrero Araceli González-Cortés Emiliano Martínez-Periñán Verónica Serafín Gonzalo Martínez-García Esther Sánchez-Tirado Sara Guerrero Eloy Povedano Alejandro Valverde-de la Fuente Christian Durante Claudio Gerbaldi

INDEX

PLENARY LECTURES ..................................................................................... 4

KEYNOTE LECTURES ..................................................................................... 8 Analytical electrochemistry, AE ...................................................................................................... 9 Bioelectrochemistry, BE ................................................................................................................ 13 Electrochemical energy storage & conversion, EE ........................................................................ 14 3RD E3 MEDITERRANEAN SYMPOSIUM: Electrochemistry for Environment and Energy, E3MS . 17 Electrochemical process technology & engineering, EP ............................................................... 20 Material electrochemistry, MaE ................................................................................................... 22 Theory and fundamental electrochemistry, TE ............................................................................ 23

ORAL COMMUNICATIONS .......................................................................... 25 Analytical electrochemistry, AE .................................................................................................... 26 Bioelectrochemistry, BE ................................................................................................................ 40 Electrochemical energy storage & conversion, EE ........................................................................ 44 3RD E3 MEDITERRANEAN SYMPOSIUM: Electrochemistry for Environment and Energy, E3MS . 60 Electrochemical process technology & engineering, EP ............................................................... 76 Material electrochemistry, MaE ................................................................................................... 82 Theory and fundamental electrochemistry, TE ............................................................................ 90

POSTER COMMUNICATIONS ........................................................................ 95 Analytical electrochemistry, AE .................................................................................................... 96 Bioelectrochemistry, BE .............................................................................................................. 109 Electrochemical energy storage & conversion, EE ...................................................................... 111 3RD E3 MEDITERRANEAN SYMPOSIUM: Electrochemistry for Environment and Energy, E3MS 119 Electrochemical process technology & engineering, EP ............................................................. 134 Material electrochemistry, MaE ................................................................................................. 142 Theory and fundamental electrochemistry, TE .......................................................................... 148

AWARDS WINNER LECTURES ..................................................................... 150 “Investicación científica” ............................................................................................................. 151 “Jóvenes investigadores” ............................................................................................................ 152 “III Antonio Aldaz” ....................................................................................................................... 153

PhD PROJECTS ........................................................................................... 154

END MASTER THESIS ................................................................................. 163

PLENARY LECTURES

PL-1

5

OPERANDO METHODS FOR THE STUDY OF ENERGY MATERIALS

Héctor D. Abruña

Department of Chemistry & Chemical Biology, Cornell University, Ithaca, New York, USA

[email protected]

Keywords: energy materials, fuel cells, batteries, operando methods

This presentation will deal with the development of operando methods for the study and characterization of fuel cell and battery materials. The presentation will begin with a brief overview of the methods employed. Particular emphasis will be placed on the use of X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS) X-ray microscopy and tomography and transmission electron microscopy (TEM) under active potential control. The utility of these methods will be illustrated by selected examples including electrocatalysts for the oxygen reduction reaction and spectroscopic studies of Li/S

batteries and Li metal deposition and dendritic growth. The use of operando TEM will be illustrated by studies of fuel cell catalyst degradation and coalescence and lithiation/de-lithiation dynamics of LiFePO4 via energy-filtered TEM.

The presentation will conclude with an assessment of future directions.

PL-2

6

Functional Mesoporous Materials in Electrochemistry, Analytical Chemistry and Environment: Special Focus on Oriented Nanoporous Silica Thin Films

Alain Walcarius

Laboratoire de Chimie Physique et Microbiologie pour les Matériaux et l’Environnement, LCPME, UMR7564 CNRS – Université de Lorraine, 405 rue de Vandoeuvre, 54600 Villers-les-Nancy, France.

E-mail: [email protected]

Keywords: mesoporous silica, thin films on electrode, permselective coatings, sensors Since the discovery of ordered mesoporous silicates, i.e. hard materials prepared from soft templates, this family of solids well-organized at the nanoscale has been largely exploited in electrochemistry [1], particularly for electrochemical sensing and biosensing [2,3]. The reasons beyond such success have to be found in their attractive features, including a periodic and widely open structure, great porosity and large specific surface area with narrow pore size distribution, good mechanical stability and ease of modification with a wide range of organo-functional groups. After a brief presentation of these materials and their interest in electroanalysis, this lecture will focus on one illustrative example, dealing with the modification of electrodes with mesoporous silica films exhibiting unique vertical pore orientation. Ordered mesoporous films with mesochannels oriented perpendicular to a solid surface can be generated by electrochemically assisted self-assembly [4]. The method combines the electrochemically driven self-assembly of surfactants onto an electrode surface and sol-gel electro-assisted deposition by electrochemical pH tuning at the electrode/solution interface to induce condensation of the precursors in a controlled way [5]. Such vertical orientation of small pores (2-3 nm in diameter) induces fast mass transport rates, which can be exploited for electroanalytical purposes. These films exhibit permselective properties based on charge [6] and size selectivity [7], with potential applications in molecular sieving [7], cations sensing [8], or as antifouling surfaces [9]. Once functionalized with redox-active moieties, which can be achieved by combining electrogeneration and click chemistry [10], they enable long-range charge transport via electron hopping [11], possible detection of size-excluded redox probes [7], or indirect amperometric detection of non-electroactive species [12]. References [1] A. Walcarius, Chem. Soc. Rev. 2013, 42, 4098. [2] A. Walcarius, Electroanalysis 2015, 27, 1303. [3] M. Etienne, L. Zhang, N. Vilà, A. Walcarius, Electroanalysis 2015, 27, 1303. [4] A. Walcarius, E. Sibottier, M. Etienne, J. Ghanbaja, Nature Mater. 2007, 6, 602. [5] A. Goux, M. Etienne, E. Aubert, C. Lecomte, J. Ghanbaja, A. Walcarius, Chem. Mater. 2009, 21, 731. [6] C. Karman, N. Vilà, A. Walcarius, ChemElectroChem 2016, 3, 2130. [7] N. Vilà, E. André, R. Ciganda, J. Ruiz, D. Astruc, A. Walcarius, Chem. Mater. 2016, 28, 2511. [8] T. Nasir, G. Herzog, L. Liu, M. Hébrant, C. Despas, A. Walcarius, ACS Sensors 2018, 3, 484. [9] M. B. Serrano, C. Despas, G. Herzog, A. Walcarius, Electrochem. Commun. 2015, 52, 34. [10] N. Vilà, J. Ghanbaja, E. Aubert, A. Walcarius, Angew. Chem. Int. Ed. 2014, 53, 2945. [11] N. Vilà, A. Walcarius, Electrochim. Acta 2015, 179, 304. [12] C. Karman, N. Vilà, C. Despas, A. Walcarius, Electrochim. Acta 2017, 228, 659.

PL-3

7

ADVANCES IN THE STUDY OF CHARGE TRANSFER PROCESSES AT STATIC AND DYNAMIC MICRO- AND NANO-INTERFACES

Ángela Molina

International Regional Campus of Excellence 'Mare Nostrum', Universidad de Murcia, Spain. E-mail: [email protected]

Keywords: Voltammetry; Reaction mechanisms; Microelectrodes; Liquid|liquid microinterfaces; Spectroelectrochemistry A quite comprehensive overview will be given on the analytical theoretical framework developed over years for the study of heterogeneous charge transfer reactions with small-size metal|liquid and liquid|liquid interfaces. With respect to electrode processes, a number of reaction mechanisms are considered, including solution-phase and surface-confined electron transfers with none, one or multiple coupled chemical reactions of any kinetics, from slow rate constants to equilibrium conditions. The voltammetric responses are studied as a function of the electrode size and shape that affect the mass transport conditions from linear (macro-electrodes) to highly-convergent diffusion (micro- and nano-electrodes). For the first time, such conditions are demonstrated to affect the thickness of the region where the chemical equilibria are broken by the application of the electrical perturbation (the so-called reaction layer) and suitable expressions are derived for the most common microelectrode geometries [1]. The theoretical results have been applied, among other systems, to the experimental determination of ion pairing constants by combining electrochemical measurements and DFT calculations, which have an effect on the catalytic activity of polyoxometalates [2]. Moreover, not only the current response has been analyzed but also the concentration profiles of the individual species, which has enabled us to apply the results to the quantitative study of reaction mechanisms via spectroelectrochemistry. Regarding ion transfers at polarized liquid|liquid interfaces [3], the complex situation of microinterfaces supported at capillaries, pipets and pores has been tackled. In these systems the mass transport either side of the interface are markedly different. This fact leads to unusual voltammetric behaviours that can be described and interpreted correctly and easily with the analytical expressions presented in this communication.

References [1] A. Molina, E. Laborda, J. González, Electrochem. Comm. 71 (2016) 18-22 [2] J.M. Gómez-Gil, A. Molina, E. Laborda, J. González, R.G. Compton, J. Phys. Chem. C 121 (2017) 26751-26763 [3] A. Molina, E. Laborda, J.M. Olmos, E. Millán-Barrios, Anal. Chem. 90 (2018) 3402-3408 Acknowledgments The author thanks the research group 'Theoretical and Applied Electrochemistry' (University of Murcia). Financial support of Fundación Séneca de la Región de Murcia (Project 19887/GERM/15) and Ministerio de Economía y Competitividad (Projects CTQ-2015-65243-P and CTQ-2015-71955-REDT).

KEYNOTE LECTURES

AE-KN1

9

ELECTROCHEMICAL STRATEGIES FOR THE AUTHENTICATION OF FOODS BASED ON PHENOLIC COMPOUNDS FINGERPRINTS

J.M. Díaz-Cruz1*, M. Aragó1, C. Sánchez1, A. Gámez1, C. Pérez-Ràfols1, O. Núñez1,2, X.

Cetó1, N. Serrano1, C. Ariño1, M. Esteban1

1 Department of Chemical Engineering and Analytical Chemistry, Faculty of Chemistry, University of Barcelona. Martí i Franquès, 1-11, 08028, Barcelona.

2 Serra Húnter Fellow, Generalitat de Catalunya, Spain. *e-mail: ([email protected])

Keywords: Food authentication, polyphenols, fingerprint, voltammetric electronic tongues, liquid chromatography with amperometric detection, chemometrics. Characterization, classification and authentication of food products is a matter of increasing interest due to their strong social, economic and health implications. In recent years, diets rich in fruits and vegetables have become popular due to the presence of phenolic substances, which are powerful antioxidants quite active against cardiovascular and cancer diseases. But, besides these health benefits, the distribution of phenolic substances in foods can be related to specific varieties, processing technologies and production regions. Foods under a protected designation of origin (PDO) status are subjected to quality checks carried out by the technical services of the respective regulatory boards to assess that producers comply with the specific technical production conditions along the whole food chain, from the farms to the market [1]. Nevertheless, despite those controls, there is a demand of new analytical low-cost methods, with high sensitivity, good selectivity and fast response to assess the fulfilment of quality control standards and authenticity (i.e. fraud detection), either during or after the food elaboration. This is especially critical as there are not specific compounds primarily related to PDO label. Therefore, quality control approaches are shifting from compound-oriented to pattern-oriented strategies, using the whole analytical profile and analyzing it by means of pattern recognition methods to extract characteristic fingerprints. For this purpose, electroanalysis takes advantage of the electroactive character of phenolic substances and offers two especially promising tools for food authentication. On the one hand, voltammetric electronic tongues yield an oxidative current fingerprint as a function of the applied potential and, on the other hand, liquid chromatography with electrochemical detection provides a fingerprint based on retention times (i.e., with some degree of separation of the compounds involved). Chemometric methods like principal component analysis (PCA) or linear discriminant analysis (LDA) can be very helpful to classify and authenticate food samples by using such characteristic fingerprints. In these regards, the use of such methodologies to the authentication of Spanish paprika samples is proposed.

[1] P. Lucci, J. Saurina, O. Núñez, TrAC Trends Anal. Chem. 88 (2017) 1-2

mailto:[email protected]

AE-KN2

10

ISOTHERMAL APTAMER ELONGATION FOR SENSITIVE TUMOR BIOMARKER ELECTROCHEMICAL DETECTION

N. de-los-Santos-Álvarez*, R. Lorenzo-Gómez, R. Miranda-Castro, M.J. Lobo-Castañón

Departamento de Química Física y Analítica. Universidad de Oviedo. Av. Julián Clavería 8, 33006

Oviedo *[email protected]

Keywords: aptamer, isothermal amplification, cancer biomarker Glycosylation is one of the hallmarks of cancer. Currently, most of biomarkers approved for clinical usage are glycoproteins or directly the glycan moiety of proteins. Under normal physiologic conditions there is a great heterogeneity in glycosylation of a single protein but the distribution of glycoforms is stable and reproducible [1]. Glycan expression is disturbed during malignant transformation leading to aberrant glycosylation patterns. However, only the total protein level is clinically monitored except in the case of α-fetoprotein, where the ratio between a specific glycosylated fragment and the total protein is a better biomarker to predict the risk of developing hepatocellular carcinoma. The detection of specific glycan modification is a promising strategy to find most sensitive and selective biomarkers. However, receptors with such powerful discrimination ability are not available. The exquisite selectivity and small size of aptamers can fill this gap, but the quantification methods must be extremely sensitive to sense a portion of a low-abundant protein [2]. Aptamer frequently replace antibodies in enzyme-amplified binding assays, but the sensitivity achieved might not be enough for such demanding applications. As nucleic acids, aptamer can be elongated using the large variety of molecular biology tools. Among them, isothermal amplifications are gaining importance because they help simplify the design of integrated assay platforms to minimize sample manipulation and the risk of contamination. In this work, we show the amplification power of isothermal methods, the simplicity of aptamer and probes design and the careful optimization of operational parameters that lead to a minimum consumption of relatively expensive reagents such as enzymes or modified nucleotides in amplification assay times as short as 15 min. References [1] U. Kuzmanov, H. Kosanam, E. P. Diamandis, The sweet and sour of serological glycoprotein tumor biomarker quantification, BMC Medicine, 11(1), 2013, 31. [2] A. Díaz-Fernández, R. Miranda-Castro, N. de-los-Santos-Álvarez, M.J. Lobo-Castañón, Post-translational modifications in tumor biomarkers: the next challenge for aptamers? Anal. Bioanal. Chem., 410, 2018, 2059. Acknowledgments R.L.G thanks Spanish Government for a predoctoral FPU grant. This work has been financially supported by Spanish Government (project CTQ2015-63567-R)

AE-KN3

11

NON-ENZYMATIC HYDROGEN PEROXIDE SENSOR BASED ON POLY(AZURE A) MODIFIED SCREEN-PRINTED CARBON ELECTRODES

E. Valero1*, M. I. González Sánchez1, B. Gómez Monedero1, R. Jiménez Pérez1, J.

Agrisuelas2

1Department of Physical Chemistry, Superior Technical School of Industrial Engineering, University of Castilla-La Mancha, Campus Universitario s/n, 02071, Albacete, Spain.

2Department of Physical Chemistry, Faculty of Chemistry, University of Valencia, C/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.

*e-mail: [email protected]

Keywords: Hydrogen peroxide; conducting polymers; poly(azure A); sodium dodecyl sulfate; electrochemical sensor; disposable screen-printed electrodes The production of reactive oxygen species (ROS) in living organisms is closely related to oxidative stress. This makes it important to develop highly sensitive methods for the detection of H2O2, the most stable ROS. Many previous works have focused on the development of enzyme-based H2O2 sensors, which may be restricted in practical application owing to the limited lifetimes, high costs, low stability and denaturation of enzymes. An effective way to overcome these disadvantages is to develop non-enzymatic sensors. For example, Pt-based electrodes are commonly used for that purpose [1,2], because this metal is a good catalyst for H2O2 decomposition. In the present communication, poly(azure A) (PAA) films were electrosynthetized in presence of different doping anions on disposable screen-printed carbon electrodes (SPCEs). The modified electrodes showed improved electrocatalytic activities towards H2O2 oxidation compared to that of a bare SPCE. In particular, the insertion of dodecyl sulfate anions inside PAA films provided a special sensitivity to the electrocatalysis of H2O2, which endowed these electrodes with promising analytical features for H2O2 quantification. We obtained a wide linear response for H2O2 within a range of 5 µM to 3 mM and a limit of detection of 1.43 µM ± 0.10 µM (signal-to-noise ratio of 3). Furthermore, sensitivity was 72.4 ± 0.49 nA µM-

1 cm-2 at a relatively low electrocatalytic oxidation overpotential of 0.5 V vs Ag. The applicability of this boosted system was tested by the analysis of H2O2 in commercial samples of a hair lightener and an antiseptic and was corroborated by spectrophotometric methods.

[1] M.I. González-Sánchez, H. González-Maciá, M.T. Pérez-Prior, E. Valero, J.T. Hancock, A. Killard. Plant Cell & Environment 2013, 36, 869-878. [2] J. Agrisuelas, M.I. González-Sánchez y E. Valero. Sensors & Actuators B: Chemical 2017, 249, 499- 505.

This work was supported by the Spanish Ministry of Economy and Competitiveness [Grant No. BFU2016-75609-P] (cofounded with FEDER funds, EU). BGM is a post-doctoral research fellow of the Youth Employment Initiative (JCCM, Spain, cofounded with ESF funds, EU).


AE-KN4

12

DOUBLE PULSE VOLTAMMETRIC STUDY OF THE IT-CEQC MECHANISM UNDERLYING THE OXYGEN REDUCTION AND HYDROGEN EVOLUTION

REACTIONS AT LIQUID/LIQUID INTERFACES

E. Laborda1, E. Torralba2, M. López-Tenés1, A. Molina*1

1 International Regional Campus of Excellence ‘Campus Mare Nostrum’, Universidad de Murcia, Spain 2 Université Paris Est, ICMPE (UMR 7182), CNRS, UPEC, F-94320, Thiais, France


Keywords: Liquid/liquid interfaces; IT-CeqC mechanism; RPV; DDPV; HER/ORR

The reductions of oxygen (ORR) and protons (HER) at soft interfaces assisted by different organic-phase electron donors have been intensively investigated in the past [1,2]. Such effort is justified by the interest and impact of ORR and HER in biology as well as in green energy technologies. As a first approach, the mechanisms proposed for the ORR and HER reactions can be reduced to that given in Figure 1 where the transfer of protons from an aqueous to an organic phase is assisted by species L (an electron donor) and the protonated form HL+ further reacts towards species Y, which corresponds to H2 under anaerobic conditions and to H2O2 in the presence of oxygen.

Figure 1. Schematic view of the IT-CC mechanism at liquid|liquid interfaces

In this work [3], simple analytical equations, diagnosis criteria and procedures for quantitative studies are given for the characterization of the IT-CeqC mechanism at ITIES by double pulse techniques: reverse pulse voltammetry (RPV), differential double pulse voltammetry (DDPV) and double pulse chronoamperometry. Eccentric behaviours of the signals are revealed, as well as procedures for the elucidation of the reaction mechanism and the determination of the chemical kinetics and thermodynamics from experimental RPV limiting currents and cross potentials, and from DDPV peak potentials. These results can assist the study of the HER/ORR biphasic reactions, evaluating the activity of electron-donor species and the performance of the global process, which can be limited by the chemical kinetics of formation of species Y and/or by the rate of diffusion towards the interface.

References [1] I. Hatay, B. Su, F. Li, R. Partovi-Nia, H. Vrubel, X. Hu, M. Ersoz, H.H. Girault, Angew. Chem. 121 (2009) 5241-5244. [2] A. Trojánek, J. Langmaier, Z. Samec, Electrochim. Acta (2012) 457-462. [3] E. Torralba, M. López-Tenés, E. Laborda, A. Molina, Electrochimica Acta 265 (2018) 638-650

Acknowledgements The authors appreciate the support of the Fundación Séneca (19887/GERM/15) and the Ministerio de Economía y Competitividad (CTQ-2015-65243-P and CTQ-2015-71955-REDT). E.T. also thanks the University of Murcia (R-604/2016) for the postdoctoral contract awarded.


BE-KN1

13

VISUALIZING BIOCATALYTIC ACTIVITY AT SINGLE LACTATE OXIDASE MOLECULES USING NANOSCALE SCANNING ELECTROCHEMICAL MICROSCOPY

E. Lorenzo1,2,5*, J. M. Abad 1, A. Y. Tesio 3, E. Martínez-Periñán 4 and F. Pariente 1,2,5

1Departamento de Química Analítica y Análisis Instrumental, 2Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain, 3Centro de Investigación y Desarrollo en Materiales Avanzados y Almacenamiento de Energía de Jujuy-CIDMEJu (CONICET-Universidad Nacional de Jujuy), Centro de Desarrollo Tecnológico General Savio, Av. Martijena s/n, 4612-Palpalá, Jujuy, Argentina, 4Departamento de Química Analítica, Universidad Complutense de Madrid, Ciudad Universitaria 28040 Madrid, Spain, 5Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Campus UAM, Cantoblanco, 28049 Madrid, Spain.

*e-mail: [email protected] Keywords: Nanoscale SECM, Single Lox molecule, Biocatalytic activity Scanning electrochemical microscopy represents a powerful tool for electro(chemical) characterization of surfaces, however its applicability has been limited majority at microscale spatial resolution and the greatest challenge has been the scaling-down to the nanoscale by fabrication and use of nanometer-sized tips. The aim of this work has been focused on showing the potential use of this technique when nanotips are employed as imaging probes. Hence, Pt nanoelectrodes with nanometric electroactive area have been fabricated and employed for imaging the bioelectrocatalytic activity of single Lactate Oxidase molecule covalently attached to a gold surface. The system allows also imaging of distribution of gold nanoparticles (AuNPs) deposited on gold surfaces achieving single nanoparticle detection. It is noteworthy that the fabricated SECM electrodes have an effective nanometer resolution enabling at this level the topographical imaging of the surface besides to the observation the cross-sectional profile and any sharp changes in the topography, demonstrating that gold nanoparticles attachment is more rapid for surfaces sites on vertexes and edges of the core surface (“defect” sites) than core terrace sites.

EE-KN1

14

Study of the surface and electrochemical properties of novel lithium intercalation compounds used as cathodes in Li-ion batteries

J. A. Coca-Clemente1*, V. Dhanak1, L. J. Hardwick1

1Stephenson Institute for Renewable Energy, Department of Chemistry, University of Liverpool,

Liverpool L69 7ZF, United Kingdom [email protected]

Keywords: galvanostatic cycling, differential capacity, XPS, NMC, Li-ion batteries Surface reactivity plays a major role in the capacity and cycle life of lithium intercalation compounds. Understanding the surface chemistry is critical in developing synthetic methods that allow greater stability within these classes of materials to permit their future commercialisation into applications where long lifetimes are required. X-Ray Photoelectron Spectroscopy (XPS) is a surface sensitive technique and it can quantify both the elements present and their oxidation state. [1-3] Different synthetic routes for LiNi1/3Mn1/3Co1/3O2 have been undertaken and the correlation of the surface chemistry and electrochemical performance investigated (Fig. 1). Additionally, novel lithium intercalation compounds with row 6 transition metals in its structure are being also studied with electrochemical methods, using XPS in order to understand their electrochemical behaviour.

Fig. 1. Galvanostatic cycling and differential capacity of NMC using different synthetic routes. References [1] D. Briggs and J. T. Grant, Surface analysis by Auger and X-ray photoelectron spectroscopy, IM publications, 2003. [2] J. C. Dupin, D. Gonbeau, H. Benqlilou-Moudden, P. Vinatier and A. Levasseur, Thin Solid Films, 2001, 384, 23-32 [3] E. Rossen, C. Jones and J. Dahn, Solid State Ionics, 1992, 57, 311-318


EE-KN2

15

QUATERNIZED POLYBENZIMIDAZOLE-POLY(VINYLBENZYL CHLORIDE) MEMBRANES AS HIGH PERFORMANCE ANION EXCHANGE MEMBRANE FUEL

CELLS

D. Herranz*, R. Escudero-Cid, N. Ming, E. Fatás, P. Ocón

Department of Química Física Aplicada, Universidad Autónoma de Madrid, Madrid (Spain) *e-mail: [email protected]

Keywords: polybenzimidazole, poly(vinylbenzyl chloride), fuel cell, AEMFC Fuel cells with polymer electrolyte anion exchange membranes (AEMFCs) had attracted interest in the last years due to the many advantages they present compared to their counterparts proton exchange membrane fuel cells (PEMFCs). Some of the advantages are the possibility of using free-Pt catalysts with metals like Ag, Ni or Ru and thus lowering the CO poisoning and giving excellent resistance to corrosion. Also, the oxygen reduction reaction (ORR) kinetics are highly enhanced. Apart of common fuels for AEMFCs like hydrogen and methanol, ethanol presents some advantages like been easy to storage and transport and can be produced as a renewable biofuel from fermentation of biomass. There is not yet a standard anion exchange membrane (AEM) since factors like conductivity, stability and water management have to be further improved. In our group new membranes of polybenzimidazole (PBI) crosslinked with poly(vinylbenzyl chloride) (PVBC) have been synthesised. They show good flexibility and resistance and already contain a few quaternary ammonium groups. These groups are very important since they are positive fixed charges in the membrane that allow a good conductivity of the hydroxile anions. To really obtain a relevant degree of quaternization in the membrane, tertiary amines as 1,4-diazabicyclo[2.2.2]octane (DABCO) and trimethyl amine (TMA) have been used. These amines react with the chloride pending groups of PVBC to form the quaternary ammonium groups. Different times of quaternization were studied until optimum performance. Membranes were characterized by techniques like FT-IR, Raman and NMR, different proportions of PBI:PVBC were studied and measured in single cell using ethanol 2M/KOH 2M as fuel and pure oxygen as oxidant. It was found that the membrane PBI:PVBC 1:3 gave the best results. References [1] D.R. Dekel, Journal of Power Sources, 375, 158-169 (2017). [2] Jinkai Hao et al., Journal of Membrane Science, 548, 1–10 (2018). Acknowledgments This work has been partially supported by the Madrid Regional Research Council (CAM) under project S2013/MAE-2882 (RESTOENE-2), by the Spanish Economy and Competitiveness Ministry (MINECO) under project ENE2016-77055-C3-1-R.

EE-KN3

16

MEMBRANE-FREE BATTERY: A PARADIGM SHIFT IN ENERGY STORAGE

Rebeca Marcilla1*, Paula Navalpotro1, Marc Anderson1,2, Jesús Palma1,

1 Electrochemical Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain

2 Department of Civil and Environmental Engineering, University of Wisconsin- Madison, 53706, WI, USA

*[email protected] Keywords: redox flow battery, immiscible electrolytes, organic redox flow battery, membrane-free battery Lately, Redox Flow Batteries have become a flourishing field due to the emergence of new redox chemistries including organic compounds, new electrolytes and innovative designs. We introduce here a revolutionary but simple concept of Membrane-Free Flow battery based on the use of immiscible redox electrolytes. These electrolytes spontaneously form a biphasic system whose interphase functions as a “natural” barrier making unnecessary the use of any membrane. Moreover, we substitute the currently used vanadium compounds by organic redox molecules that are abundant, low cost and environmentally friendly. Therefore, this new battery concept is targeted towards solving some of the limitations of current RBFs such as the dependence on expensive and corrosive metallic salts and, most of all, obviate the need for expensive and poorly performing ion-selective membranes. We demonstrate that it is possible to store energy efficiently in a biphasic liquid-liquid system that contains redox active organic molecules. Specifically, we confirm that an acidic solution of hydroquinone (H2Q) and a hydrophobic ionic liquid, 1-Butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) containing dissolved parabenzoquinone (pBQ), spontaneously forms a biphasic system that behaves as a battery without the need of any membrane or physical separator [1]. We will also report here that this “Membrane-Free” concept is highly versatile since it can be applied to different types of aqueous and non-aqueous immiscible electrolytes and different organic-inorganic redox couples [2]. References [1] P. Navalpotro, J. Palma, M. Anderson, R. Marcilla, A Membrane-Free Redox Flow Battery with Two Immiscible Redox Electrolytes, Angew. Chemie - Int. Ed. 56 (2017) 12460–12465. [2] P. Navalpotro, J. Palma, M. Anderson, R. Marcilla, Exploring the Versatility of Membrane-Free Battery Concept Using Different Combinations of Immiscible Redox Electrolytes, J. Power Sources (under revision) Acknowledgments MFreeB project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 726217). The results reflect only the authors’ view and the Agency is not responsible for any use that may be made of the information they contain.

E3MS-KN1

17

SCALE-UP OF ELECTROCHEMICALLY-ASSISTED SOIL REMEDIATION PROCESSES:

LESSONS LEARNED

C. Sáez1*, P. Cañizares1, V. Navarro2, M.A. Rodrigo1

1Chemical Engineering Department, University of Castilla-La Mancha, Enrique Costa Novella Building, Av. Camilo José Cela nº 12, Ciudad Real (Spain)

2Geoenvironmental Group, Civil Engineering School, University of Castilla-La Mancha. Ciudad Real, Spain.

* cristina.saez @uclm.es Keywords: electroremediation, permeable reactive barrier, organochlorinated, ZVI, activated carbon. Most of the scientific studies found in the literature nowadays regarding the application of electrochemical technologies for the remediation of polluted soil are carried out at the lab scale and sometimes, the conclusions reached are tried to be extrapolated to full-scale applications without success. Electrochemical soil remediation behaves as a very important and complex mixture of its forming processes, involving not only electrokinetic processes but also electrolytic and ohmic heating processes, being the scale very important to explain the performance of the technology. In this lecture, the relevance of the scale-up is pointed out by comparing the results obtained during the remediation of soil polluted with different chlorinated organics at lab, bench and prototype scales. Likewise, some results about the performance of different technologies, including combination of electrokinetic soil washing with different types of permeable reactive barriers (with GAC, microorganisms or ZVI) are discussed at the light of the influence of the scale-up on the performance of the processes in order to obtain valuable information for real application of the technology. Acknowledgments Financial support from the Spanish Ministry of Economy, Industry and Competitiveness and European Union through project CTM2016-76197-R (AEI/FEDER, UE) is gratefully acknowledged.

E3MS-KN2

18

ELECTROCHEMICAL CONVERSION OF CARBON DIOXIDE TO FORMIC ACID IN A PRESSURIZZED FILTER PRESS CELL

Onofrio Scialdone*, Alessandro Galia, Federica Proietto

Dipartimento dell’Innovazione Industriale e Digitale – Ingegneria Chimica, Gestionale, Informatica

Meccanica. Università degli Studi di Palermo, Viale delle Scienze Ed. 6, Palermo 90128, Italy. *e-mail: [email protected]

Keywords: electrochemical reduction, CO2 reduction, scale-up, tin cathode, pressure, formic acid To limit the negative effect of carbon dioxide as a greenhouse gas, an interesting approach is the utilization of Carbon Capture and Conversion (CCC) methodology, which is focused on the use of CO2 waste as a feedstock to produce added-value products by using the excess electric energy from renewable source [1]. In this framework, an increasing attention has been devoted to the electrochemical conversion of carbon dioxide to formic acid in water [2-4], which is considered one of the more attractive pathway to convert CO2. Since the main hurdle of the CO2 reduction from aqueous solution is the low CO2 solubility in water, in this work, the effect of some operating parameters, including pressure, current density, and flow rate, on the conversion of CO2 at tin flat cathodes to formic acid was studied using a pressurized filter-press cell with a continuous recirculation of the solution (0.9 L). References [1] Ma, S., & Kenis, P. J. Current Opinion in Chemical Engineering, (2013), 2(2), 191-199 [2] A. Del Castillo, M. Alvarez-Guerra, J. Solla-Gullòn, A. Sàez, V. Montiel, A. Irabien, J. CO2 Util. 18 (2017) 222–228 [3] Pérez-Fortes M., Schöneberger J. C., Boulamanti A., Harrison G., & Tzimas E. International journal of hydrogen energy, (2016), 41(37), 16444-16462. [4] Scialdone O., Galia A., Nero G. L., Proietto F., Sabatino S., & Schiavo B. Electrochimica Acta, (2016), 199, 332-341 Acknowledgments University of Palermo is acknowledged for its financial support.

E3MS-KN3

19

SYNTHESIS OF NANOSTRUCTURED TiO2-PANI ELECTRODES FOR PHOTOELECTROCHEMICAL OXIDATION OF PHENOL UNDER SOLAR LIGHT

IRRADIATION

M. Mascia*, L. Mais, S. Palmas, A. Vacca, S. Corgiolu

Università degli studi di Cagliari, Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, via Marengo 2, 09123, Cagliari (Italy)

*e-mail: [email protected] Keywords: Photoelectrocatalysis, Titanium dioxide, Polyaniline, Phenol oxidation One of the main current worldwide concerns is the increase of water pollution by hazardous organic compounds from textile, cosmetic, pharmaceutical industries, agriculture and urban activities. Phenolic compounds have been considered the most common pollutants in industrial wastewater, coming from paper mills, textile and petrochemical industries, paints, etc. Photoelectrocatalytic treatments offer the possibility to remove toxic organic compounds, even at low concentration, thus making photoelectrocatalysis suitable for the last stages of water purification. The present work proposes an innovative TiO2/PANI electrode for photo electrochemical oxidation of organics: the anode was obtained by an oxidation process of Ti foil in a mixture of 0.14 M NH4F in deionised water (10%) and glycerol (90%). The electrodes were then coated with PANI through a layer – by – layer procedure: a surface grafting by reduction of 4-nitrobenzendiazonium salt was followed by reduction of nitro-groups to amino-groups; PANI was electrodeposited on this under-layer. Photoelectrochemical oxidation of phenol, used as model organic compound, was investigated by performing galvanostatic electrolysis of aqueous solutions at two different initial concentrations of the organic compound (15 mg dm-3 and 300 mg dm-3); 0,1 M NaClO4 was used as supporting electrolyte. During experiments, samples of electrolyte were withdrawn for qualitative and quantitative analyses of both the model organic compound and its intermediates originated from synthetic solution. The results obtained for the oxidation of phenol with galvanostatic batch recirculated electrolysis show that the decrease of phenol concentration follows a pseudo-first order kinetics, in all the adopted conditions. However, the removal of the reactant occurs far from the mass transfer control condition. During the oxidation, hydroquinone and oxalic acid have been detected as main intermediates, which are differently distributed, depending on the experimental conditions and kind of electrodes: the relevant data have been modelled assuming an in-series reaction scheme. The kinetic constants for the formation of aromatic and aliphatic intermediates, obtained with NT-PANI, are higher than those obtained with NT, indicating that the presence of PANI allows to a considerable increase in specific reaction rates of all the steps of the process. Acknowledgments: This activity is supported by Fondazione di Sardegna, Project NAMEFOAMS, F72F16003180002.

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ELECTROCHEMICAL VALORISATION OF CO2 USING GREEN TECHNOLOGIES

S. Mena*, G. Guirado

Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, 08193-Bellaterra, Barcelona, e-mail: [email protected] / [email protected]

Keywords: ionic liquids, green chemistry, electrochemistry, carbon dioxide

Carbon dioxide (CO2) is known as greenhouse gas and is the most important contributor to global warming [1]. Therefore, one of the main challenges is to either eliminate or reuse it through the synthesis of value-added products, such as carboxylated derivatives. One of the most promising approaches for activating, capturing and valorizing CO2 is the use of electrochemical techniques [2]. The benefits of using electrochemical approaches to perform classic chemical reactions in the design of greener and more suitable processes are well established, however the main drawbacks of performing electrochemical reactions are the use of non-volatile organic polar, which are well-known hazardous substances, and the use of supporting electrolytes in high concentration [3]. In this sense, the replacement of electrolytes based on organic solvent by ionic liquids (ILs), which are consider “Green Solvents” would in principle solve this problem.

In this communication, we describe an electrocarboxylation route for synthesizing 4-cyanobenzoic acid by valorizing CO2 through the synergistic use of electrochemical techniques (“Green Technology”) and ILs (“Green Solvents”), two of the major entries in the general Green Chemistry toolkit. The “green” synthesis of those derivatives would open a suitable environmentally friendly process for design of plasticizers based on phthalates derivatives [4].

I

CN+ CO2

HOOC

CNElectrochemical Reduction

Ionic Liquids

References: (1) Nejat, P.; Jomehzadeh, F.; Taheri, M. M.; Gohari, M.; Muhd, M. Z. Renew. Sustain. Energy Rev.

2015, 43, 843–862. (2) Albo, J.; Alvarez-Guerra, M.; Castaño, P.; Irabien, A. Green Chem. 2015, 17 (4), 2304–2324. (3) Frontana-Uribe, B. A.; Little, R. D.; Ibanez, J. G.; Palma, A.; Vasquez-Medrano, R. Green Chem.

2010, 12 (12), 2099-2119. (4) Bocqué, M.; Voirin, C.; Lapinte, V.; Caillol, S.; Robin, J. J. J. Polym. Sci. Part A Polym. Chem.

2016, 54 (1), 11–33. Acknowledgments This work was supported by project CTQ2015-65439-R from the MINECO/FEDER. S.M. thanks the Universitat Autònoma de Barcelona for a predoctoral PIF fellowship.



EP-KN2

21

ESPECTRO-ELECTRO-GRAVIMETRY OF POLY-(NEUTRAL RED): THE ROL OF HYDROGEN ION

F. Vicente*, I. Suarez, J.J. García-Jareño, D. Ferrus, A. Cuenca, J. Agrisuelas

Departamento de Química Física (Universidad de Valencia), Dr. Moliner 50, 46100 Burjassot (Spain)

*e-mail: [email protected] Keywords: espectro-electro-gravimetry, poly.(Neutral Red), hydrogen ion

The scientific interest of electrogenerated polyphenazines is growing as new technological applications are known. This work focuses on the poly- (Neutral Red) [1,2]. The information obtained by electrochemical techniques is of great interest for the development of sensors, charge storage devices, decorative protective paints, membranes and electromechanical devices, as well as to better understand the physical-chemical processes that occur when applying an electrical disturbance to this type of polymeric material.

It has been found that the spectro-electro-gravimetric response is affected by the formation of passive layers of the metal support. However, from obtained data of in situ techniques, it is possible to deconvolute the voltammograms obtained on gold electrodes, for example, by means of Electrochemical Quartz Microbalance EQCM-R to which a spectrophotometer has been coupled, thus being able to separate the contributions of the reductions of the electroactive double bonds of the polymer of the secondary evolution reaction of hydrogen, in addition to also obtaining electromechanical information of the ionic insertion and of the visco-elastic properties of the polymeric film itself. Although the hydrogen ion is not the only counter-ion that participates in the electroneutrality of the PNR and this type of material is a charge accumulator system modulated with the applied potential, the hydrogen ion plays the determining role in the electronic conduction of the polymer and its electrochemical properties in general, as can be seen from the analysis of cross-transfer functions, such as the F(dm/dq) function, which is very useful for characterizing the species that the electroactive film exchanges with the media. References [1] D. Benito, C. Gabrielli, J.J. Garcıa-Jareño, M. Keddam, H. Perrot, F. Vicente, Study by EQCM on

the voltammetric electrogeneration of poly(neutral red). The effect of the pH and the nature of cations and anions on the electrochemistry of the films, Electrochimica Acta. 48 (2003) 4039–4048.

[2] D. Benito, J.J. Garcıa-Jareño, J. Navarro-Laboulais, F. Vicente, Electrochemical behaviour of poly(neutral red) on an ITO electrode, J. Electroanal. Chem. 446 (1998) 47–55.

Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R


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22

SURFACE OXIDATION ENHANCED RAMAN SCATTERING SPECTROELECTROCHEMISTRY

Álvaro Colina1*, Juan V. Perales-Rondón1, Sheila Hernández1, Daniel Martín-Yerga2, Pablo

Fanjul-Bolado2, Aránzazu Heras1

1 Department of Chemistry, Universidad de Burgos, Pza. Misael Bañuelos s/n, E-09001 Burgos, Spain.

2 DropSens, Edificio CEEI, Parque Tecnológico de Asturias, 33428 Llanera, Asturias, Spain. *e-mail: [email protected]

Keywords: EC-SOERS Since the first time Fleishman [1] reported the unusual intense Raman scattering from the adsorbed pyridine on silver roughened electrodes, surface enhanced Raman scattering (SERS) has taken more interest in the scientific community. In the present communication, time-resolved Raman spectroelectrochemistry [2] is used to follow the silver roughening process by using a Raman probe molecule in the electrolytic solution. Under particular experimental conditions, we found a special and unexpected enhancement of the Raman signal at the electrochemical oxidation stage of a silver electrode for different probe molecules. Thus, an equivalent process to SERS is observed, that we have denoted as Surface Oxidation Enhanced Raman Scattering (SOERS). Unlike classical SERS, this effect was only observed during the electrochemical oxidation of the silver electrode surface. Therefore, it has been denoted as Electrochemical-SOERS (EC-SOERS). This effect was potential dependent and exclusively observed for particular experimental conditions. To the best of our knowledge, this is the first time that such behaviour is reported for any Raman probe molecule at anodic potentials. It is noteworthy, that this phenomenon does not match any previous result in classical SERS. A rigorous and systematic study has been done in order to shed more light on the origin of such unexpected Raman signal enhancement. Our work is a first approach to this interesting and unexpected phenomenon that, undoubtedly, should be of interest for a number of researchers. References [1] Fleischmann, M.; Hendra, P. J.; McQuillan, A. J. Chem. Phys. Lett. 1974, 26 (2), 163–166 [2] Ibañez, D.; Fernandez-Blanco, C.; Heras, A.; Colina, A. J. Phys. Chem. C 2014, 118 (40), 23426–23433 Acknowledgments Authors acknowledge the financial support from Ministerio de Economía y Competitividad (Grants CTQ2017-83935-R, CTQ2014-55583-R, and CTQ2015-71955-REDT) and Junta de Castilla y León (Grant BU033-U16). J.V.P-R. thanks JCyL for his postdoctoral fellowship (Grant BU033-U16). S.H. thanks its contract funded by JCyL, the European Social Fund and the Youth Employment Initiative.

TE-KN1

23

INTERFACIAL STUDIES OF NICKEL MODIFIED PT(111) SURFACES. EFFECT ON PZC AND HER.

Francisco J. Sarabia1*, Paula Sebastián-Pascual2, Víctor Climent*3, Juan M. Feliu*4

Departamento de Química-Física Instituto de Electroquímica, Universidad de Alicante, Apdo. 99,.

03080, Alicante *e-mail: [email protected]

Keywords: HER, cyclic voltammetry, CO displacement technique, IRRAS, laser induced temperature jump technique. The hydrogen evolution reaction (HER) constitutes one of the most important reactions in electrochemistry due to the hydrogen utility as energy storage. Therefore, knowing the mechanism of this reaction as well as its pH-dependence is of crucial importance. While the HER on Pt(111) works efficiently in acid media, in alkaline media, however, the reaction needs a considerable overpotential. Nevertheless, it was demonstrated that the presence of Ni(OH)2 adsorbed on Pt(111) highly improves the HER, decreasing the overpotential of this reaction in relation to acid media. The way how low coverages of Ni(OH)2 on the surface improves HER is still under discussion. In this work, the methodology for the preparation of well-defined Ni(OH)2 coverages was revised and the Ni(OH)2-Pt(111)| 0.1M NaOH interface was characterized with cyclic voltammetry, CO displacement technique and FTIRRAS. In addition, and based on the proposal made by Ledezma et. al [1]. to explain the HER in alkaline media, we studied the effect of the different Ni(OH)2 coverages on the interfacial electric field using the laser induced temperature jump technique to determine the potential of maximum entropy [2]. Figure 1. A) Cyclic voltammograms of the Pt(111) surface modified with Ni(OH)2 (dashed line) and without nickel (full line), and B) the same showing the hydrogen evolution reaction. 0,1 M NaOH (pH 13). 50mV/s. The ohmic resistance was corrected for the HER. References [1] I. Ledezma-Yanez, W.D.Z. Wallace, P. Sebastián-Pascual, V. Climent, J.M. Feliu, M.T.M. Koper, Nature Energy, 2 (2017) 17031. [2] N. Garcia-Araez, V. Climent, J. Feliu, Journal of Physical Chemistry C, 113 (2009) 9290-9304.

0.0 0.3 0.6 0.9-90

-60

-30

0

30

60

90

Blank θNi= 0.07

j / µ

A cm

-2

E / V (RHE)

A

-0.3 -0.2 -0.1 0.0 0.1

-10

-8

-6

-4

-2

0

E/V (RHE)

j / m

A cm

-2

Blank θNi= 0.07

B

TE-KN2

24

TAUTOMERISM OF CYTOSINE ADSORBED ON GOLD ELECTRODES. A COMBINED ‘IN-SITU’ ATR-SEIRAS AND DFT STUDY

M. Rueda*, F. Prieto, J. Álvarez-Malmagro

Department of Physical Chemistry. Faculty of Chemistry and Faculty of Pharmacy. University of Seville. C/ Profesor García González nº 1, 41012 Seville (Spain)

*e-mail: [email protected] Keywords: cytosine, DNA bases, ATR-SEIRAS, gold electrodes, DFT, tautomerism Tautomerism of DNA bases plays an important role in the correct genetic replication. In fact, the existence of ‘rare tautomers’ is considered one of the causes of genetic mismatch [1,2]. On the other hand, natural biological membranes are exposed to electric fields of the order of 107-108 V m-1 [3], that can be replicated in the electrode/electrolyte interface. Then, the structural study of adsorbed cytosine on gold electrodes is of fundamental interest as it can provide some knowledge about the influence of the electric field in the tautomeric behaviour of cytosine. Moreover, cytosine coated gold electrodes have potential technological applications as biosensors, due to the recognition capabilities of DNA bases. In aqueous solutions cytosine undergoes two acid/base equilibriums (pKa values 4.5 and 12.2) and can present several tautomeric forms (at least 5 tautomers have been identified [4]). In this work voltammetry and in situ ATR-SEIRAS experiments have been performed at three pH values (in the range from 1 to 11.5) in H2O and D2O solutions about the adsorption of cytosine on Au(111) electrodes and on gold thin film electrodes. The results show the adsorption of the deprotonated cytosine form even at pH bellow the first pKa, as previous adsorption studies have noticed, [5,6]. In this communication, in addition, the results are interpreted on the bases of theoretical DFT spectrums of different tautomeric forms of the adsorbed deprotonated cytosine on clusters of 19 gold atoms and are compared with experimental FT-IR and theoretical DFT spectrums in solution. The results show the preponderance of different tautomers in the adsorbed state than in solution depending not only on the pH of the solution but also on the potential applied to the electrode. References [1] Y. Podolyan, L. Gorb, J. Leszczynski; J. Phys. Chem. A. 109 (2005) 10445–50.

doi:10.1021/jp0550412. [2] W. Wang, H.W. Hellinga, L.S. Beese, Proc. Natl. Acad. Sci. 108 (2011) 17644–17648.

doi:10.1073/pnas.1114496108. [3] J. Lipkowski; Phys. Chem. Chem. Phys. 12 (2010) 13874–13887. doi:10.1039/c0cp00658k. [4] Z. Chen, K.-C. Lau, G.A. Garcia, L. Nahon, D.K. Božanić, L. Poisson, M.M. Al-Mogren, M.

Schwell, J.S. Francisco, A. Bellili, M. Hochlaf; J. Am. Chem. Soc. 138 (2016). doi:10.1021/jacs.6b10413.

[5] T. Wandlowski, D. Lampner, S.M. Lindsay; J. Electroanal. Chem. 404 (1996) 215–226. doi:10.1016/0022-0728(95)04235-0.

[6] K. Ataka, M. Osawa; J. Electroanal. Chem. 460 (1999) 188–196. doi:10.1016/S0022-0728(98)00375-1.

ORAL COMMUNICATIONS

AE-O1

26

MAGNETIC MICROBEADS-BASED BIOSCAFFOLDS FOR DUAL AMPEROMETRIC DETERMINATION AT DIFFERENT MOLECULAR LEVELS OF EMERGING

METASTATIC CANCER BIOMARKERS C. Muñoz-San Martín*, E. Povedano, F.J. Manuel de Villena, M. Pedrero, S. Campuzano,

J.M. Pingarrón Departamento de Química Analítica, Facultad de CC. Químicas. Universidad Complutense de Madrid.

E-28040 Madrid (SPAIN) *e-mail: [email protected]

Keywords: E-cadherin, microRNA-205, magnetosensors, amperometry, SPdCEs. E-cadherin (E-cad) is a protein expressed in all epithelial tissues that forms a molecular barrier able to inhibit proliferation and metastasis of cancer cells. It is strongly expressed in well-differentiated less invasive cancer, leading to a good prognosis. However, its expression is lost in poorly differentiated tumours with invasive behaviour resulting in poor clinical prognosis in patients with carcinoma. On the other hand, microRNA-205 (miRNA-205) is an accepted biomarker of stem cell fate, proliferation and metastasis. Recent findings have demonstrated that weaker miRNA-205 expression is correlated with a loss of E-cad, both sufficient to incite metastatic outgrowth by enabling carcinoma cells to enter a metastasis-initiating state. Therefore, combining results of E-cad protein and miRNA-205 expression has, in fact, been suggested to increase diagnostic specificity and sensitivity for cancer progression and metastasis [1]. With this purpose, this communication will describe the very promising results obtained in the simultaneous detection of E-cad protein and miRNA-205 based on the coupling of the approaches developed for the individual determination of each of the target biomarkers implemented on the surface of magnetic microbeads (MBs) and amperometric transduction at dual screen-printed carbon electrodes (SPdCEs). Under optimal conditions, this dual bioplatform demonstrates a wide linear concentration range (0.50 –100 ng mL-1) and a detection limit as low as 0.16 ng mL-1, well below the optimal cut-off level for the E-cad protein (defined as 10,000 ng mL-1 for soluble E-cad levels in serum [2]), and a dynamic range from 8.2 to 250 pM with a detection limit of 2.4 pM (60 amol) for the synthetic target miRNA without any amplification step [3]. Current efforts are focused on demonstrating the applicability of this handy and reliable bioplatform for the simultaneous and accurate determination of these two biomarkers of great relevance in metastatic processes in serum from cancer patients.

[1] Gregory et al., The miR-200 family and miR-205 regulate epithelial to mesenchymal transition by targeting ZEB1 and SIP1. Nat. Cell. Biol. 10 (2008) 593−601. [2] Chan et al. Early prediction of tumor recurrence after curative resection of gastric carcinoma by measuring soluble E-cadherin. Cancer 104(4) (2005) 740−746. [3] Torrente-Rodríguez et al. Fast electrochemical miRNAs determination in cancer cells and tumor tissues with antibody-functionalized magnetic microcarriers, ACS Sens. 1 (2016) 896−903.

Financial support from the Spanish Ministerio de Economía y Competitividad, CTQ2015-64402-C2-1-R, the Comunidad de Madrid (NANOAVANSENS S2013/MT−3029) and a predoctoral contract from the Spanish Ministerio de Economía y Competitividad (E.P.) are gratefully acknowledged.

AE-O2

27

CARBON NANODOTS FOR THE OXYGEN REDUCTION REACTION ELECTROCATALYSIS

E. Martínez-Periñán1,2, I. Bravo1,3, S.J. Rowley-Neale2,4, E. Lorenzo*1,3, C.E. Banks2,4

1 Departamento de Química Analítica y Análisis Instrumental, Universidad Autónoma de Madrid, 28049, Madrid, Spain, 2Faculty of Science and Engineering, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK, 3IMDEA-Nanoscience, Faraday 9, Campus Cantoblanco-

UAM, 28049 Madrid, Spain, 4Fuel Cell Innovation Center, Manchester Metropolitan University, Chester Street, Manchester M1 5GD, UK *e-mail: [email protected]

Keywords: Carbon nanodots, oxygen reduction reaction, screen-printed electrodes Carbon nanodots (CNDs) are a member of the carbon nanomaterials family, whose electrochemical properties are being currently studied. In this context, two types of carbon nanodots with different surface functional groups, amides (CNDs-CONH2) and carboxylic groups (CNDs-COOH), were synthesized. They were fully characterized by a variety of techniques, such as FTIR, XPS, DLS or TEM. After modification of screen printed carbon electrodes (SPCEs) with CNDs, their electrocatalytic activity towards the oxygen reduction reaction (ORR) was studied both in acidic (0.1 M H2SO4) and basic (0.1 M KOH) media. This reaction has a great importance for the development of proton exchange membrane fuel cells (PEMFCs). Due to the large kinetic barrier of this reaction [1] there is a great interest in the search for new electrocatalysts, which can not only reduce the overpotential and increase the achievable ORR peak current, but also allow the reaction to occur via the desirable 4 electron pathway [2]. In this sense, CNDs modified SPCEs show a higher ORR peak current and reduced overpotential when compared to unmodified SPCEs. Furthermore, CNDs-COOH are found to facilitate the ORR via a near optimal 4 electron pathway in oxygenated 0.1 M KOH. Therefore, CNDs-COOH modified SPCEs could be used as a cathodic electrode for PEMFCs as a cheaper alternative to the traditionally used platinum electrode. References [1] J. H. Zagal, M. T. M. Koper, Angew. Chem. Int. Ed. 2016, 55, 14510–14521. [2] M. Gara, R. G. Compton, New J. Chem. 2011, 35, 2647–2652. Acknowledgments Authors acknowledge funding from the Engineering and Physical Sciences Research Council (Reference: EP/N001877/1), British Council Institutional Grant Link (No. 172726574), Comunidad de Madrid (NANOAVANSENS Program S2013/MIT-3029), Ministerio de Economía y Competitividad (CTQ2014-53334-C2-1-R) and ERDF.

AE-O3

28

ELECTROCHEMICAL BIOSENSORS FOR DETECTION OF TUMOR SUPPRESSOR GENES-SPECIFIC METHYLATIONS IN BIOFLUIDS AND CELLS

E. Povedano*,a E. Vargas,a V. Ruiz-Valdepeñas Montiel,a R. M. Torrente-Rodríguez,a M. Pedrero,a R. Barderas,b P. San Segundo-Acosta,b A. Peláez-García,c M. Mendiola,c D.

Hardisson,c S. Campuzano,a J. M. Pingarróna aDepartamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); bUnidad Funcional de Investigación de Enfermedades Crónicas, Instituto de

Salud Carlos III, 28220 Majadahonda, Madrid (Spain); cDepartment of Pathology, Molecular Pathology and Therapeutic Targets Group, Hospital Universitario La Paz, IdiPAZ, Madrid (Spain).


Keywords: methylated DNA; electrochemical sensor; SPCE; tumor suppressor gene; cancer cells.

DNA methylation is a heritable and reversible process that alters gene expression patterns without modifying the DNA sequence. The inactivation of tumor suppressor genes via hypermethylation of their regulatory regions is one of the most important mechanisms that produce changes in their expression and lead to various types of cancer. For this reason, the detection of altered DNA methylation patterns in the promoter region of cancer related genes is considered a reliable biomarker for early detection, diagnosis, prognosis and therapeutic stratification of cancer [1]. Although current classical methods are effective in studying DNA methylation patterns, they exhibit relatively low sensitivity and high false positive rates, and require expensive instruments and complicated and time-consuming bisulfite and/or amplification pretreatments. This communication describes the development of two very attractive electrochemical biosensing strategies for the simple, sensitive and quick detection of DNA methylation using functionalized magnetic beads (MBs), anti-methylcytosine antibody (anti-5-mC) as affinity bioreceptor, and amperometric detection at SPCEs using the H2O2/HQ system [2]. While one approach involves a sandwich immunosensor using the anti-5-mC immobilized onto HOOC-MBs as capture bioreceptor, the other one employs the anti-5-mC as detector bioreceptor to label the methylated DNA previously captured by a complementary DNA capture probe immobilized on the surface of Strep-MBs. Using as models methylated synthetic sequences of the RASSF1A and MGMT tumor suppressor genes, the newly developed biosensors demonstrated reproducibility throughout the entire protocol, sensitive determination with no need for using amplification strategies, and competitiveness with the conventional ELISA methodology and the few electrochemical biosensors reported so far in terms of simplicity, sensitivity and assay time. Moreover, the DNA sensor exhibited higher sensitivity and selectivity and demonstrated successful applicability for 1 h-analysis in spiked biological fluids and genomic DNA extracted from human glioblastoma cells. These biosensing strategies can serve as a basis for developing easy and affordable tests in an easy-to-use format, not too technically demanding and requiring equipment readily available at most institutions for better outcome of cancer patients. [1] Campuzano and Pingarrón. Electroanal. 2018, in press, DOI: 10.1002/elan.201800004. [2] Povedano et al. Sci. Rep. 2018, under revision.


AE-O4

29

SPECTROELECTROCHEMICAL ANALYSIS OF NEUROTRANSMITTERS AND SIMILAR MOLECULES IN PRESENCE OF INTERFERING SPECIES

J. Garoz-Ruiz*, J. Carazo, P. López, A. Muñoz, F. Olmo, Á. Colina, and A. Heras

Department of Chemistry, Universidad de Burgos, Plaza Misael Bañuelos s/n, E-09001 Burgos, Spain

*e-mail: [email protected] Keywords: spectroelectrochemistry; neurotransmitters; quantitative analysis. UV-Vis absorption spectroelectrochemistry is a very interesting technique for quantitative analysis.1,2 The potential of this technique is based on the spectral signal, concomitantly registered with the electrical response, that is obtained during the electrochemical process. As can be inferred, the selectivity is very high because the presence of two compounds with the same electrochemical and spectroscopic information is practically impossible. Moreover, the spectroelectrochemistry configuration provides another grade of selectivity. Figure 1 is shown to give an idea about the advantages of this technique for analysis. While the electrochemical signal and the spectroscopic response below 330 nm contain information associated with levodopa and uric acid, the absorption band centred at 391 nm is only related to levodopa, being very simple to determine its concentration in mixtures of varying concentrations of both compounds. Using similar methodologies, excellent results are obtained with biomolecules such as dopamine, epinephrine, levodopa or isoprenaline, in presence of different interfering species and using univariate or multivariate analysis.

Figure 1. Cyclic voltammogram (left) and evolution of the absorption spectra with potential during

the oxidation sweep (right) for a solution mixture of levodopa and uric acid (pH 0.8). References: [1] Garoz-Ruiz, J.; Heras, A.; Colina, A. Anal. Chem. 2017, 89 (3), 1815–1822. [2] Zhai, Y.; Zhu, Z.; Zhou, S.; Zhu, C.; Dong, S. Nanoscale 2018, 10 (7), 3089–3111.

Acknowledgments: Financial support from Ministerio de Economía y Competitividad (CTQ2014-55583-R, CTQ2015-71955-REDT, CTQ2017-83935-R) and Junta de Castilla y León (BU033-U16) is gratefully appreciated. Jesus Garoz-Ruiz acknowledges his predoctoral fellowship from Ministerio de Educación, Cultura y Deporte and his postdoctoral contract from Ministerio de Economía y Competitividad (CTQ2014-55583-R).

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30

ACTIVATION OF SCREEN PRINTED CARBON ELECTRODES USING HYDROGEN PEROXIDE

M. I. González-Sánchez*1, B. Gómez-Monedero1, R. Jimenez-Pérez1, J. Agrisuelas2, J.

Iniesta3, E. Valero1

1Departament of Physical Chemistry, School of Industrial Engineers, University of Castilla-La Mancha, Campus Universitario de Albacete, 02071-Albacete, Spain. 2Department of Physical Chemistry, Faculty of Chemistry, University of Valencia, C/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain. 3Department of Physical Chemistry and Institute of Electrochemistry, University of Alicante, 03690, San Vicente del Raspeig, Alicante, Spain.

*[email protected] (corresponding author) Keywords: activation, hydrogen peroxide, electrochemical sensor. Screen printing technology is a widely used technique for the fabrication of miniaturized, sensitive and portable electrochemical sensors. Due to their multiple advantages against conventional electrodes, screen printed electrodes (SPEs) have many applications in electroanalysis fields; for example, clinical tests, environmental analysis or food processing. Sometimes, the electro-transfer properties of these electrodes can be considerably improved by performing different chemical or electrochemical pretreatments. In this work, we propose a facile and effective method for activation of commercial screen-printed carbon electrodes (SPCEs) using H2O2 to enhance sensing performances of carbon ink. The electrochemical activation consists of 25 repetitive voltammetric cycles at 10 mVs-1 using 10 mM H2O2 in phosphate buffer solution (pH 7). This treatment has allowed us to reach a sensitivity of 0.24±0.01 µA µM-1cm-2 for the electroanalysis of H2O2, which is 140 times higher than that of non-treated SPCEs and 6 times more than screen-printed platinum electrodes. Electrode characterization revealed atomic level changes of the electrode surface, with the introduction of new carbon-oxygen groups as responsible for the improvement of electro-transfer properties and sensitivity. The method resulted to be more effective than others previously described in the bibliography. Our electrochemical activation is a promising methodology that may be applicable for activation of commercial carbon inks-based electrodes over different sensing applications, especially for the H2O2 measurement. Acknowledgments This work was funded by the Spanish Ministry of Economy and Competitiveness (MINECO), by the Projects No. BFU2016-75609-P (cofunded with FEDER funds, EU) and CTQ2016-76231-C2-2-R. BGM is a post-doctoral research fellow of the Youth Employment Initiative (JCCM, Spain, cofounded with ESF funds, EU).

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NOVEL ELECTROCHEMICAL IMMUNOPLATFORMS USING GRAPHENE QUANTUM DOTS FOR THE DETERMINATION OF EMERGING CLINICAL

BIOMARKERS

V. Serafín*1, G. Martínez-García1, E. Martínez-Periñan1, A. Valverde de la Fuente1, F. Mollarasouli1,2, K. Asadpour-Zeynali2, P. Yáñez-Sedeño1, S. Campuzano1, J.M. Pingarrón1

1Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid,

Madrid, 28040, Spain. 2Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51666-16471, Iran.

*e-mail: [email protected] Keywords: AXL, IL-13 Rα2, Graphene quantum dots, Grafting, carbon nanotubes (MWCNTs) The incorporation of nanomaterials that play different functions has been extensively explored in the development of electrochemical immunosensors in order to improve their performance. Within this context, Graphene Quantum Dots (GQDs) have demonstrated to be attractive nanomaterials with unique features such as good water solubility, large surface-to-volume ratio, biocompatibility and low toxicity. This work will discuss the basis and main features of very attractive performance immunosensing bioplatforms in which these GQDs have been used both as modifiers of the electrode surface and as carrier tags for signal amplification. Currently, accurate clinical biomarkers determination in minimally invasive samples using simple and rapid methods, compatible with application at different settings, is highly demanded for early diagnosis and improved outcomes. Taking into account the relevant emerging role demonstrated by receptor IL-13 Rα2 and AXL in metastatic colorectal cancer and heart failure, respectively, this work will discuss the preparation of two different immunosensing bioscaffolds, implemented at disposable screen-printed carbon electrodes (SPCEs), for their simple, selective and accurate determination. One of the approaches involves a label-free DPV electrochemical immunosensor for AXL determination prepared by immobilization of the specific anti-AXL antibody onto amine functionalized graphene quantum dots (fGQDs)-modified SPCEs and the other one a novel method for preparation of GQDs/MWCNTs(-HRP)-Anti-IL-13 hybrids, used as carrier tags for signal amplification in the construction of a sandwich immunosensor for amperometric determination of IL-13 Rα2. After careful optimizations of all the experimental variables involved in the functioning of these immunosensing platforms, the characterization of their analytical behaviour demonstrates very attractive performance and successful applicability for the accurate determination of the target biomarkers in relevant clinical samples (serum, whole cells and tissue extracts) after minimal treatments. [1] Mollarasouli et al. Anal. Chim. Acta, 1011, 28-34, 2018. The financial support of projects: Retos Colaboración RTC-2015-4184-1 (cofinanced by the Ministry of Economy and Competitivity and FEDER “una manera de hacer Europa”), CTQ2015-70023-R and CTQ2015-64402-C2-1-R (MINECO Research Projects) and S2013/MT-3029 (NANOAVANSENS Program from the Comunidad de Madrid) are gratefully acknowledged.

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PATTERN MATCHING AS A TOOL FOR THE AUTOMATIC DECONVOLUTION OF HIGHLY OVERLAPPED SIGNALS

J. L. Álvarez2, J. I. Otero1, C. Mozo-Mulero*1, A. Aquino2, J. Carbajo1, J. D. Mozo*1

1Laboratory of Applied Electrochemistry, University of Huelva. Av. 3 de Marzo, s/n, 21071 Huelva, 2Departament of Electronic, Computer Science and Automatic Engineering, University of Huelva,

Campus de La Rábida, 21819 Palos de la Frontera (Huelva) *e-mail: ([email protected])

Keywords: data processing, dopamine analysis, complex signal, deconvolution, automatic initialization When complex samples with several compounds are analyzed, it is possible that the individual contributions to the analytical response appear kind of overlapped. If the characteristics of such individual contributions are used to obtain the analytical information for each compound, they must be extracted from the entire response by read them properly. Such procedure, usually named deconvolution, can be performed with guaranty if each individual contribution is isolated enough to identify its maximum by derivation [1]. If two or more individual contribution are highly overlapped, they appear as an only one signal slightly distorted, so the automatic detection of contributions doesn’t work properly, and a manual initialization is needed. Such case is frequent in chromatographic techniques, as in spectroscopic and electrochemical measurements, so we propose a new method to process complex signals in a flexible and robust manner, regardless of the signal shape or origin. The patter-matching is the basis of such method. To perform, a database with a wide collection of synthetic shapes calculated by adding two individual contributions should be made. The experimental data should be normalized, and their pattern is extracted to compare with the database. Once it is matched, the synthetic individuals are de-normalized and used as the start-point to least-square adjusts to the experimental result. The deconvolution procedure was tested with two referential chemical systems where the overlapping of signals is the main problem found to get results: the In(III)-Cd(II) joint determination by differential pulse polarography (DPP), and the dopamine determination in the presence of uric and ascorbic acids by DPV. A statistic analysis is also performed, showing the robustness and reliability of procedure.

References [1] G. Vivó-Truyols, J.R. Torres-Lapasió, A.M. van Nederkassel, Y. Vander Heyden, D.L. Massart, “Automatic program for peak detection and deconvolution of multi-overlapped chromatographic signals: Part I: Peak detection”, J. Chromat. A 1096(2005)133-145.

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AMPEROMETIC IMMUNOSENSING PLATFORM FOR DETERMINATION OF AN EMERGING BIOMARKER IN ADVANCED COLORECTAL CANCER AND

METASTASIS

A. Valverde-de la Fuente*1, E. Povedano1, P. Yáñez-Sedeño1, M. Garranzo2, R. Barderas2, S. Campuzano1, J.M. Pingarrón1

1Dpto. Química Analítica, Facultad CC. Químicas. Universidad Complutense de Madrid. E-28040

Madrid, Spain. 2CROSADIS, National Institute of Health Carlos III, Majadahonda, E-28222, Madrid, Spain

*[email protected]

Keywords: electrochemical immunosensor; IL-13sRα2; colorectal cancer; raw lysate

Recent findings have demonstrated that highly metastatic colorectal cancer cells express increased levels of both the immunosuppressive cytokine IL-13 and the surface IL-13 receptor (IL-13Rα2) and that IL-13Rα2 is hiperexpressed also in late-stage human colon cancer tissues and correlated with the poor outcome of patients with colon cancer metastasis [1,2]. Methods commonly used for determination of IL-13Rα2 provided qualitative or semi-quantitative (flow cytometry, fluorescent measurements, Western-blotting and immunohistochemical analysis) and quantitative (ELISA kits, based on sandwich formats involving HRP-labeled detector antibodies) determinations. However, most of these methods required multiple steps, are time-consuming and only applicable in centralized settings. Therefore, the development of new methodologies for fast, simple, cost-effective and accurate determination of IL-13Rα2 in clinically relevant samples (metastatic cancer cells or tissues) is highly demanded for early diagnosis, disease follow-up and identification of metastatic processes. This work describes the first amperometric immunosensor reported so far for the determination of soluble IL-13Rα2 (IL-13sRα2). This novel approach involved the formation of sandwich immunocomplexes comprising specific capture anti-IL-13sRα2 (AbC) and biotinylated detector antibodies onto carboxylic-modified magnetic microbeads (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs) using the hydrogen peroxide (H2O2)/hydroquinone (HQ) system. Results achieved with standard solutions in the optimized experimental variables demonstrated the developed immunosensor exhibited a linear calibration plot over the 3.9 to 100 ng mL-1 range, a LOD of 1.2 ng mL-1 and good selectivity against other non-target proteins. It is worth to mention that, in comparison with a commercial ELISA kit involving the same immunoreagents, apart from providing a similar LOD, a linear calibration plot instead of a logarithmic one, and results within half the time, this immunosensor involved portable and cost-effective instrumentation which makes it more easily automated and miniaturized, ideal to perform decentralized and routine analysis of this great emerging relevance biomarker. Furthermore, its successful applicability to provide first quantitative data reported so far regarding IL-13sRα2 expression in raw lysates of colorectal cancer cells is also demonstrated. [1] Barderas, R. et al., Cancer Research 72 (2012) 2780-2790. [2] Bartolomé, R.A., Cancer Research 75 (2015) 2434-2444.

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ELECTROCHEMICAL IMMUNOSENSORS FOR SENSITIVE DETERMINATION OF INFLAMMATION BIOMARKERS IN NON-INVASIVE SAMPLES

E. Sánchez-Tirado*, A. González-Cortés, P. Yáñez-Sedeño, J.M. Pingarrón

Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid

Avda. Complutense s/n 28040 Madrid (Spain) *e-mail: [email protected]

Keywords: electrochemical immunosensor, TGF-β1, IL-1β, TNF-α, AHSG, saliva The analysis of blood biomarkers is fundamental in clinical diagnostic procedures. However, it is increasingly common to use other biological fluids, such as saliva, whose extraction is non-invasive, simple, safe and painless, when compared to the extraction of other types of samples, for example, blood, liquid cerebrospinal fluid or biopsies [1]. One drawback to note is that, usually, levels of biomarkers in saliva are considerably lower than those in other biological samples. Therefore, it is necessary to develop sensitive, simple, low-cost devices with short response times and disposable to carry out their determination. In this work, the construction and analytical performance of several electrochemical platforms for the individual and multiple detection of different inflammation biomarkers, such as transforming growth factor beta 1 (TGF-β1) [3], interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α) [4] and human fetuin A (AHSG), are reported. The determination of these analytes is important for prognosis and diagnosis of different diseases related with inflammation, immunology, atherosclerosis and cancer. The developed methodologies, using novel coupling of bioreceptors, functionalized magnetic carriers, attractive bioassays formats and electrochemical disposable transducers, fully demonstrated the accurate determination of the target analytes at clinically relevant levels in saliva samples.

Figure 1. (a) Viologen-functionalized single-walled carbon nanotubes as carrier nanotags for electrochemical determination of TGF-β1, (b) multiplexed immunosensor for the simultaneous determination of IL-1β and TNF-α, and (c) magnetic multi-walled carbon nanotubes for sensitive determination of AHSG with signal amplification.

References [1] Madera, M.V., Av. Odontoestomatol. 29 (2013) 293–302 [2] Sánchez-Tirado et al., Biosens. Bioelectron. 98 (2017) 240–247 [3] Sánchez-Tirado et al., Anal. Chim. Acta 959 (2017) 66–73

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POLYPYRROLE REACTIONS SENSE ELECTROLYTE CONCENTRATIONS.

Emil Tavárez*, Toribio F. Otero, Samuel Beaumont

Laboratory of Electrochemistry Intelligent Materials and Devices, Technical University of Cartagena, ETSII, Campus Alfonso XIII, 30203, Cartagena, Spain

*e-mail: [email protected] Keywords: conducting polymers, molecular machines, conformational movements, sensing reactions, proprioception. Films of conducting polymers (CPs) have high electronic and ionic conductivity. Used as electrodes in aqueous electrolytes, they exchange ions and water driven by electrochemical reactions for charge and osmotic balance becoming dense and reactive gels. Reversible oxidation/reduction reactions drive reversible conformational movements of every reacting chain, which become a multistep electrochemical molecular machine [1–3]. The cooperative actuation of the molecular machines in the film produces the free volume variation in the film required to lodge or expel counterions and solvent: the film expands and contracts under faradaic control. Our research group has stated a new sensing principle for those reactions involving molecular machines: the energy consumed by the reaction adapts to (senses) any energetic change (chemical, thermal, mechanical…) of the reaction media [4]. Here we will illustrate this principle determining how reversible charge consumed by the polypyrrole oxidation/reduction reactions responds to Na2SO4 concentration variations in aqueous solutions. The reactions were studied by cyclic voltammetry between the same potential limits under constant sweep rate at room temperature. A theoretical description of those reaction-driven chemical sensors is proposed. Rising concentrations (rising chemical energy) shift the reversible electrochemical reactions to deeper oxidation/reduction states with the concomitant increase of: the redox charge, the variation of free volume inside the film and the amount of exchanged counterions and solvent. The process is full reversible. Thus, for conducting polymers (and chemical molecular machines like actin-myosin-ATP in muscles) the available chemical energy controls the extension of the reaction and the reaction energy adapts to and senses the reactant concentration. Those results can indicate how the sensing signal informing brains of the fatigue state of muscles is generated. [1] T. F. Otero, Conducting Polymers: Bioinspired Intelligent Materials and Devices, RSC, 2015. [2] T. Otero, J. Martinez, J. Arias-Pardilla, Electrochimica Acta. 84 (2012) 112–128. [3] T.F. Otero, Conducting Polymers, Electrochemistry, and Biomimicking Processes, in: R.E. White, J.O. Bockris, B.E. Conway (Eds.), Modern Aspects of Electrochemistry, Springer US, New York, 1999: pp. 307–434. http://link.springer.com/chapter/10.1007/0-306-46917-0_3 (accessed January 9, 2013). [4] T.F. Otero, J.G. Martinez, Prog. Polym. Sci. 44 (2015) 62–78. The authors acknowledge financial support from the Seneca Foundation

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ELECTROCHEMICAL IMMUNOSENSORS FOR DETECTING HORMONES RELATED TO OBESITY AND APPETITE REGULATION

G. Martínez-García*, E. Sánchez-Tirado, M.L. Agüí, A. González-Cortés, P. Yáñez-Sedeño,

J.M. Pingarrón

Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid, Ciudad Universitaria s/n, 28040-Madrid, Spain

*e-mail: [email protected] Keywords: Obesity biomarkers, electrochemical Immunosensors Obesity is a pandemic condition that affects around 1900 million people all over the world. It is involved in numerous comorbidities such as hypertension, diabetes and the majority of cardiovascular diseases. Morbid obesity is considered as a chronic inflammatory state which conclude in a dysfunction of endocrine system. Obesity biomarkers are a set of biomolecules that present altered levels in these processes. Among these, the levels of some hormones involved in the complex regulation of the metabolic balance, such as ghrelin, peptide YY and amylin, play an important role in hypothalamus neuronal receptors where satiation or appetite sensation can be produced. In this way, levels of ghrelin (GHRL) peptideare increased before meals to stimulate the appetite, decreasing later. Peptide YY (PYY) is synthesized in the lower intestine and plays an important role in satiety by limiting meal size. Conversely to GHRL, PYY levels are increased after meals. On the other hand, Amylin (AMY), hormone related to adiposity, hunger and satiety,is secreted together with insulin from pancreatic B-cells. Like insulin, plasma amylin levels are low during fasting periods and increase during the meals, being all concentrations directly related to body fat. We have prepared electrochemical competitive immunosensors for the individual and multiple determination of GHRL, PYY and AMY in different human fluids using SPCEs functionalized by grafting or poly(pyrrole propionic acid) electropolymerization (Fig.1).Both modifications provide a high content of carboxyl groups on the electrode surface suitable for direct covalent binding of specific antibodies. Competitive immunoassays strategies involve the use of streptavidin-HRP for amperometric detection of H2O2 mediated by hydroquinone or, streptavidin-AP for the oxidation product of 1-naphtol (1-NP) for monitoring the affinity reaction. The application of these immunosensors, has allowed obtaining good results in real samples.

Figure 1. Electrochemical immunosensors for multiplexed determination of GHRL and PYY (left) and

for AMY determination (right).

CV, 0.0-0.85V vs Agn=20; 100 mV/s

t

i H2O2

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CLICK AND ELECTROCLICK CHEMISTRY AS STRATEGIES FOR THE DEVELOPMENT OF IMMUNOSENSING SCAFFOLS FOR

THE DETERMINATION OF CXCL7 AND IL-1β

S. Guerrero*, L. Agüí, P. Yáñez-Sedeño, J.M. Pingarrón

Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid *[email protected]

Keywords: electrochemical immunosensors, click chemistry, CxCL7, electroclick, IL-1β The proteins IL-β1 and CxCL7 belong to two families of proteins encoded by both genes with outstanding roles in the field of animal cell metabolism, so that a variation of their endogenous levels can be related to alterations of the processes in which they are seen Involved. Thus, CxCL7 belongs to the group of chemokines and is a potent chemoattractant and activator of neutrophils. It has been shown that its activity focuses on the stimulation of various cellular processes, being a potent biomarker of kidneys and pancreas cancer. It is also an antimicrobial protein with bactericidal and antifungal activity. On the other hand, IL-1β protein is a member of the interleukin 1 cytokine family and is an important mediator of the inflammatory response, being involved in a variety of cellular activities, including cell proliferation, differentiation and apoptosis. Nowadays, the application of click chemistry for the preparation of electrochemical immunosensors has been extensively used. This method constitutes a simple and efficient strategy for the covalent immobilization of specific antibodies through an azide–alkyne cycloaddition catalysed by copper (I). In this “click” chemistry azided MWCNTs are assembled to alkyne-functionalized IgGs, obtaining conjugates used as scaffolds for the immunosensor preparation (CxCL7). Following the same design, the first modified platform based on an “electrochemical click” reaction has been developed (IL-1β). IgG-alkyne–azide–MWCNT conjugates are obtained by the application of -400mV (5 min), in the presence of copper sulphate. This mechanism permits us to achieve functionalized surfaces in a shorter period of time. This work describes the preparation of two sandwich-type electrochemical immunosensors, based on screen printed carbon electrodes (SPCEs), modified with both types of click procedures. In both cases, streptavidin labeled with alkaline phosphatase (AP-Strept) were needed for the reduction of 1-naphthyl phosphate (1-NP) to monitor the affinity reaction. All experimental variables were optimized. Good reproducibility has been observed in the preparation of the immunosensor, with a RSD value (n = 5) of 2.8 and 4.5% for CxCL7 and IL-1b, respectively. Likewise, analytically useful signals have been obtained, which in the case of CxCL7 corresponds to an interval of concentration between 0.5 and 500 pg/mL, suitable levels for its application to clinical samples.

Fig.1.- Immunosensor preparation scheme

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EFFECTS OF NON-COMPENSATING IONS ON THE ION-TRANSFER VOLTAMMETRY IN TWO POLARIZABLE INTERFACE SYSTEMS

J.M. Olmos, E. Laborda, A. Molina*

Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence

“Campus Mare Nostrum”, Universidad de Murcia, 30100 Murcia, Spain *[email protected]

Keywords: Analytical equation; Two polarizable interfaces; Ion-transfer voltammetry; Compensating ion The study of the transfer of ionic species across organic barriers between two aqueous solutions has attracted attention from different fields, including the development of electrochemical sensors, the remediation of water and the design of new drugs [1]. In this context, electrochemical methods are very useful, since the distribution of ions can be controlled through the potential difference applied between the two aqueous phases [2]. In this communication, an analytical solution is presented to tackle the study of ion transfer voltammetry in systems of two polarizable interfaces [3]. This equation enables us to obtain the current response in any voltammetric technique, regardless of the concentration, lipophilicity and charge number of the ions that compensate the transfer of the analyte. The theory covers the situation where the compensating ions are not in excess, observing distortions in the voltammograms that can be misunderstood as ohmic drop effects or as slow ion-transfer kinetics. The case where the transfer of the analyte is compensated by several ions is also considered, giving rise to multiple signals that can be mistaken by the transfer of multiple analytes. Finally, the theoretical results are verified with the experimental study of the transfer of the cation tetraethylammonium (TEA+) in water/1,2-dichloroethane/water systems in the presence of several compensating ions of different lipophilicity and concentration [3]. References [1] A. G. Volkov. Liquid Interfaces in Chemical, Biological and Pharmaceutical Applications, CRC Press, 2001. [2] A. Molina, J. González. Pulse Voltammetry in Physical Electrochemistry and Electroanalysis, Monographs in Electrochemistry, Springer International Publishing, 2016. [3] E. Laborda, J. M. Olmos, C. Serna, E. Millán-Barrios, A. Molina. Sensors & Actuators B: Chemical (2018). Submitted Acknowledgements The authors greatly appreciate the financial support provided by the Fundación Séneca de la Región de Murcia (Project 9887GERM/15) and Ministerio de Economía y Competitividad (Projects CTQ-2015-65243-P and CTQ-2015-71955-REDT). J.M.O also thanks the Ministerio de Economía y Competitividad for the grant received under the Project CTQ-2012-36700, co-funded by the European Regional Development Fund.

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STUDY OF ELECTROLYTE CONCENTRATION AND TEMPERATURE VARIATION WITH (PPY/DBS) FILMS FOR ARTIFICIAL MUSCLES

Victor H. Pascual*1, Toribio F. Otero1, Laura Valero2

1Laboratory of Electrochemistry and Intelligent Materials, Universidad Politecnica de Cartagena,

ETSSII, Campus Alfonso XIII,30203, Cartagena, Spain, 2 Engineering School, Universidad Autónoma del Estado de México, Toluca 50000, Mexico

*e-mail: [email protected] Keywords: conducting polymers, electro-chemo-biomimesis, artificial muscles, polypyrrole Scientists and engineers have always dreamt with the idea of creating technological devices able to reach the potential of biological organs. To achieve that goal, that technology should follow the same working principles found in living cells. Conducting polymers are a promising material to accomplish it, since when immersed in a liquid electrolyte and subjected to a reversible oxidation-reduction electrochemical reaction they exchange solvent molecules (water) and ions, as it happens in our own cells. Doing so, they actuate and sense the working conditions simultaneously [1], [2] . An ability reserved until now to biological machines. One of these conducting polymers is the polypyrrole/dodecylbenzene sulfonate (PPy/DBS), about which different works where it exhibits this dual behaviour have been published showing how it is the energy the magnitude that allows to sense the working conditions [3], [4]. In this work, PPy/DBS films were immersed in a LiClO4 aqueous solution with the view to study the sensing properties of two varying magnitudes (temperature and concentration) when the system is subjected to different electrochemical techniques. References [1] T. F. Otero, “Biomimetic Conducting Polymers: Synthesis, Materials, Properties, Functions, and Devices,” Polym. Rev., vol. 53, no. 3, pp. 311–351, Jul. 2013. [2] T. F. Otero and J. G. Martinez, “Biomimetic intracellular matrix (ICM) materials, properties and functions. Full integration of actuators and sensors,” J. Mater. Chem. B, vol. 1, no. 1, pp. 26–38, 2013. [3] L. Valero Conzuelo, J. Arias-Pardilla, J. V. Cauich-Rodriguez, M. Afra Smit, and T. Fernandez Otero, “Sensing and Tactile Artificial Muscles from Reactive Materials,” Sensors, vol. 10, no. 4, pp. 2638–2674, Apr. 2010. [4] X. Wang and E. Smela, “Color and Volume Change in PPy(DBS),” J. Phys. Chem. C, vol. 113, no. 1, pp. 359–368, Jan. 2009. Acknowledgments The research was supported by European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 641822.

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DOXORUBICIN REDUCTION ON MIXED LIPID MONOLAYER COATED AU(111) ELECTRODE BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY.

F. Prieto1, M. Rueda1, N. Naitlho2, M. Vázquez-González1, M.L. González-Rodríguez2, A.M.

Rabasco2 11Department of Physical Chemistry. Faculty of Chemistry and Faculty of Pharmacy. University of

Seville. C/ Profesor García González nº 1, 41012 Seville (Spain), 2Department of Pharmacy and Pharmaceutical Technology. Faculty of Pharmacy. Universidad de Sevilla.

c/ Profesor García González nº 2. 41012 Seville. SPAIN, e-mail: [email protected]

Keywords: lipid monolayers, DMPC, DDAB, cholesterol, Au(111) electrodes, impedance spectroscopy

New drug carriers formed by complex liposomes including anchored gold nanoparticles are receiving increasing attention because of their high transfection efficiency and the absence of cytotoxicity [1,2]. Often, a cationic lipid, didodecyldimethylammonium bromide (DDAB), is included in the liposome composition in order to facilitate the anchoring of the gold nanoparticle [3]. In this work, Langmuir monolayers including DDAB, 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and cholesterol (Ch), have been analysed to decide about the most stable DMPC:Ch:DDAB combination. Monolayers with the optimum composition have been prepared in the electrolyte/ inert gas interface of an electrochemical cell and transferred to Au(111) electrodes for the characterisation by electrochemical impedance spectroscopy. The effects of the inclusion of DDAB into the monolayer composition and the presence of doxorubicin (DOX) in the supporting electrolyte solution are analysed.

In order to avoid the contribution of diffusion to the electrode reduction of DOX, the electrodes were coated in the Langmuir trough with subphases containing the electrolyte and the drug and then were transferred to the electrochemical cells that do not contain the drug. Under these conditions, the reduction of DOX obeys the model for a surface confined electrode reaction. The analysis with the frequency of the impedance data at potentials of the faradaic region provides the charge transfer resistance, Ra, and the adsorption capacitance, Ca, as a function of the potential. The combination of both parameters permits to calculate the rate constant for the reduction in a wide potential range and propose a sequential mechanism with two determining steps: a protonation reaction preceding the first electron transfer and the second electron transfer itself. References [1] A.M. Gobin, E.M. Watkins, E. Quevedo, V.L. Colvin, J.L. West, Small. 6 (2010) 745–752.

doi:10.1002/smll.200901557. [2] J. Conde, A. Ambrosone, V. Sanz, Y. Hernandez, V. Marchesano, F. Tian, H. Child, C.C. Berry,

M.R. Ibarra, P.V. Baptista, C. Tortiglione, J.M. de la Fuente, ACS Nano. 6 (2012) 8316–8324. doi:10.1021/nn3030223.

[3] Y. Jin, S. Wang, L. Tong, L. Du, Colloids Surfaces B Biointerfaces. 126 (2015) 257–264. doi:10.1016/j.colsurfb.2014.12.032.

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BIOMIMETIC SENSOR. POLYPYRROLE REDOX VOLTAMMETRIC CHARGE AND REACTION ENERGY SENSE THE WORKING TEMPERATURE.

Samuel Beaumont*, Toribio F. Otero

Laboratory of Electrochemistry Intelligent Materials and Devices, Technical University of Cartagena,

ETSII, Campus Alfonso XIII, 30203, Cartagena, Spain *e-mail: [email protected]

Keywords: conducting polymers, electrochemical molecular machines, conformational movements, sensing reaction, haptic muscles.

Muscles are natural motors constituted by molecular machines (actin-myosin macromolecules) driven by chemical reactions (ATP hydrolysis). In addition, muscles sense by themselves the chemical and physical working conditions while actuating: they are haptic muscles. The environmental temperature has a strong influence on the muscular reactions of any cold-blooded animal (ectotherm). The underlying working mechanism and the origin of the nervous signal informing the brain about the muscle temperature originating the brain thermal awareness, remains as a controversial subject. In order to study and quantify the temperature influence on both, the muscle reactions and the generation of the sensing signal sent to the brain, we can use any artificial reaction driving molecular motors that can replicate the muscle working principles. Here we will use the reversible electrochemical reactions of films of conducting polymers (CPs) to replicate both, content and functional reactions in functional cells. When films of CPs are used as electrodes in aqueous electrolytes they exchange, under electrochemical reactions, ions and water with the electrolyte for charge and osmotic balance becoming dense and reactive gels. The reversible oxidation/reduction reactions drive conformational movements of every reacting chain, which becomes a multistep molecular electrochemical machine. The cooperative actuation of the molecular motors constituting the film generates or destroys the free volume required to lodge or expel counterions and solvent: the film expands and contracts under reaction control. The film behaves as a dense and reactive gel which composition (molecular machines, ions and water) replicates the intracellular matrix of the sarcomere in natural muscles. The energy consumed by reaction of the molecular machines, or any of its components (consumed charge or potential evolution) responds to (senses) any energetic perturbation (thermal, chemical, mechanical,..) of the reaction media. The reaction drives, simultaneously, the reversible variation of two film functions: actuation through the film volume variation and sensing of the reaction conditions through the consumed energy, consumed charge or potential evolution. Here we present how the voltammetric charge and the energy consumed by the polypyrrole reversible oxidation/reduction in 0.1 M NaCl aqueous solutions respond to and sense the reaction temperature. A theoretical description of the reaction-driven temperature sensors is proposed. By similarity the actin-myosin-ATP reaction energy is proposed as origin of the nervous pulse informing the brain about the thermal working conditions in haptic muscles in general and in coldblooded beings particularly.

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DIRECT ELECTROCHEMISTRY OF HUMAN CYTOCHROME C1

J. L. Olloqui-Sariego*1, A. Guerra-Castellano2, I. Márquez1, M. A. De la Rosa2, J. J. Calvente1, A. Díaz-Quintana2, I. Díaz-Moreno2, R. Andreu1

1Departamento de Química Física, Universidad de Sevilla, c/Profesor García González, 1, 41012

Sevilla, Spain. 2Instituto de Investigaciones Químicas, cicCartuja, Universidad de Sevilla, Consejo Superior de

Investigaciones Científicas (CSIC), 41092 Sevilla, Spain. *e-mail: [email protected]

Keywords: Direct Electron Transfer, Human Cytochrome c1, Protein-Thiol SAMs Interaction

Human Cytochrome c1 (h-Cc1) is the subunit of mitochondrial complex III (cytochrome bc1) responsible for electron transfer to cytochrome c, and to complex IV (cytochrome c oxidase). Numerous studies [1] suggest that intermembrane space conditions, including crowding effects, local electric fields, and protein-protein and protein-lipid interactions affect the functional aspects of membrane proteins, such as h-Cc1.

Possibly due to the difficulties associated with its isolation and purification, the electrochemistry of h-Cc1 is largely unknown. In this work we have explored the influence of the surface interacting with h-Cc1 on its electron transfer properties. For this purpose, we have studied the direct electrochemistry of h-Cc1 adsorbed onto gold electrodes modified with hydrophilic alcohol- and carboxylic acid-terminated self-assembled monolayers (SAMs), at pH 7 and 25 oC.

It is shown that h-Cc1 adsorbed on alcohol-terminated SAMs displays a redox potential (E0 =225mV vs. NHE) close to its value in solution, while a significant negative shift is observed when h-Cc1 is adsorbed onto carboxylic acid-terminated SAMs (E0 = 115mV vs. NHE). Simultaneously, the electron transfer rate constant increases by a factor of ∼70 (from 35 s-1 to 2300 s-1) upon replacing mercapto-1-hexanol by 6-mercaptohexanoic acid as electrode modifier. It is noteworthy also that the electron transfer rate constant obtained for h-Cc1 adsorbed onto 6-mercaptohexanoic acid SAMs is more than twice the reported value for its smaller physiological partner cytochrome c, under the same experimental conditions. Therefore, our results point to an unusual sensitivity of h-Cc1 towards the presence of external carboxylic groups, a characteristic that may help to tune its reactivity in a predetermined way.

References [1] D. Alvarez-Paggi, L. Hannibal, M. A. Castro, S. Oviedo-Rouco, V. Demicheli, V. Tórtora, F. Tomasina, Rafael Radi, D. H. Murgida, Chem. Rev. 117 (2017) 13382−13460. Acknowledgments J. L. O., I. M., J. J. C. and R. A. acknowledge financial support from the MINECO and the European Union FEDER (grants CTQ2014-52641-P and CTQ2015-71955-REDT (ELECTROBIONET)). A. G. C., M. A. R., A. D. Q and I. D. M. acknowledge financial support from MINECO (grant BFU2015-71017-P) and Fundación Ramón Areces.


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DEVELOPMENT OF AN IMMUNOSENSOR FOR SENSITIVE DETERMINATION OF HUMAN ENDOGLIN

E. Martínez-Periñán*, E. Sánchez-Tirado, A. González-Cortés, S. Campuzano, P. Yáñez-

Sedeño, J.M. Pingarrón.

Department of Analytical Chemistry, Faculty of Chemistry, University Complutense of Madrid Avda. Complutense s/n 28040 Madrid (Spain)

*e-mail: [email protected] Keywords: Endoglin, CD105, prostate cancer, screen printed electrodes, biomarker. Human endoglin (CD105) is a 180 kDa homodimeric hypoxia-inducible transmembrane glycoprotein that behaves as an auxiliary receptor for the transforming growth factor-β family of cytokines and plays an important role in hematopoiesis, cardio-vascular development, vascular remodeling and angiogenesis [1]. It has been demonstrated in numerous studies that endoglin levels in different biological fluid are related with the development and progression of various types of cancer as prostate cancer [2] and other important disease such as rheumatoid arthritis [3]. In this way, the development of new fast and cheap analytical methodologies for endoglin determination in biological fluids is of great importance, constituting a powerful diagnostic tool for the aforementioned diseases. In this work we present the development of a new electrochemical inmunosensor for endoglin determination using a sandwich type configuration. Screen printed carbon electrodes were modified, at a first instance, by electropolymerization of pyrrole propionic acid monomer (pPPA). After that the electrode surface was activated with a mixed of EDC/NHSS in order to link the carboxylic groups over the electrode surface with amino groups from mouse anti-human endoglin capture antibody. Subsequently the surface was blocked with casein 1%. Then the electrode was exposed to the analyte (endoglin) followed by the establishment of a sandwich immunoassay using a biotinylated antibody and poly-HRP-streptavidin conjugates for signal amplification. Amperometric measurements were performed by adding 5 µL of 50 mM H2O2 solution onto the electrode. The reduction current from the enzymatically oxidized HQ was monitored at -0.20 V.

References [1] Journal of Pharmaceutical and Biomedical Analysis 129 (2016) 288–293 [2] International Journal of Cancer 124 (2009) 664–669. [3] Annals of the Rheumatic Diseases 59 (Suppl. I) (2000) i65–i71.

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INJECTABLE LI-ION BATERIES

Edgar Ventosa*, María Jesús Escudero, Daniel Pérez, Jesús Palma

Electrochemical Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935 Móstoles, Spain

*e-mail: [email protected] Keywords: Li-ion batteries, semi-solid electrodes, high areal energy density Li-ion batteries (LIBs) are the power source of choice for portable electronics and they are called to play a major role in electromobility. Although LIBs were initially considered as an “expensive” energy storage system for stationary energy storage, the increase in cycle life together with the decrease in cost production has enabled LIBs to become a competitive alternative in this field. Further decrease in costs will not only come from new and cheap active materials, but also from novel approaches to decrease the content of “inactive materials” as well as lowering the manufacturing cost. Semi-solid electrodes containing a suspension of Li-ion or Na-ion intercalation materials and conductive additive were initially proposed for their use in redox flow batteries.1,2,3 In this presentation, we will discuss the possibility of extending the use of semi-solid electrodes to build “injectable” batteries (Figure 1). After introducing the basic idea of an injectable battery, cost analysis of classic LIBs and injectable batteries will be briefly compared revealing the importance of the areal charge capacity (mAh cm-2) in the battery cost. Demonstrations of aqueous injectable batteries using two type of Li intercalation cathode materials will be shown: Zn / LiFePO4 and Zn / LiMn2O4. Although cycliability was limited (ca. 50 cycles) due to side reactions at the Zn electrode, areal charge capacity exceeding 6 mAh cm-2 were demonstrated for these injectable batteries, which is well above the value of 1-3 mAh cm-2 for LIBs. Finally, the remaining challenges of this technology will be summarized. References [1] M. Duduta, B.Y. Ho, V.C. Wood, P. Limthongkul, V.E. Brunini, W.C. Carter, Y.-M. Chiang, Adv. Energy Mater. 2011, 1, 511 [2] E. Ventosa, G. Zampardi, C. Flox, F. La Mantia, W. Schuhmann, J.R. Morante, Chem. Commun. 2015, 51, 14973 [3] E. Ventosa, D. Buchholz, S. Klink, C. Flox, L.G. Chagas, C. Vaalma, W. Schuhmann, S. Passerini, J.R. Morante, Chem. Commun. 2015, 51, 7298 Financial support from Comunidad de Madrid in the framework of the talent attraction programme (2017-T1/AMB-5190) is gratefully acknowledged.

Figure 1. Schematic representation of an

injectable battery

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APPLICATION OF DEMS FOR THE STUDY OF HYDROGEN EVOLUTION REACTION MECHANISM AT NOVEL NANOMATERIALS

E. Pastor*, S. Díaz-Coello, G. García, J.L. Rodríguez, M.C. Arévalo

Departamento de Química, Instituto de Materiales y Nanotecnología, Universidad de La Laguna,

Apartado 456, 38200, La Laguna, Tenerife, Spain *e-mail: [email protected]

Keywords: DEMS, HER, metal carbides, graphene materials Rational design of low-cost and earth-abundant nanomaterials with high efficiency and durability towards the hydrogen evolution reaction (HER) is mandatory for making electrolyzer technology more affordable [1]. The improvement of cathodic catalysts in these devices has been ascribed to different factors, such as their surface area, the composition of the alloy, changes in the metal–metal interatomic distance and the electronic configuration of the material [2]. In this context, recently we reported the synthesis and physicochemical characterization of α-Mo2C and W2C with elevated catalytic activity and stability during the HER in sulphuric and phosphoric acid media [3]. Comparison with glassy carbon (GC) and al Pt supported materials has shown that, as expected, Pt/C catalyst develops the lowest onset potential for the HER, but the activity increases in the following way: GC << W2C < α-Mo2C < Pt/C. Further investigations were carried out with commercial and synthesized transition metal carbides (TMC), ionic liquids (IL), heteroatom-doped graphene materials and nickel supported on graphene-based materials in alkaline and acidic media. The electrochemical reduction of water was investigated using the rotating disk electrode, cyclic and linear sweep voltammetry, chronoamperometry and chronopotentiometry. The elucidation of the HER reaction mechanism at these materials results difficult as calculated Tafel slopes cannot be explained on the bases of the already known Volver, Heyrovsky or Tafel reactions. In the present work, on-line differential electrochemical mass spectrometry (DEMS) was applied to solve this problem. References (if applicable) [1] J.A. Turner, Science 305 (2004) 972–974. [2] M.T.M Koper, J. Solid State Electrochem. 20 (2016) 895–899. [3] G. García, M. Roca-Ayats, O. Guillén-Villafuerte, J.L. Rodríguez, M.C. Arévalo, E. Pastor, J. Electroanal. Chem. 793 (2017) 235–241. Acknowledgments This work has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under project ENE2014-52158-C2-2R (co-funded by FEDER). GG acknowledges the Viera y Clavijo program (ACIISI & ULL) for financial support.


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-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2

-1.0

-0.5

0.0

0.5

1.0 pH = 1.1 pH = 2.1 pH = 3.0 pH = 4.0 pH = 5.6

j |j lim

|-1

E vs. SHE / V

0.36 V

A)

0.0 0.2 0.4 0.6 0.8 1.0 1.2

-1.0

-0.5

0.0

0.5

1.0

j |j lim

|-1

Pt(111) Pt(15 15 14) Pt(10 10 9) Pt(776) Pt(775) Pt(553) Pt(221)

E vs. RHE / V

B)

INFLUENCE OF THE INTERFACIAL CHARGE ON THE HYDROGEN PEROXIDE REDUCTION REACTION ON PLATINUM SINGLE CRYSTAL ELECTRODES

V. Briega-Martos*, E. Herrero, J. M. Feliu

Instituto de Electroquímica, Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain

*e-mail: [email protected] Keywords: hydrogen peroxide reduction, oxygen reduction reaction, interfacial charge The study of the hydrogen peroxide reduction is strategically important in electrocatalysis since H2O2 is one of the possible intermediates in the oxygen reduction reaction (ORR) mechanism. The current inhibition observed below 0.3 V vs. RHE for the ORR on Pt(111) was traditionally attributed to hydrogen adsorption which would prevent the scission of the O-O bond and hence hydrogen peroxide would be formed instead of water [1]. The direct study of the hydrogen peroxide reduction could provide more information about this situation. In this work, H2O2 reduction has been studied in acidic and neutral solutions on different Pt single crystal electrodes. Interestingly, current inhibition occurs at 0.36 V vs. SHE on Pt(111) for all the studied pH values (Fig. 1A) [2]. This potential coincides approximately with the potential of maximum entropy as measured by laser heating experiments [3]. Therefore, the deactivation is not due to hydrogen adsorption, and it is likely to be related to interface water reorganization and the pzfc of the surface. Systematic studies for Pt stepped surfaces also suggest an influence of the local pzc for terraces and steps on this reaction (Fig. 1B) Figure 1: Normalized polarization curves for the HPRR and HPOR on Pt(111) in 1.7 mM H2O2 with pH < 5.4 prepared with NaF/HClO4 mixtures (A) and on different Pt stepped surfaces in 1.7 mM H2O2 and 0.1 M HClO4 (B). Scan rate: 50 mV s-1; rotation rate: 2500 rpm. References [1] N. M. Marković, H. A. Gasteiger, P. N. Ross. J. Phys. Chem. 99 (1995) 3411-3415 [2] V. Briega-Martos, E. Herrero, J. M. Feliu. Electrochem. Commun. 85 (2017) 32-35 [3] R. Martínez-Hincapié, et al. Electrochem. Commun. 58 (2015) 62-64

Acknowledgments This work has been financially supported by the MCINN-FEDER (Spain) through project CTQ2016-76221-P. VBM thankfully acknowledges to MINECO the award of a pre-doctoral grant (BES-2014-068176, project CTQ2013-44803-P).

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STUDY OF ELECTRODE-GEL POYMER ELECTROLYTE INTERFASE IN ZN-BASED BATTERIES

F. Santos1, J. P. Tafur1,2, J. Abad1, A. Urbina3, R. Cid4, J. Rubio-Zuazo4, G.R. Castro4, A.J.

Fernández Romero*1

1Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, U. Politécnica de

Cartagena, Aulario II, Campus de Alfonso XIII, 30203 Cartagena, Spain 2Escuela de Ciencias Químicas e Ingeniería. Universidad Yachay Tech. Ecuador

3Departamento de Electrónica,Universidad Politécnica de Cartagena, Plaza del Hospital 1, 30202, Cartagena, Spain

4,5SpLine CRG BM25 Beamline, European Synchrotron Radiation Facility, 71, Avenue des Martys, 38000, Grenoble, France. Instituto de Ciencia de Materiales de Madrid, Consejo Superior de

Investigaciones Científicas (ICMM-CSIC) 28049, Madrid, Spain *e-mail: ([email protected])

Keywords: Baterías de Zn, GPEs, PVA.

Gel polymer electrolytes (GPEs) are materials which possess both cohesive properties of solids and the diffusive character of liquids. Hence, these electrolytes may be used as excellent substitutes of the liquid electrolytes in batteries. Several types of GPEs can be prepared by trapping liquid electrolytes or ionic liquids into different polymer hosts [1]. At the negative electrode of Zn-based aqueous alkaline batteries, it is broadly accepted that the Zn is oxidized to Zn2+ forming zincate ions (Zn(OH)42–) until the alkaline solution is saturated and zincates are deposited as a poorly conductive ZnO film. However, there are few articles studying the mechanism of the Zn oxidation provided in batteries using GPEs [2]. In this communication, we will present the results obtained by different in situ and ex situ techniques to study the Electrode-GPE interface when a Polyvinyl Alcohol GPE (PVA) is used and then will be compared with those got from Ionic Liquid-based GPEs.

References [1] J.P. Tafur, A.J. Fernández Romero, J. Memb. Sci. 469 (2014) 499. (10.1016/j.memsci.2014.07.007). [2] J. Abad, F. Santos, J.P. Tafur, A. Urbina, E. Román, J.F. González-Martínez, J. Rubio-Zuazo, G.R. Castro, A.J. Fernández Romero, J. Power Sources 363 (2017) 199. (10.1016/j.jpowsour.2017.07.082) Acknowledgments Ministerio de Economía y Competitividad and AEI/FEDER/UE (Refs. ENE2016-79282-C5-5-R). Synchrotron radiation facilities at ESRF BM25B line.


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EXPERIMENTAL OPTIMIZATION OF ALKALINE DIRECT ETHANOL FUEL CELL

R. Escudero-Cid*1, C. Martínez1, D. Herranz1, E. Fatás1, P. Ocón1

1Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, España *e-mail: [email protected]

Polymer electrolyte membrane fuel cells (PEMFC) are devices that are attracting great interest in recent decades due to their high-power densities that are able to reach at low temperatures. Hydrogen and methanol have been the most common fuels used in these devices. However, both have certain drawbacks, such as the problems of production, storage and distribution of hydrogen or the toxicity of methanol [1]. An alternative to these fuels is the use of ethanol, cheaper and less toxic than methanol. The oxidation of ethanol has been the topic of numerous research papers in recent years [2]. It is mainly due to the high energy density and thermodynamic efficiency of this fuel, in addition to the fact that ethanol is considered a green chemical. It can be produced in large quantities as a renewable biofuel from the fermentation of biomass and, in addition, both ethanol and its final oxidation products (CO2 and water) are relatively non-toxic. Direct ethanol fuel cells (DEFCs) meet some requirements for a sustainable energy conversion technology, such as high electrical efficiency, easy handling of ethanol, or low operation temperature, and they are attractive power sources for portable electronic devices [3]. However, the main issue of the improvement of the performance of these fuel cells was the limited development of the anion exchange polymeric membranes (AEMs) as well as the lack of knowledge that exists about the processes that take place in the fuel cell. In the present research, we report the experimental optimization process to improve the final result of polarization and power density curves of DEFCs in alkaline media. Nowadays, there are not many groups working with that kind of systems and it is interesting to study the importance of different changes for the final performance of the fuel cell. Different variables as flowrate, temperature, backpressure or ethanol and KOH concentration were analysed trying to obtain the best performance of the device. One of the main drawbacks of this type of device, and that has been studied in this way, is the significant current drop that appears at high currents due to diffusional problems. References [1] J. R. Varcoe, P. Atanassov, et al., Energy Environ. Sci., 7, 3135–3191, 2014. [2] Y. Wang, K. S. Chen, et al., Appl. Energy, 88, 981–1007, 2011. [3] S. Carrión-Satorre, M. Montiel, et al., Int. J. Hydrogen Energy, 41, 8954-8962, 2015. Acknowledgments This work has been partially supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) under project ENE2016-77055-C3-1-R, by the Madrid Regional Research Council (CAM) under project S2013/MAE-2882 (RESTOENE-2) and by MINECO under project CTQ2015-68844-REDT.

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CHROMIUM (III) OXIDE AS CATALYST IN AIR ELECTRODES TO BE APPLIED IN ZINC-AIR BATTERIES.

F. Santos1, P. Almodóvar2, C. Díaz-Guerra2, A.J. Fernández Romero*1

1Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, U. Politécnica de

Cartagena, Aulario II, Campus de Alfonso XIII, 30203 Cartagena, Spain 2 Dpto. Física de Materiales, Facultad de Ciencias Físicas. U. Complutense de Madrid. Madrid, Spain

*e-mail: ([email protected]) Keywords: chromium (III) oxide, graphene, ORR, Zinc-air battery. Traditionally Pt-based catalysts are considered as one of the most efficient for the ORR. These catalysts are used extensively in fuel cell but its high cost and low availability makes the study of catalysts without Pt a paramount. Among others, transition metals are the most studied elements to replace Pt as active material in the ORR. In this communication the use of chromium (III) oxide on different carbonaceous substrates as positive electrodes in zinc-air batteries will be addressed. Discharge results using chromium (III) oxide nanoparticles as well as chromium (III) oxide onto graphite, graphene, and graphene oxide will be analysed (Figure). In addition to the former, spectroscopic and electrochemical characterization of these electrodes will be shown and commented.

0 20 40 60 80 100 120 140 160 180 200 2200,4

0,6

0,8

1,0

1,2

1,4

Carbon black MnO2 25%+Cr203 1% MnO2 25%+Cr203 9% E4B Electric Fuel LTD. ( Catodo Comercial)

Ewe/V

Capacity mAh/g(GPE)

Figure 1. Discharge curves of Zn-air batteries using different Cr2O3-based cathodes.

References [1] Changlan W., Xueping G., Taizhong H., Xiaoying W., Luping X., Jiemei Y., Haitao Z., Zhaoliang Z., Jitian H., Hao R. International Journal of Hydrogen Energy, 41, 26, 2016, 11099-11107. Acknowledgments Ministerio de Economía y Competitividad y AEI/FEDER/UE (Refs. ENE2016-79282-C5-5-R, MAT2015-65274-R).


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ENHANCED ELECTROCATALYTIC ACTIVITY OF PEROVSKITE MATERIALS IN ENERGY CONVERSION BY INTERMEDIATE TEMPERATURE FUEL CELLS

D. Clematis*1, M.P. Carpanese1,2, S.Presto2, M. Viviani2, M. Panizza1, A. Barbucci1,2

1Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genoa,

Via all’Opera Pia 15, 16145, Genova, Italy 2CNR-ICMATE, c/o DICCA UNIGE Via all’Opera Pia 15, 16145, Genoa, Italy


Keywords: SOFC cathode; oxygen reduction reaction; performance; electrode kinetic An extremely active material for intermediate temperature-solid oxide fuel cells (IT-SOFCs) was obtained by mixing La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) - Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) powders. Different volume ratios were considered: BSCF 50% - LSCF 50% (BL50), BSCF 70% - LSCF 30% (BL70) and BSCF 30% - LSCF 70% (BL30). Electrodes were evaluated by electrochemical impedance spectroscopy (EIS) in a temperature range of 500-650 °C and cathodic overpotential between 0-300 mV. An extraordinary activity for oxygen reduction reaction was extrapolated especially for BL70 samples with a polarisation resistance of 0.021 Ω cm2 at 650 °C, one of the lowest value reported in literature, lower than pure BSCF value obtained by Shao [1]. Also, BL50 and BL30 showed acceptable RP values of 0.027 Ω cm2 and 0.044 Ω cm2, respectively. As reported in Fig.1a for BL70, the kinetic mechanism interpretation it is a challenge due to the strongly effect of operating conditions; especially temperature produced a strong change in impedance spectra shape. With the aim to build a reliable analysis, a possible integration between distribution of relaxation time (DRT) and equivalent circuit (EC analysis) was probed. DRT identified a transition in kinetic mechanism from 500 °C to 650 °C (Fig. 1b). At low temperature electrode was dominated by a Gerischer behaviour, which couples oxygen surface exchange and bulk diffusion [2]. At 650 °C main DRT-peak shifted at higher frequency indicating a process mainly controlled by capacitive phenomena. Further information and more details about the electrode kinetic was provide by EC analysis.

Fig. 1 (a) EIS spectra for BL70 at different temperature (b) corresponding DRT spectra References [1] Z.H. Shao, Nature 431 (2004) 170 [2] L. Almar, J. Szász, A. Weber, E. Ivers-Tiffée, J. Electrochem. Soc. 164 (2017) F289.

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THE EFFECT OF THE ELECTRIC FIELD ON POTENTIOMETRIC SCANNING ELECTROCHEMICAL MICROSCOPY IMAGING

R.M. Souto*1,2, D. Filotás3, G. Nagy3

1Department of Chemistry, Universidad de La Laguna, La Laguna (Tenerife), Spain

2Institute of Materials Science and Nanotechnology, La Laguna (Tenerife), Spain 3Department of General and Physical Chemistry, University of Pecs, Pecs, Hungary


Keywords: scanning electrochemical microscopy, potentiometry, ion-selective microelectrode, galvanic corrosion, electric field Potentiometric SECM –sometimes referred to as Scanning Ion Selective Electrode Technique (SIET)– has become popular among corrosion scientists. The most frequent application is the visualization of galvanic corrosion processes [1,2]. The spatial separation of the anodic and the cathodic sites makes the complex corrosion processes more easily interpretable, and due to the enhanced corrosion rates, conveniently shorter exposure times may suffice to obtain spatially-resolved images of the concentration distributions developed in the solution adjacent to the corroding sample. Despite these beneficial circumstances, quantitative evaluation of galvanic corrosion using potentiometric SECM sometimes produces unexpected results. Izquierdo et al. [2] observed discrepancies between the Z-approach curves recorded over the cathode of an Mg-Fe galvanic couple using either amperometric O2 detection or potentiometric pH measurement. Next, local alkalization could be detected even at 2 mm tip-substrate distance, although the oxygen concentration had already reached bulk values at ca. 900 µm height. In another work, the Mg2+ concentrations monitored using an Mg-ISME above the magnesium disc galvanically-coupled to iron, highly exceeded the upper limit of detection of the probe [3]. In addition, pMg values below the lower limit of detection of the Mg-ISME were observed above cathodically polarized magnesium strips [4]. The explanation for those discrepancies can be given in terms of the formation of an electric field due to the potential difference between the surfaces of the galvanic couple, which has a direct effect on the potential of the sensing microelectrode. Indeed, the potential difference caused by the electric field can be substantially large, exceeding that of the potential difference associated with the activity of the primary ion. In this contribution, we provide experimental evidence of this feature, and investigate the extent to which it influences the final chemically-resolved image. References: [1] A.G. Marques, M. Taryba, A.S. Panão, S. Lamaka, A.M. Simões, Corros. Sci. 104 (2016) 123. [2] J. Izquierdo, L. Nagy, I. Bitter, R.M. Souto, G. Nagy, Electrochim. Acta 87 (2013) 283. [3] J. Izquierdo, A. Kiss, J.J. Santana, L. Nagy, I. Bitter, H.S. Isaacs, G. Nagy, R.M. Souto, J. Electrochem.

Soc. 160 (2013) 451. [4] J. Izquierdo, B.M. Fernandez-Perez, D. Filotas, Z. Öri, A. Kiss, R.T. Mart ın-Gomez, L. Nagy, G.

Nagy, R.M. Souto, Electroanalysis 28 (2016) 1.

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EFFECT OF RESIDUAL ELEMENTS IN LEAD-ACID BATTERIES

A.F. Romero*1, M. Blecua1, J. Valenciano2, F. de la Fuente2, E. Fatás1, P. Ocón1

1Universidad Autónoma de Madrid, Departamento de Química Física Aplicada, C/Francisco Tomás y Valiente 7, 28049, Madrid, Spain.

2Exide Technologies, R&D Centre, 19200 Azuqueca de Henares, Spain. [email protected]

Keywords: Lead Acid Batteries, hydrogen, oxygen and residual elements. Lead Acid Batteries (LABs) have a modern technology in constantly enhancement. One of the points to solve are the problems occur during the performance of the battery reducing the cycle life of LABs. In the charge process at high rate charge the mass transport overpotential increase because the primary (reduction and oxidation of lead (II) sulfate at positive and negative plates respectively) and secondary reactions (evolution of oxygen and hydrogen at positive and negative plates respectively) are developed and the consequences is in connection to the reducing cycle of life of LABs. Lead material used in LABs contains known residual elements1. These elements have a direct relationship with the problem mentioned previously, because there are some previous theories explain that these residual elements can act like catalyst of the evolution of oxygen and hydrogen, therefore, is necessary to study the critical level of each residual element and to identify who is both the catalyst of hydrogen or oxygen. Our objective is to know the critical levels of the different elements, such as nickel (Ni (II)), zinc (Zn (II))….etc. We study the critical element levels in the cell electrolyte, using pure lead material as working electrode. Lead rotating disk electrode in combination with cyclic voltammetry was carried out. Reference electrode was Hg/HgSO4 and big lead as auxiliary electrode. The electrolyte used is H2SO4 of specific gravity 1.28, because this acid concentration was used in market of LABs. He onset potential, Tafel parameters and current density exchange were evaluated. Lead-acid battery cells with capacity aprox. to 1.0 A, will be evaluates with the critical levels of residual elements found in the preceding evaluation, in this case the elements will be again incorporated in the electrolyte. The electric evaluation: Capacity, Cold Cranking Amper (CCA), Initial Charge Accept (ICA) and Cycles with 17.5% Depth of Discharge (DOD) will be done. [1] L.T. Lam, H. Ceylan, N.P. Haigh, T. Lwin, D.A.J. Rand, CSIRO Energy Technology. Soc. 195 (2010) 4494–4512. [1] F. Wang, C. Hu, M. Zhou, K. Wang, J. Lian, J. Yan, S. Cheng, K. Jiang (2016) Research progresses of cathodic hydrogen evolution in advanced. Sci. Bull, DOI 10.1007/s11434-016-1023-0.

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BOOSTING PERFORMANCE OF ALUMINIUM-AIR BATTERY BASED ON IMPROVED ANODE AND CATHODE

A. López Cudero*1, F. J. Pérez-Alonso1, M. Pino1, P. Rodríguez1, J. Chacón1

1 Albufera Energy Storage Parque Cientifico de Madrid, Faraday 7, 28049 – Madrid (Spain)

*e-mail: [email protected] Keywords: Aluminium, Metal-air batteries, ORR, non-precious metal catalysts, alloys Energy Storage Systems (ESS) are nowadays one of the hot topics for both researchers and politicians, since new storage systems are needed in order to accomplish with the commitments of the EU for the next years, that include a reduction of emissions (respect to 1990) by 40% by 2030. In order to meet such a great challenge, new technologies are needed, and, among the new EES, batteries are attracting increasing attention. One of those technologies is the family of the Metal-air batteries that has been identified as one of the most promising battery technology competing for a place in the so-called “post-lithium era”. Within Metal-air batteries, the use of Aluminium shows an outstanding position due to its light weight and ability to exchange three electrons during the electrochemical process, what confers it a very high theoretical volumetric capacity, i.e., 8040 mAh cm−3. Moreover, Aluminium is cheap, abundant, non-dangerous and easily handled.

All Metal-air batteries, similarly to fuel cells, are characterized by the use of a cathode where the oxygen reduction reaction (ORR) takes place. Due to the sluggish kinetics of ORR, the direct application in aqueous based Metal-air batteries of efficient cathodes with low overpotential is far from straightforward. This is even more critical for Aluminium-air batteries that use neutral salt-water electrolyte to avoid self-corrosion of Aluminium. In this electrolyte, the very slow kinetics of ORR results in a poor performance of the Al-air battery, hindering its commercial deployment. Thus, the development of ORR catalysts for the cathode and tailored Aluminium alloys for the anode able, to work in neutral aqueous solutions are key features for obtaining commercial Aluminium-air batteries. In this work, we present the development of improved cathode and anode based on ORR non-precious metal catalysts and Aluminium tailored alloys, respectively. Results show that in the case of the cathode, the optimized ORR catalyst developed by Albufera Energy Storage shows an outstanding activity in neutral media reducing the overpotential in 200 mV with respect to the commercial state–of-the-art MnO2 and 100 mV respect to the Pt/C catalysts. In addition, the use of tailored Aluminium alloys instead commercial ones reduces the overpotential at the anode in 300 mV. These remarkable results demonstrate that the commercialization of Aluminium-air batteries based on neutral electrolytes is viable.

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N-DOPED GRAPHENE AEROGELS MODIFIED WITH Ti AND Co AND ITS ACTIVITY TOWARDS OXYGEN REDUCTION AND EVOLUTION REACTIONS.

J. M. Luque-Centeno*1-2, M. V. Martínez-Huerta2, W. Chen3, D. Sebastián1, K. L. Yeung3, M.

J. Lázaro1.

1Instituto de Catálisis y Petroleoquímica (CSIC), Marie Curie 2, 28049 Madrid, Spain. 2Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain.

3Hong Kong University of Science and Technology. Clear Water Bay, Kowloon, Hong Kong. *e-mail: [email protected]

Keywords: Graphene, Aerogel, Fuel Cell, Electrocatalyst. Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are undoubtedly the most important electrochemical reactions associated with energy conversion and storage technologies, such as fuel cells or water electrolyzers. The use of alkaline media devices improves the kinetics of these reactions and increases the stability of the materials, allowing the use of non-precious metals as catalysts. In particular, graphene based nanocomposites doped with N and modified with Co and Ti oxides have demonstrated good activity for ORR and OER, due to the active sites formed by Me-N-C species (Me = Co, Ti) [1]. In order to improve the properties of this materials, like gas diffusion and performance, graphene oxide can be used as precursor for the synthesis of materials as aerogels with high porosity, allowing the creation of active sites for ORR and OER [2]. The aim of this work is the synthesis of nanostructured materials such as graphene-based aerogels doped with nitrogen and their modification with Co and Ti oxides.

Figure 1. Aerogel structure of TiCo/NrGO aerogel determined by SEM.

The investigated materials have been characterised by elemental analysis, X-ray diffraction, TEM, SEM (Figure 1), Raman Spectroscopy and XPS. The catalytic activity for the ORR and OER has been carried out in a three-electrode system, in 0.1M NaOH. Results for catalyst prepared with 40% of metal loading, show good onset potential for oxygen reduction and evolution reactions.

References [1] J.M. Luque-Centeno, M.V. Martínez-Huerta, D. Sebastián, G. Lemes, E. Pastor, M.J. Lázaro, Renewable Energy, 125 (2018) 182-192. [2] R. Liu, Y. Jin, P. Xu, X. Xing, Y. Yang, D. Wu, Journal of colloid and interface science, 464 (2016) 83-88. Acknowledgments Authors acknowledge financial support given by Spanish Ministry of Economy and Competitiveness (MINECO) through Projects ENE2014-52158-C2-1-R and ENE2017-83976-C2-1-R (co-founded by FEDER) and CSIC Program i-LINK (i-LINK1106). J. M. Luque also acknowledges MINECO for his Ph.D. grant.

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IMPORTANCE OF ANODIC REACTION IN REVERSIBLE ALUMINIUM BATTERIES

David Muñoz-Torrero1, Enrique García-Quismondo1, Edgar Ventosa1, Marc Anderson1,2, Jesús Palma1, Rebeca Marcilla1*

1 Electrochemical Processes Unit, IMDEA Energy Institute, Avda. Ramón de la Sagra 3, 28935

Móstoles, Spain *[email protected] 2 Department of Civil and Environmental Engineering, University of Wisconsin- Madison, 53706, WI,

USA Keywords: Rechargeable Al-Batteries, Ionic liquids, Electrodeposition, Aluminium In the last few years, the development of aluminium batteries has been attracting the attention of scientists worldwide. This growing interest is triggered by the high theoretical gravimetric capacity of aluminium (2.98 Ah g−1), comparable with lithium (3.86 Ah g−1), its volumetric capacity (8.04 Ah cm−3) being four times higher than that of lithium (2.05 Ah cm−3), its low cost, high abundance and safety. One of the most important challenges of Al-battery technology is the development of electrolytes with high electrochemical stability that can allow the reversible electrodeposition of aluminium. In this communication, we report on the electrochemical reaction of aluminium in chloroaluminate-based ILs to obtain a better understanding of the anodic reaction of a reversible Al-battery [1]. Not only the electrodeposition of aluminium but also the reversibility of the reaction in BMImCl:AlCl3 (1:2 M ratio) were systematically investigated by using cyclic voltammetry and galvanostatic charge-discharge techniques. The impact of both the chemical nature and geometry of the anode on the reversibility of the reaction and consequently on the battery performance were investigated using different materials (aluminium, stainless steel and carbon) and different geometries.

Figure 1: CV of BMImCl:AlCl3 (1:2 M ratio) on aluminium Substrate. SEM picture of electrodeposited

Al. References [1] D. Muñoz-Torrero, et al., Journal of Power Sources 374 (2018) 77–83 Acknowledgments: The authors acknowledge the financial support given by the Spanish Government (MINECO/FEDER, UE) through the ALIENA project (RTC-2015-4471-3).

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POLYMER ORGANIC FRAMEWORK NON-PRECIOUS METAL FE/N/C CATALYSTS WITH MARKED ACTIVITY FOR ORR IN ALKALINE MEDIA

Á. García*1, T. J. Haynes1, M. Retuerto1, L. Pascual1, J. Torrero1, M.A. Peña1, S. Rojas1

1Instituto de Catálisis y Petroleoquímica CSIC, C/Marie Curie 2, 28049. Madrid. *e-mail: [email protected]

Keywords: ORR, non-precious metal, Fe, N-doped Among the various classes of non-precious metal catalysts for the ORR, those based on Fe/N/M are the most promising ones. These catalysts are based on transition metal atoms (typically Fe) coordinated to several N atoms inserted within a C-C sp2 matrix. However, the actual nature of the active site remains elusive. In addition, the synthesis of these catalysts, and the formation of the Fe/N is not well understood hitherto. We have synthesized a series of Fe/N/C using 1,2-dicyanobenze and iron acetate as starting materials. A first polymerization was carried out using ZnCl2 as catalyst at 400ºC. The resultant solids were ball-milled and treated at 900ºC in NH3/N2 (catalyst 1-HT). Next, the catalyst was washed with H2SO4 and subsequently treated again at 900ºC in NH3/N2 (2-HT). The solids obtained have been characterized by N2-isotherms, ATG, Raman, TEM/STEM, XPS, XAS, and XRD. 1-HT presents Fe, Fe3C, and C. N pyridinic, N graphitic and N oxide species are observed in all catalysts. ORR performance in alkaline media (0.1 M KOH) was measured. Fig. 1a shows the current densities during the ORR for 1-HT and 2-HT, mass activities are shown in Fig. 1b.

Fig. 1: a) Faradaic current and mass activity of 1HT and 2HT in O2 saturated 0.1 M KOH at 1600 rpm

and 5 mVs-1 The mass activity at 0.9 V for 1-HT is almost 3 A/g decreasing to 0.75 A/g for 2-HT. These values are among the highest ones reported in the literature. In conclusion, we report novel non-precious metal catalysts based on Fe-N-C synthetized by a new method of synthesis. The obtained activities obtained in alkaline media are comparable to state-of-the-art catalysts.

Acknowledgment: Projects ENE2016-77055-C3-3-R from Ministerio de Economía, Industria y Competitividad from Spain, and PIE 201480E122 from CSIC are acknowledged.

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EIS AS A TOOL TO STUDY THE GROWTH OF NANOSTRUCTURED IRON FLUORIDES FOR LI-ION BATTERIES

B. Guitián, X. R. Nóvoa, A. Pintos*

University of Vigo, EEI, ENCOMAT Group, Campus Universitario, 36310 Vigo, Spain *e-mail: [email protected]

Keywords: Iron fluoride, Li-ion batteries, electronic conductivity Li-ion batteries represent an important aspect in the field of energy storage. The reaction mechanism in both electrodes, the anode and the cathode; is based in insertion reactions. The cathode material and the electrical contact between active material and the current collector still represents the main limitation of the cell capacity. Direct grown of the active material on the current collector decreases ohmic resistance and increases the available charge. This guarantees good electrical contact and, if the active material is able to work under conversion reactions it is possible to increase the nominal capacitance respect to insertion reactions. The electrode material will reach all its oxidation states. Transition metal fluorides, such as FeF3 are good candidates to the conversion reactions with lithium ions due to their high nominal capacity [1,2]. Direct formation of a fluoride-based layer has been achieve by anodizing iron strips in ethylene glycol and NH4F as electrolyte, resulting in highly nanoporous layers of a mixture of iron oxyhidroxifluorides [3]. Nevertheless, those fluoride-rich layers were of poor electronic conductivity, which limits their performance as electroactive material. So, the present work focuses on the improvement in the electronic conductivity of this layers synthesized as in [3], changing the substrate material or even grafting with some elements after synthesis of the active material. References [1] F. Badway, N. Pereira, F. Cosandey, G.G. Amatucci, Carbon-Metal Fluoride Nanocomposites, J.

Electrochem. Soc. 150 (2003) A1209. doi:10.1149/1.1596162. [2] F. Badway, F. Cosandey, N. Pereira, G.G. Amatucci, Carbon Metal Fluoride Nanocomposites, J.

Electrochem. Soc. 150 (2003) A1318. doi:10.1149/1.1602454. [3] B. Guitián, S. Lascaud, X.R. Nóvoa, L. Ribeaucourt, E. Vidal, On the growth of nanostructured

iron hydroxy-fluorides for Li-ion batteries, J. Power Sources. 241 (2013) 567–571. doi:10.1016/j.jpowsour.2013.04.145.

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2D PD NANOSHEETS AS EFFICIENT ELECTROCATALYSTS FOR ETHANOL OXIDATION. EVIDENCES OF C-C SCISSION AT LOW POTENTIALS

M. Farsadrooh1,2, J. Torrero1, L. Pascual3, M. A. Peña1, M. Retuerto1, Sergio Rojas*1

1Grupo de Energía y Química Sostenible, ICP/CSIC, C/Marie Curie 2, 28049, Madrid. 2Department of Applied Chemistry, University of Sistan and Baluchestan, P.O. Box 98135 674, Zahedan, Iran.

3Instituto de Catálisis y Petroleoquímica, CSIC, C/Marie Curie 2, 28049, Madrid, *e-mail: [email protected]

Keywords: Pd-nanosheets, ethanol electrooxidation, DEFCs, IRRAS Ethanol is a suitable second-generation biofuel that can be used in direct ethanol fuel cells. Partial oxidation products (C2) are usually formed during ethanol electrooxidation (EOR). In fact, the total oxidation of ethanol to CO2 is limited even with state-of-the-art Pt-based catalysts. 2D-Pd nanosheets have been synthesized by a simple chemical approach from Pd(acac)2 in organic solution using CO as reducing agent. Figure 1a shows a representative micrograph for Pd-nanosheets showing a 2D-flat morphology. Figure 1b illustrates the stacking of several Pd-layers exhibiting a large fraction of Pd atoms in steps and edges. XRD reveal the preferential exposure of 111 planes. The electrochemical surface area (ECSA) of Pd-nanosheets has been evaluated from the integration of the charge associated to the reduction of Pd-oxides.

Figure 1. a) and b), representative micrographs for Pd-nanosheets; c) CVs in 0.5 M C2H5OH/0.1 M KOH at 10 mVs-1 (black Pd-nanosheet, red Pd-black); d) IR spectra during EOR 0.5 M C2H5OH/0.1 M KOD at 5 mVs-1. ECSA values of ca. 200 and 60 m2/gPd are obtained for Pd-nanosheets and commercial nanosized Pd-black. As observed in Figure 1c, Pd-nanosheets render higher currents during the EOR than Pd-black. In situ IR studies during the EOR reveal the formation of carbonates (band at ca. 1390 cm-1) at low potentials (30 mV) but the predominance of acetates at potentials higher than 250 mV. These observations indicate that C-C scission of ethanol takes place at low potentials on Pd-nanosheets. Acknowledgment: Projects ENE2016-77055-C3-3-R from Ministerio de Economía, Industria y Competitividad from Spain, and PIE 201480E122 from CSIC are acknowledged.

0 400 800 1200 16000.000

0.025

0.050

0.075

0.100

i / mA

cm-2 Pd

E / mV 1700 1600 1500 1400 1300

1050

16311715

15601416

1450

250

wavenumbers / cm-1

700

13911453 ERDE

R/R0 = 5%

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ELECTROCHEMICAL STUDY OF GRAPHENE-BASED CATHODES FOR FULL CELLS IN LITHIUM-SULFUR BATTERIES.

A. Benítez*1, D. Di Lecce2, G. A. Elia3, A. Caballero1, J. Hassoun2 and J. Morales1

1Dpto. Química Inorgánica e Ingeniería Química, I.U.I. Química Fina y Nanoquímica. Campus de Rabanales – Universidad de Córdoba, 14071 Córdoba, Spain.

2Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara, 17, 44121, Ferrara, Italy.

3Technische Universität Berlin, Research Center of Microperipheric Technologies, Gustav-Meyer-Allee 25, 13355 Berlin, Germany.

*e-mail: [email protected] Keywords: 3D-graphene; solvothermal-microwave; silicon, Li-S battery. Three dimensional graphenes (3DG) have been studied with the aim of examining their properties in lithium batteries [1]. Here, it is proposed the use of graphene to synthetize graphene-sulfur (G-S) composites as a cathode in Li-S batteries. The synthesis of graphene is carried out from graphitic oxide (GO), derivative of graphite. GO is prepared by the modified Hummers’ method, and subsequently, by means of a reduction step, 3DG is obtained using a microwave assisted solvothermal technique with determined conditions of pressure and temperature. Graphene-Sulfur composite (3DG-S) is prepared by a chemical method that uses ethylenediamine to form nano-particles of sulfur, achieving functionalized graphenes with a better electrochemical stability. The strong affinity of sulfur for this graphene allows to develop batteries with good properties of cycling and high energy density. The results show remarkable electrochemical performance, achieving high values of specific capacity and energy.

In this work we report an efficient lithium-ion battery using enhanced sulfur-based cathode and silicon oxide-based anode as novel energy-storage system. Electrochemical tests indicate the 3DG-S electrode as very stable and performing cathode in lithium half-cell, with capacity ranging from 1200 to 1000 mAh gS

−1 at C/10 and 1C rates, respectively. The LiySiOx-C/3DG-S battery reveals very promising results with a capacity of about 450 mAh gS

−1 delivered at average voltage of about 1.5 V over 200 cycles, suggesting the characterized materials as suitable candidates for low-cost and high-energy storage application.

References [1] C. Hernández-Rentero, O. Vargas, A. Caballero, J. Morales, F. Martín. Solvothermal-induced 3D graphene networks: Role played by the structural and textural properties on lithium storage. Electrochim. Acta. 222 (2016) 914–920. Acknowledgments: This work was performed with the financial support of the MINECO (Projects MAT2014-59907 & MAT2017-87541-R) and Junta de Andalucía (Group FQM-175).

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FIRST-PRINCIPLES DESIGN OF MIXED PROTON-ELECTRON CONDUCTORS FOR SOLID-OXIDE FUEL CELL ELECTRODES

Ana B. Muñoz-García*1, Michele Pavone2

1Department of Physics “Ettore Pancini”, 2Department of Chemical Sciences, Università di Napoli

Federico II, Complesso Univ. Monte Sant’Angelo, Via Cintia 21, 80126 Naples Italy. *e-mail: [email protected]

Keywords: solid oxide fuel cells, proton ceramics, mixed proton electron conductor Electrolyzer and fuel cells based on proton-conducting solid oxides (PC-SOEC/FC) are gaining ground in the energy conversion scenario, thanks to fast proton diffusion rates at convenient operating temperatures. However, current performances are curbed by severe limitations of common electrodes [1]. Within this context, here we outline the latest work of our group on the rational design of innovative electrode materials for PC-SOEC/FC applications. With first-principles methods, we aimed at providing unbiased explanations and predictions of materials properties and functions, so to assess new design principles based on quantum mechanics. The desired electrode materials for PC-SOEC/FCs should pair mixed proton/electron conductive (MPEC) features to good catalytic activity. We followed two design strategies: induction of proton conduction to mixed ion-electron conductors to obtain triple conducting oxides [2] or induction of electronic conduction on well-known proton conductor materials [3]. To this end, in bulk solids we evaluated oxygen vacancy formation and water uptake enthalpies, and we characterized the minimum-energy path for proton migration and the corresponding barrier heights. Then, we investigated the catalysis associated to the four proton-coupled electron transfer processes for the oxygen evolution reaction (OER) and reverse oxygen reduction reaction (ORR) at the electrode surfaces. Our calculations revealed the structural and electronic features than are needed for an effective bifunctionality towards the OER and ORR. Our findings can trigger the targeted experimental synthesis and testing of new single- phase electrodes and can enable the deployment of reversible proton-conducting SOEC/FC devices. Moreover, our analysis can be exploited for the rational design of bifunctional electrocatalytic systems with similar key characteristics. References [1] L. Bi, S. Boulfrad, and E. Traversa, Chem. Soc. Rev. 43 (2014) 8255-8270. [2] A. B. Muñoz-García and M. Pavone, Chem. Mater. 28 (2016) 490-500. [3] A. B. Muñoz-García, M. Tuccillo, and M. Pavone, J. Mater. Chem. A 5 (2017) 11825-11833.

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DYE-ELECTRODE INTERFACE IN P-TYPE PHOTO-ELECTROCHEMICAL CELLS: NEW INSIGHTS FROM AB INITIO CALCULATIONS

Michele Pavone*1, Ana B. Muñoz-García2

1Department of Chemical Sciences, 2Department of Physics “Ettore Pancini”, Università di Napoli

Federico II, Complesso Univ. Monte Sant’Angelo, Via Cintia 21, 80126 Naples Italy. *e-mail: [email protected]

Keywords: dye-sensitized solar cells, photoelectrochemical cells, ab initio calculations For the last decades, dye-sensitized solar cell (DSSC) technologies have been challenging solid-state photovoltaics for solar energy conversion into electricity. Remarkably performances have been recently achieved with conventional n-type DSSCs, thanks to great experimental and theoretical efforts devoted to understanding and tuning the n- DSSC materials properties and functions [1]. The research on p-type DSSC, instead, is still in its infancy and, so far, their poor performances have hindered the foreseen development of tandem cells, i.e. solar cells with a photo-anode (from n-DSSC) and a photo-cathode (from p-DSSC). A deeper and more comprehensive understanding of structure-property- function relationships in photocathode device is thus crucial for further advancements. In this contribution, we will discuss our first-principles studies on state-of-the-art photocathodes based of nickel oxide and prototypical dyes (e.g., C343) [2]. We will highlight the p-NiO electrode features, the dye molecular properties and how overall properties are affected by their mutual interactions. We will discuss the design principles for new push-pull dyes [3] and for new electrodes that can substitute NiO for achieving better efficiencies. Our quantum-mechanical analyses of the p-DSSC model will provide new insights on the dye-electrode interface, paving the route to an effective, rational design of new and better performing photocathodes for photovoltaics and photoelectrochemical cells. References [1] A. Hagfeldt, G. Boschloo, L. Sun, L. Kloo, and H. Pettersson, Chem. Rev. 110 (2010) 6595-6663. [2] A.B. Muñoz-García and M. Pavone, Phys. Chem. Chem. Phys. 17 (2015) 12238-12246 [3] J. Massin, S. Lyu, M. Pavone, A.B. Muñoz-García, B. Kauffmann, T. Toupance, M. Chavarot- Kerlidou, V. Artero, and C. Olivier, Dalton Trans. 45 (2016) 12539-12547.

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ELECTRO-FENTON PROCESS AT NEUTRAL pH USING A CARBON-FELT CATHODE

Z.H. Ye, E. Brillas, P.L. Cabot, F. Centellas, I. Sirés*

Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain

*e-mail: [email protected] Keywords: BHA, carbon-felt, electro-Fenton, Fe(III)-EDDS, neutral pH, water treatment In recent decades, electrochemical advanced oxidation processes (EAOPs) have been proven excellent candidates to treat wastewater containing refractory micropollutants. Among them, one of the most popular techniques is the electro-Fenton (EF) process, in which H2O2 and externally added Fe2+ can be simultaneously (re)generated by electrochemical reduction of dissolved oxygen and Fe3+ ions at a cathode with large surface area under acidic conditions [1]. However, several drawbacks still limit the large-scale application of EF: (i) it demands acidic conditions (pH 2.5-3.5) to maintain high performance, and (ii) large amounts of H2O2 are accumulated at the cathode, resulting in a poor electroreduction of Fe(III). In this study, ethylenediamine-N,N'-disuccinic (EDDS) acid, an aminopolycarboxylic acid, was employed to form the Fe(III)-EDDS complex, which is proposed for the first time to modify the conventional EF process based on uncomplexed iron ions. The performance of Fe(III)-EDDS-assisted EF process was evaluated from the degradation of butylated hydroxyanisole (BHA). Up to 95% removal was achieved in 45 min with carbon-felt cathode, whereas only 60% and 55% removal was obtained in conventional EF using carbon-felt and carbon-PTFE air-diffusion cathode with hydrated Fe3+ as catalyst source, respectively. However, with the air-diffusion cathode, only 21% BHA abatement was achieved in the Fe(III)-EDDS-assisted EF system, which can be attributed to the large amount of H2O2 generated on such cathode. The optimization of operation conditions included the study of the effects of current density, pH and Fe(III)-EDDS ratio and dosage. The evolution of the different iron species, H2O2 and Fe(III)-EDDS complex was clarified. Using 0.1 mM Fe(III)-EDDS at 16.67 mA/cm2 and neutral pH, up to 48% Fe(II) regeneration was achieved in 10 min with carbon-felt cathode. Under the optimal conditions, 50% mineralization was achieved at 180 min, despite the contribution of EDDS to the initial total organic carbon (TOC) content. The intermediates generated during the oxidation of BHA were identified by GC-MS. In addition, the degradation mechanism of Fe(III)-EDDS-assisted EF process and a degradation pathway for BHA is finally proposed. References [1] E. Brillas et al, Chem. Rev. 109 (2009) 6570-6631. Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU) and PhD scholarship awarded to Z. Ye (State Scholarship Fund, CSC, China).

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ELECTROCHEMICAL TREATMENTS AND LOW CONDUCTIVITY SOLUTIONS: OVERCOMING SUPPORTING ELECTROLYTE ADDITION.

D. Clematis*1, N. Klidi2, G. Cerisola1, M.P. Carpanese1, M. Delucchi1, A. Barbucci1,

M. Panizza1

1Department of Civil, Chemical and Environmental Engineering (DICCA), University of Genoa,

Via all’Opera Pia 15, 16145, Genova, Italy 2 Unité de Recherche Electrochimie, Matériaux et Environnement UREME, Faculté des Sciences de

Gabès, Université de Gabès, 6072 Gabès, Tunisie *e-mail: [email protected]

Keywords: EAOPs; low conductivity; Solid polymer electrolyte; BDD anode; Electrochemical treatment of solutions with low conductivity is currently an open issue [1]. One of the most used method to get over this problem is the addition of a supporting electrolyte, that can lead to collateral problems. In this study a different approach to treat wastewater with low conductivity was proposed through a new electrochemical cell setup based on solid polymer electrolyte (SPE) [2]. In this system, electrolyte is a Nafion® N324 ion exchange membrane sandwiched between a Nb/BDD mesh anode and a Ti/RuO2 cathode (Fig.1). The process effectiveness was evaluated using crystal violet (CV) as model compound. Influence of several parameters was taken into account, such as applied current, water conductivity, stirring rate and temperature. SPE system, thanks to •OH radicals produced during electrolysis, allowed a complete removal of CV and almost TOC. A particular benefit came from the increase of stirring rate, implying that oxidation was under mass-transport control. The addition of Na2SO4 or NaHCO3 as supporting electrolyte caused a slower CV removal. Energy consumptions (Ec) were calculated under best experimental conditions (I = 1A; stirring rate = 800 rpm; T = 20°C), as a function of CV and TOC removal: for dye removal process the Ec needed was 15 kWh m-3, while a complete mineralization required 60 kWh m-

3, an acceptable value considering the low conductivity of solution. Fig. 1 Open sketch of electrochemical cell.

References [1] P. Ma, H. Ma, S. Sabatino, A. Galia, O. Scialdone, Chem. Engin. Journal 336 (2018) 133–140. [2] D. Clematis, G. Cerisola, M. Panizza, Electrochem. Commun. 75 (2017) 21–24.


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COMBINING ELECTROCOAGULATION WITH ELECTRO-OXIDATION FOR THE REMOVAL OF NON-IONIC ORGANOCHLORINE COMPOUNDS

Alexandra Raschitor*, Javier Llanos, Pablo Cañizares, Manuel A. Rodrigo

Chemical Engineering Department, University of Castilla-La Mancha,

Enrique Costa Novella building. Av. Camilo José Cela nº 12, 13071 Ciudad Real, Spain *[email protected]

Keywords: organochloride pesticides; electrocoagulation; electrooxidation; BDD The use of pesticides has a strong impact on the ecosystems putting in danger not only the aquatic flora and fauna but also the human health. According to their properties, this organoclorine compounds can migrate from the surface of the soil to the groundwater or washed out to the surface water from the vicinity. Depending on their solubility degree, they can be more or less easily dispersed. The present work is focused on the highly efficient removal of non-ionic organochlorine pesticides by integrating concentration steps such as electrocoagulation with electro-oxidation using BDD. The model pollutant selected was oxyflourfen, a large-spectrum organochlorine herbicide used to control certain annual weeds in vegetables, fruit and other crops. Because it has a very low solubility in water, it is usually supplied as granules or an emulsified concentrate. It was previously reported that this pollutant can be successfully concentrated using electrocoagulation with Fe electrodes [1]. The oxyfluorfen micelles are trapped by the electrogenerated Fe hydroxide and then separated from the wastewater by sedimentation. Next, the concentrated sediment is dissolved, and this concentrate treated by electro-oxidation process using a BDD commercial cell. Additionally, several tests were performed adding hydrogen peroxide to the concentrate, in order to take advantage of the iron previously dissolved thus promoting Fenton reaction. Results obtained show that coupling concentration and degradation allows to decrease considerably the overall specific power consumption, compare to single electro-oxidation of the raw wastewater. Moreover, adding hydrogen peroxide clearly improves the rate of the degradation process as it promotes the occurrence of Fenton reaction together with BDD electro-oxidation. References [1] M. Muñoz, J. Llanos, A. Raschitor, P. Cañizares, M.A. Rodrigo, Electrocoagulation as the Key for an Efficient Concentration and Removal of Oxyfluorfen from Liquid Wastes, Industrial and Engineering Chemistry Research 56 (2017) 3091-3097. Acknowledgments The financial support from the Spanish Ministry of Economy, Industry and Competitiveness and European Union through project CTM2016-76197-R (AEI/FEDER, UE) is gratefully acknowledged.

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NO PARTICLE SIZE EFFECTS IN THE ELECTROCHEMICAL CONVERSION OF CO2 TO FORMATE ON SN ELECTRODES

C.M. Sánchez-Sánchez*1, A. Del Castillo2, M. Álvarez-Guerra2, J. Blanchard3, A. Irabien2

1Sorbonne Université, CNRS, Laboratoire Interfaces et Systèmes Electrochimiques, LISE, F-75005 Paris,

France, 2Universidad de Cantabria, Dep. Chemical and Biomolecular Engineering, ETSIIT, Avda. Los Castros s/n, Santander 39005, Spain, 3Sorbonne Université, CNRS, Laboratoire de Réactivité de

Surface, LRS, F-75005 Paris, France *e-mail: [email protected]

Keywords: Electrocatalysis, CO2 reduction, HCOOH Recycling of CO2 emissions by direct electrocatalytic reduction of CO2 has been pointed out as a feasible method for CO2 conversion into useful chemical products and fuels. In particular, formic acid (HCOOH) represents one of the most interesting products obtained, since HCOOH is widely used in different industrial applications, as well as, it has been proposed as a renewable hydrogen carrier and suitable fuel for fuel cells [1]. Among the group of metals with high hydrogen evolution reaction overpotential and high selectivity towards HCOOH production, Sn exhibits the lowest toxicity and represents one of the best options in terms of cost and selectivity [2]. Electroreduction of CO2 on spherical Cu nanoparticles has been recently proved as a surface-sensitive reaction [3], where the product selectivity is drastically affected by the particle size. Nevertheless, no attention has been paid to evaluate the electrochemically active area in Sn supported electrodes, which does not allow the proper evaluation of the particle size effect in the electrocatalytic reduction of CO2 on Sn particles. This is because there is not a specific chemisorption reaction to measure the catalytic surface of Sn electrodes. For this reason, we propose N2 physisorption, which is a non-selective method for Sn, but can be applied to measure non-supported Sn nanoparticles surface area by assuming negligible surface lost after being deposited on the support. This approach for evaluating Sn particles surface area allow us to present experimental evidences of no significant particle size effects in the electrocatalytic reduction of CO2 on Sn nanoparticles, neither in activity nor in reaction selectivity down to 15 nm size. References [1] D. Du, R. Lan, J. Humphreys, S. Tao, J. Appl. Electrochem. 47 (2017) 661. [2] A. Del Castillo, M. Alvarez-Guerra, J. Solla-Gullón, A. Sáez, V. Montiel, A. Irabien, J CO2 Util. 18 (2017) 222. [3] R. Reske, H. Mistry, F. Behafarid, B. R. Cuenya, P. Strasser, J. Am. Chem. Soc. 136 (2014) 6978.

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Unravelling the Metal-Support Interaction in Pt NPs Supported on Sulphur Doped Mesoporous Carbon

C. Durante*, R. Brandiele, M. Zerbetto, V. Perazzolo, G. A. Rizzi, A. Gennaro

Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy *e-mail: ([email protected])

Keywords: Pt NPs, sulphur, mesoporous carbon, ORR, fuel cell Mesoporous carbons (MCs) are highly porous materials, which offer high surface area and a porous network able to improve mass transfer in chemical or electrochemical reactions [1]. In previous papers we demonstrated that Pt NPs on nitrogen or sulphur doped mesoporous carbons are highly active and show high mass activity towards oxygen reduction reaction (ORR) [2]. The aim of this paper is to define whether the sulphur heteroatoms present as thiophenic like group affect the Pt nucleation and growth, and afford a better material, in terms of dimension and dispersion of Pt nanoparticles, and a better electrocatalytic activity towards oxygen reduction. Four mesoporous carbons with the same morphological structure, but different S contents (4%, 6%, 8% and 12%) were prepared and were modified with Platinum nanoparticles (Pt@S-MC) by solid state reduction, by H2 at high temperature. Electrochemical characterization showed that Pt@S-MCs are highly catalytic materials for ORR in terms of both E1/2 and mass activity. A clear correlation between sulfur content and the shift of the half wave potential during ORR catalytic test was observed, i.e. the higher the sulfur content, the higher the catalytic activity (Fig. 1a). On this regard, DFT calculations on three thiophenic groups sited close to each other are indicative of a clear stabilization of Pt nucleus of at least 50 KJ/mol with respect to a perfect graphene layer (Fig. 1b)

Figure 1: a) LSV at RDE of Pt@S-MC catalysts with different sulfur contents, in O2 saturated 0.5 M

H2SO4 electrolyte. b) DFT optimized structure of Pt atom on S-MC. References [1] V. Perazzolo, C. Durante, R. Pilot, A. Paduano, J. Zheng, G.A. Rizzi, A. Martucci, G. Granozzi, A. Gennaro, Carbon, 95 (2015) 949–963. [2] V. Perazzolo, R. Brandiele, C. Durante, M. Zerbetto, V. Causin, G. A. Rizzi, I. Cerri, G. Granozzi, A. Gennaro, ACS Catal. 8 (2018) 1122−1137.

0.2 0.4 0.6 0.8 1.0-6

-4

-2

0 Pt/S-MC Pt/S-MC1 Pt/S-MC2 Pt/S-MC3 Pt/C TKK

j / m

A cm

-2

E / V vs RHE

a b

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PROGRESS IN THE ELECTROCHEMICAL DEGRADATION OF POLY- AND PERFLUORINATED COMPOUNDS

Ane Urtiaga*, Nazely Diban, Alvaro Soriano, Beatriz Gómez-Ruiz

Department of Chemical and Biomolecular Engineering, University of Cantabria, Av. de Los Castros

s/n. 39005 Santander. Spain. *e-mail: [email protected]

Keywords: perfluorinated alkyl substances; PFASs; PFOA; PFOS, electrolysis The high-energy C-F bonds convert poly- and perfluoroalkyl substances (PFASs) into non-biodegradable, highly persistent and bio-accumulative compounds when they contain long alkyl chains. Recently, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been subjected to intense research due to their potential toxicity and the extent of their environmental distribution. However, many of the already published studies emphasize the low efficiency of conventional water treatment technologies for the PFASs elimination. This work is aimed at studying the electrochemical removal of PFASs from direct and secondary emission sources, i.e.: industrial manufacturing of fluorochemical compounds [1], landfill leachates [2] and groundwater impacted using aqueous film-forming foams [3]. Several groups of PFASs are included in the study: perfluoroalkylsulfonic acids, perfluoroalkyl carboxylic acids, n:2 fluorotelomer carboxylic acids, n:2 fluorotelomer sulfonamides. The influences of the following variables on the rate of removal, defluorination and mineralization are analysed: i) type of anode material (microcrystalline BDD, ultrananocrystalline BDD and Ti/RuO2) [4]; ii) background wastewater composition; and iii) electrochemical variables such as the applied current density and the composition of the background electrolyte. Also, the contributions of both direct electron transfer and hydroxyl radical mediated oxidation to the governing electrooxidation pathway are discussed. Acknowledgments Financial support from project CTM2016-75509-R (MINECO, SPAIN-FEDER 2014/20) and Spanish Excellence Network E3TECH is acknowledged References [1] I. Fuertes, S. Gomez-Lavín, M.P. Elizalde, A. Urtiaga. Perfluorinated alkyl substances (PFASs) in northern Spain municipal solid waste landfill leachates. Chemosphere 168, 399-407 (2017). [2] B. Gomez-Ruiz, S. Gómez-Lavín, N. Diban, V. Boiteux, A. Colin, X. Dauchy, A. Urtiaga. Efficient electrochemical degradation of poly- and perfluoroalkyl substances (PFASs) from the effluents of an industrial wastewater treatment plant. Chem. Eng. J. 332, 196-204 (2017) [3] C. Schaefer, C. Andaya; A. Urtiaga; E. R. McKenzie; C. P. Higgins. Electrochemical Treatment of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in Groundwater Impacted by aqueous film forming foams (AFFFs). J. Haz. Mat., 295, 170-175 (2015). [4] B. Gómez-Ruiz, N. Diban, A. Urtiaga. Comparison of microcrystalline and ultrananocrystalline boron doped diamond anodes: Influence on perfluorooctanoic acid electrolysis. Sep.& Purif. Technol. in press (2018), https://doi.org/10.1016/j.seppur.2018.03.044

http://www.sciencedirect.com/science/article/pii/S1385894717305740



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Nitrogen Doped Mesoporous Carbons, Prepared from Templating Propylamine Functionalized Silica, as Interesting Material for Supercapacitors

R. Brandiele*,1 J. Seri2, A. Gennaro1, L. Picelli1, G.A. Rizzi1, F.Soavi2 and C. Durante1,

1 Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy

2Department of Chemistry “Giacomo Ciamician”, University of Bologna, Via Selmi 2, 40126 Bologna, Italy

*e-mail: [email protected] Keywords: nitrogen doped, supercapacitors, hard template, mesoporous carbon Highly accessible surface area and heteroatom-doping are key features of carbon electrode materials to be used in electrochemical supercapacitors (SC) [1]. In this paper, nitrogen doped carbon materials were synthetized according to a hard template method by pyrolysis at 950 °C for 2 h of sucrose and employing propylamine functionalized silica as templating agent (NMC-1) [2]. The resulting materials were compared with mesoporous carbon obtained by pyrolysis of sucrose or 1,10-phenantholine but employing a non-functionalized silica while showing similar texture properties. XPS, elemental analysis and EDX showed the presence of nitrogen groups in NMC-1, confirming the doping action of the functionalized silica. The interest of this investigation is to understand how doping occurs when a functionalized silica is employed, and whether the nitrogen doping remains a surface property or it is extended also to the bulk of the material, influencing the morphological and the electrical properties of the resulting carbon. The comparison of electrochemical behaviours in term of capacitive response were also evaluated considering the different synthetic approaches. The materials were fully characterized by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy in 3-electrode cells and in SC configuration with different electrolytes, aqueous and organic including ionic liquids. The results demonstrate that this new class of carbonaceous materials is of great interest for supercapacitor applications.

Figure 1. Hard template approach employing propylamine functionalized silica and sucrose. [1] C. Zhong, Y. Deng, W. Hu, J. Qiao, L. Zhang, J. Zhang, Chem. Soc. Rev., 2014, 44, 7484–7539. [2] R. Brandiele, L. Picelli, R. Pilot, V. Causin, A. Martucci, G.A. Rizzi, A.A. Isse, C. Durante, A. Gennaro Chemselect, 2017, 2, 7082–7090.

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TOWARDS ELECTRO-OXIDATION PROCESSES SUPPLIED BY RENEWABLE ENERGIES

M. Millán1, M.A. Rodrigo1, C.M. Fernández-Marchante1, P. Cañizres1, J. Lobato1*

1Chemical Engineering Department, University of Castilla-La Mancha, Enrique Costa Novella Building, Av. Camilo José Cela nº 12, Ciudad Real (Spain)

*[email protected] Keywords: renewable energy, electrochemical oxidation, clopyralid, pesticide The fast growth of population in the last centuries has increased the crops areas and consequently, the use of pesticides to rise the production and drop crop diseases. The massive use of pesticides has let huge areas polluted by these compounds. Most of them are organochloride compounds which have great chemical stability, resistance to biodegradation and high water insolubility [1]. These properties make difficult their mineralization by traditional treatments. Advanced oxidation processes (AOPs), based on the production of hydroxyl radicals (highly strong oxidants), achieve high mineralization efficiencies of organic compounds [2]. Among the wide variety of AOPs the electro-oxidation with Boron Doped Diamond (BDD) anode is one of the most promising techniques. However, this electrochemical process needs electrons as reactive and consequently, electricity. This is the unique and the highest cost of this electrochemical treatment. Taking this into account, the use of renewable energies could become these processes in sustainable and environmental friendly [3]. Nevertheless, renewable energies depend heavily on weather forecast and their production is not constant and continuous. In view of the previous arguments the present work studies the performance of an electrochemical oxidation process electrically supplied by green energies. Solar radiation in Ciudad Real was measured and recorded using a data acquisition systems (LabVIEW). Soils polluted by clopyralid were washed and subsequently, the electrolysis with BDD of the soil washing effluent was carried out. In order to aim the best green energy management for the wastewater treatment, the energy storage and the management of the applied charge density (Ah dm-3) at sunlight or windy hour was studied with the aim of improve the use and exploitation of these renewable resources. References [1] Rodrigo, M.A., N. Oturan, and M.A. Oturan, Electrochemically Assisted Remediation of Pesticides in Soils and Water: A Review. Chemical Reviews, 2014. 114(17): p. 8720-8745. [2] Dewil, R., et al., New perspectives for Advanced Oxidation Processes. Journal of Environmental Management, 2017. 195: p. 93-99. [3] Mook, W.T., M.K. Aroua, and G. Issabayeva, Prospective applications of renewable energy based electrochemical systems in wastewater treatment: A review. Renewable and Sustainable Energy Reviews, 2014. 38: p. 36-46.

Acknowledgments Financial support from the Spanish Ministry of Economy, Industry and Competitiveness and European Union through project CTM2016-76197-R (AEI/FEDER, UE) is gratefully acknowledged. M. Millán wishes to thank to the UCLM for the pre-doctoral contract with the framework of the Plan Propio I+D.

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REMOVAL OF CHLORINATED HYDROCARBONS FROM GASEOUS PHASE USING A COMBINED PROCESS OF ADSORPTION AND ELECTROLYSIS

M. Muñoz Morales, Cristina Saez, Pablo Cañizares, M.A. Rodrigo*

Department of Chemical Engineering, University of Castilla-La Mancha, Avda. Camilo José Cela, 12 13071 Ciudad Real *e-mail: [email protected]

Keywords: adsorption, electrooxidation, Granular Active Carbon (GAC), methanol In recent decades, the development of new and efficient technologies for the removal of chlorinated hydrocarbons in soils and wastewater is a matter of great interest [1]. Sometimes, the high volatility of these pollutants lead to the release of an important amount of these compounds to the air. One of the best technologies to solve this problem is the adsorption onto Granular Activated Carbon (GAC) [2] because it allows to retain the pollutant in a very efficient and fast way. Regeneration of GAC can be carried out by different technologies and in this work, it is described a novel approach. This approach consists of combining the adsorption of chlorinated compounds onto GAC particles with its desorption into methanol to obtain concentrated wastes. Based on previous results obtained with health-related and low solubility molecules, for a further re-use of the same solvent, it was attained an electrolysis with diamond electrodes in a mixture of water and methanol. It was found that the molecule was depleted with a negligible degradation of methanol [3]. To do this, firstly it was evaluated the adsorption isotherms of the chlorinated hydrocarbons to determine the retention capacity using GAC in each solvent. This capacity was very high with clopyralid in water, so this is a good example to make a proof of concept about the developed technology. Then, it is also evaluated the desorption capacity using methanol as solvent to obtain a high concentrated solution to be treated. Afterwards, it was evaluated the removal efficiency of these compounds in aqueous and methanol solution using diamond anodes. It is important to remark the results obtained using methanol as electrolyte because these experiments open the possibility of developing a new process based on the electrolysis of highly concentrated chlorinated hydrocarbons in a non-aqueous media. To shed light to the studied process, oxidant species and intermediates generated were measured to evaluate the mechanism of depletion of pesticides in the different solvents used. Results show that oxidants have an important influence in the degradation of pollutants in methanol solutions and intermediates that are generated in very low concentration are oxidized during the treatment.

References [1] C.M. Dominguez, N. Oturan, A. Romero, A. Santos, M.A. Oturan, Chemosphere. [2] J. Virkutyte, M. Sillanpää, P. Latostenmaa, , Science of The Total Environment, 289 (2002) 97-121. [3] M.A. Rodrigo, N. Oturan, M.A. Oturan, Chemical Reviews, 114 (2014) 8720-8745.

Acknowledgments Financial support from the Spanish Ministry of Economy, Industry and Competitiveness, European Union through project CTM2016-76197-R (AEI/FEDER, UE) and the Spanish Government (Grant Nº FPU16/00067) are gratefully acknowledged.

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DEGRADATION OF CARBENICILLIN IN SECONDARY EFFLUENTS BY PHOTOELECTRO-FENTON WITH AIR-DIFFUSION CATHODES

G.B. Ren1,2, Z.H. Ye1, E. Brillas1, M.H. Zhou2, I. Sirés*1

1Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física,

Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain, 2Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of

Environmental Science and Engineering, Nankai University, Tianjin, 300350, China e-mail: [email protected]

Keywords: air-diffusion electrode, antibiotic, BDD, photoelectro-Fenton, water treatment Carbenicillin (CBN) is one of the most frequently used antibiotics in medical practice due to its strong antibacterial action. However, CBN is incompletely metabolized upon ingestion, leading to its discharge into municipal sewage and the detection of up to several micrograms per liter [1]. The occurrence of CBN in natural aquatic environment may induce antibiotic resistance genes. Therefore, it is necessary to develop more efficient treatment methods to ensure its complete removal from wastewater. Nowadays, the use of electrochemical advanced oxidation processes (EAOPs) for the removal of antibiotics from water bodies attracts much attention. Among the EAOPs, photoelectro-Fenton (PEF) with air-diffusion cathode is the best option to mineralize organic pollutants. It is based on an electrochemical system that promotes the continuous production of H2O2 via cathodic reduction of O2, along with a photoirradiated cell to achieve the continuous regeneration of Fe2+ [2]. However, the performance of PEF for the treatment of CBN from secondary effluents has not been reported yet. In this work, the cathode with the best performance for H2O2 production in a simulated water matrix was selected from various air-diffusion cathodes. The PEF reactor was a 150 mL undivided cell with a 3 cm2 boron-doped diamond (BDD) and 3 cm2 cathode. The experiments were performed with 20.7 mg/L CBN (10 mg/L TOC), which were spiked into the simulated wastewater or real urban wastewater. For comparison, electro-oxidation and electro-Fenton trials were also made. The primary intermediates and inorganic ions were identified by GC-MS and ion chromatography, respectively. References [1] X. Zhou et al., Chem. Eng. J. 341 (2018) 93-101. [2] E. Brillas et al., Chem. Rev. 109 (2009) 6570-6631. Acknowledgements The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU) and the scholarship awarded to G.B. Ren (State Scholarship Fund, CSC, China).

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REMEDIATION OF WASTESWATER BY SEQUENTIAL ADSORPTION-ELECTRO-FENTON TECHNIQUES

M.A. Sanromán*1, A. Díez1, E. Rosales1, M. Pazos1

1Centro de Investigación Tecnolóxico Industrial - MTI, University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain

*e-mail: [email protected] Keywords: Adsorption, Fenton, Ionic liquid, Dyes, Pharmaceutical, Kaolin, Sepiolite The release of pollutants to the environment occurs directly by untreated or not-well treated effluents from industries or also environmental disasters. Different remediation technologies have been proposed for the treatment of these effluents. Among them, adsorption has attracted great attention due to its simplicity and high efficiency. However, the main drawbacks of this process are the expensive cost of the typical adsorbents and the final destination of the spent adsorbent. After adsorption, the adsorbent becomes itself a hazardous waste that must be treated or disposed properly. The recovery of the adsorbent, its subsequent regeneration, and reuse are important issues from economical and environmental point of view [1]. As solution in this study, a sequential combination of adsorption and regeneration process based on electro-Fenton treatment is proposed as a plausible alternative for the removal of pollutants from wastewater and the reuse of the adsorbents. Initially, low-cost adsorbents such as clay materials (kaolin or sepiolite) were evaluated in the removal of several pollutants (ionic liquids, dyes, pharmaceuticals, ...) and the kinetic and isotherm studies were performed. In a second stage, several electro-Fenton processes were tested and compared with conventional Fenton technology for the degradation and removal of the adsorbed pollutants. Then, the reuse of the adsorbents was evaluated by the application of consecutive adsorption-regeneration cycles. Thus, e.g. in the remediation of the ionic liquid 1-butyl, 2,3-dimethylimidazolium chloride using sepiolite, it was determined an adsorption uptake of 9.5 mg/g and the regeneration by electro-Fenton process was possible, being successfully reused for 3 times. Finally, the sequential adsorption-regeneration system was scaled up and modelled so as to evaluate its feasibility in the treatment of industrial effluents. It can be concluded that the problem of the spent adsorbents disposal can be overcome, and the consumption of fresh adsorbents reduced by application of electro-Fenton as regeneration technique. References [1] Rosales, E., Anasie, D., Pazos, M., Lazar, I., Sanromán, M.A. (2018) Kaolinite adsorption-regeneration system for dyestuff treatment by Fenton based processes. Sci.Total Environ. 622-623: 556-562. Acknowledgments This research has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) Xunta de Galicia and ERDF Funds (Projects CTM2017-87326-R and ED431C 2017/47).

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Electrochemical Treatment of Real Wastewater — Effluents with Low Conductivity

Pengfei Ma1,2, Hongrui Ma1, Simona Sabatino2, Alessandro Galia2, Onofrio Scialdone*2

1School of Environment Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China. 2Dipartimento dell’Innovazione Industriale e Digitale, Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università degli Studi di Palermo, Palermo 90128, Italy.

*e-mail: ([email protected] ) Keywords: Real wastewater, Electrochemical oxidation; Wastewater treatments; BDD; Low conductivity; Micro reactors. In recent years, many researches have demonstrated that electrochemical methods offer an attractive alternative to traditional routes for treating wastewaters contaminated by refractory organic pollutants and toxic for microorganisms [1]. Nevertheless, most of the investigations were performed using synthetic wastewater [2]. Hence, it is necessary to study the problems connected to the passage from synthetic wastewater to the real ones. The performances of electrochemical treatment are expected to strongly depend on many factors including the conductivity of the real wastewater, which are characterized by a very large variety of salt content and conductivity [3]. In this work, the treatment of a real wastewater characterized by low conductivity was performed by anodic oxidation at boron doped diamond (BDD) in both microfluidic and undivided conventional cells. The electrolyses carried out in conventional cells without supporting electrolyte were characterized by very high TOC removals but excessively high energetic consumptions and operating costs. The addition of sodium sulphate, as supporting electrolyte, allowed to strongly reduce the cell potentials and consequently the energetic consumptions and the operating costs. However, under various operating conditions, the addition of Na2SO4 caused a lower abatement of the TOC. The best results in terms of both TOC removal, energetic consumptions and operating costs (about 1 €/m3) were obtained using a cell with a very low inter-electrode distance (50 µm) with no addition of a supporting electrolyte. References [1] I. Sirés, E. Brillas, M.A. Oturan, M.A. Rodrigo, M. Panizza, Electrochemical advanced oxidation processes: today and tomorrow. A review, Environ. Sci. Pollut. Res. 21 (2014) 8336–8367. [2] C.A. Martínez-Huitle, S. Ferro, Electrochemical oxidation of organic pollutants for the wastewater treatment: direct and indirect processes, Chem. Soc. Rev. 35 (2006) 1324–1340. [3] A.J.C. da Silva, E.V. dos Santos, C.C. de Oliveira Morais, C.A. Martínez-Huitle, S.S.L. Castro, Electrochemical treatment of fresh, brine and saline produced water generated by petrochemical industry using Ti/IrO2-Ta2O5 and BDD in flow reactor, Chem. Eng. J. 233 (2013) 47–55. Acknowledgments The work was supported by Università di Palermo and Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR).


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EFFECT OF ANODIZATION CONDITIONS ON THE CHARACTERISTICS OF THIN FILM ELECTRODES DEPOSITED ON NANOSTRUCTURED TITANIUM SUBSTRATE

E. Petrucci*1, D. Montanaro1, M. Orsini2, G. Sotgiu2

1 Department of Chemical Engineering Materials & Environment, Sapienza University of Rome, Via

Eudossiana 18, 00184 Rome, Italy 2 Department of Engineering, Roma Tre University, Via Vito Volterra 62, 00146 Rome, Italy

*e-mail: [email protected] Keywords: metal oxide thin film, nanostructured titanium, central composite design, durability

Manganese oxide-based electrodes exhibit promising electrocatalytic activity, a reduced electrogeneration of chlorinated by-products in the presence of chlorides, supercapacitive behaviour and low cost. For this reason, an increasing number of papers deal with their use in a wide range of applications from anodic oxidation to supercapacitors and fuel cells. A major drawback is represented by their limited durability caused by a low adherence of the oxides to the investigated substrates. Nonetheless, the characteristics of these materials encourage further studies to improve both stability and durability by adopting more efficient preparation techniques.

In previous research, by comparing the performance of MnOx films grown on both untreated and microstructured substrates we have verified that the morphological and electrochemical properties of the electrodes take advantage of increased texture of electrode surface [1].

Recently, a new approach to produce anode materials has been developed and applied. The method involves the oxide deposition on substrates modified at a nano-scale with significant increase in the life time of the electrode without impacting the electrocatalytic properties [2]. The enhanced performance can be attributed either to the increase in the electrode surface area or to the improved inclusion of the oxide particles inside the nanostructures.

The present work investigates the possibility to improve the durability of electrodes obtained by deposition of a mixed oxides thin film on a nanostructured titanium substrate by optimizing the main operative conditions of anodization procedure employed in the nanostructured material. The manganese and ruthenium mixed oxide layer has been obtained by thermal decomposition of alcoholic solutions of the precursor salts. The electrodes obtained have been characterized in terms of morphological and electrochemical properties by scanning electron microscopy (SEM), cyclic voltammetry (CV), polarization curves. The factors investigated were fluoride concentration (0.25-0.75 %), anodization voltage (15–45 V) and anodization time (45-135 min). The response variable was the durability of the anode assessed by accelerated life tests. [1] G. Sotgiu, L. Tortora, and E. Petrucci, E. J. Appl. Electrochem. 45 (2015), 787-797. [2] H. An, H. Cui, W. H. Zhang, J. Zhai, Y. Qian, X. Xie, Q. Li, Chem. Eng. J., 209 (2012), 86-93.

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PERFORMANCE OF ACTUAL COMERCIAL CELLS FOR THE ELECTROCHEMICAL PRODUCTION OF PERCHLORATES FROM BRINES

I. Moraleda, J. Llanos*, C. Sáez, M.A. Rodrigo, P. Cañizares

Chemical Engineering Department, University of Castilla-La Mancha,

Edificio Enrique Costa Novella. Av. Camilo José Cela nº 12, 13071 Ciudad Real, Spain *[email protected]

Keywords: Electrosynthesis, Oxidants, Perchlorates, Diamond electrodes. During the recent years, many works have been focused on the study of electrochemical oxidation with diamond anodes as an alternative technology for the treatment of industrial wastes and for the electrosynthesis of oxidants. The good properties of this electrode, higher chemical and electrochemical stability and the high overpotential for water electrolysis, has allowed achieving great results in comparison to other electrodes material. For this reason, the production of oxidants such as peracetic acid [1, 2] or perchlorates [1, 3] is a matter of the major importance for the Chemical Industry. Among these oxidants, perchlorate salts are used in pyrotechnics, in manufacture of matches, munitions and in the chemical analytical industry. The main aim of this work is to compare the performance of different commercial cells in the electrochemical production of perchlorate with conductive boron doped diamond, using as raw material highly concentrated chloride solutions (from 1M to 2M NaCl). The use of this concentration range pursues two main aims: 1) to focus on the typical concentration of brines (for example of rejection streams of sea water reverse osmosis) thus serving as a way of revalorization of this waste; 2) to increase the concentration of perchlorate to a concentration level industrially valuable. Different commercial cells (from Condias GmbH and Adamant Technologies) were tested and the results obtained compared in terms of maximum perchlorate concentration, efficiency and specific power consumption. Moreover, the effect of several operation parameters such as current density and chlorine concentration was studied. References [1] P. Cañizares, C. Sáez, A. Sánchez-Carretero, M. A. Rodrigo, Synthesis of novel oxidants by electrochemical technology (2009) 39:2143-2149. [2] J. Llanos. I. Moraleda, C. Sáez, M. A. Rodrigo, P. Cañizares, Optimization of a cell for the electrochemical synergistic production of peroxoacetic acid, 260 (2018) 177-183. [3] A. Sánchez-Carretero, C. Sáez, P. Cañizares, M. A. Rodrigo, Electrochemical production of perchlorates using conductive diamond electrolyses, 166 (2011) 710-714. Acknowledgments The financial support from the Spanish Ministry of Economy, Industry and Competitiveness and European Union through project CTM2016-76197-R (AEI/FEDER, UE) is gratefully acknowledged.

EP-O1

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COMBINATION OF BIO-ELECTROCHEMICAL AND ELECTROCHEMICAL TECHNOLOGIES AS A READY-TO-USE SOLUTION FOR FOOD INDUSTRY

WASTEWATER TREATMENT

Patricia Zamora1, Yeray Asensio1, Sara Tejedor2, Patricia Fernández4, Juan M. Ortiz*2, Victor M. Monsalvo1, Juan F. Ciriza4, Frank Rogalla1, Abraham Esteve Núñez2,3

1Aqualia, Innovation and Technology Department, Av. del Camino de Santiago 40, 28050, Madrid, Spain, 2Instituto Madrileño de Estudios Avanzados IMDEA Agua, Av. Punto Com 2, 28805 Alcalá de Henares, Spain, 3Departamento de Química, Universidad de Alcalá, Alcalá de Henares, 28805, Alcalá de Henares, Madrid (Spain), 4Mahou-San Miguel, C. Titán 15, 28045, Madrid, Spain

e-mail: [email protected]

Keywords: waste water treatment, electrocoagulation, circular economy.

Food industry processes are accompanied by the production of high flow rates of wastewater characterized by high concentrations of easily biodegradable organic matter, but also high concentrations of suspended solids and nutrients (N and P) being necessary the implementation of suitable wastewater treatments to accomplish with the European and National effluent discharge limits. In this context, the ANSWER project (LIFE15 EN/ES/000591) aims to demonstrate the technical and economic feasibility of the integration of electrochemical, electrocoagulation (EC), and bio electrochemical technologies, Fluidized bed bio-electrochemical reactor (FBBR), at pilot scale for the efficiently treatment of agro-industrial wastewaters. Energetically efficient wastewater treatment has been successfully achieved removing up to 96% of the suspended solids, 98% of the nutrients at best conditions (N and P) and up to 96 % of the soluble COD accomplish with the effluent discharge limits with low energy consumption.

Figure 1. Diagram of the proposed technology in ANSWER project.

References [1] S. Tejedor-Sanz, J.M. Ortiz, A. Esteve-Núñez, Merging microbial electrochemical systems with

electrocoagulation pretreatment for achieving a complete treatment of brewery wastewater, Chem. Eng. J. 330 (2017) 1068–1074. doi:https://doi.org/10.1016/j.cej.2017.08.049.

Acknowledgement: Authors acknowledge ANSWER project (LIFE15 EN/ES/000591) for the economic support.


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RGB VIDEO ELECTROCHEMISTRY TO STUDY THE EFFECT OF OHMIC DROP ON THE LECTROCHROMIC RESPONSE OF CONDUCTING POLYMERS

J. Agrisuelas*, J.J. García-Jareño, F. Vicente

Departament de Química Física. Facultat de Química. Universitat de València.

C/ Dr Moliner 50 46100 Burjassot (València) *e-mail: [email protected]

Keywords: electrochromic polymers, ohmic drop, digital video, RGB video electrochemistry

The electrochromic conducting polymers have attracted the interest of researchers due to their wide technological applications [1]. The characterization of large electrochromic electrodes proves difficult by classical spectroscopic techniques since the analysis is focused on relatively small electrode areas limited by the light beam cross-section. Digital video allows us to analyze the complete electrochromic area during an electrochemical experiment with a good resolution [2]. Here, we present new insights of RGB video electrochemistry for the analysis of color changes during some electrochemical experiments using poly(o-toluidine), a polyaniline-derivative, deposited on narrow, long transparent indium-tin oxide (ITO) electrodes (0.5×2.5 cm2). This electrode geometry increases the electrical resistance along the electrode surface. Thus, we can study the effect of the ohmic drop on the electrochromic reactions of poly(o-toluidine) films. The spatiotemporal analysis of color intensity in the red, green and blue components of the acquired images from digital video allows us to obtain the characteristic fingerprint of color evolution. Coating fraction and apparent electromonochromatic coefficients were calculated to estimate the relative film thickness or to convert the adimensional RGB intensities to electrochemical currents [3]. The methodology here exposed can be used to characterize electrochemical response of electrochromic devices for uses in innovative investigations and fast quality controls of electrochromic devices or modified electrodes at low cost. References [1] X. Lv, W. Li, M. Ouyang, Y. Zhang, D.S. Wright, C. Zhang, Polymeric electrochromic materials with

donor-acceptor structures, J. Mater. Chem. C. 5 (2017) 12–28. [2] J. Agrisuelas, J.J. García-Jareño, E. Perianes, F. Vicente, Use of RGB digital video analysis to study

electrochemical processes involving color changes, Electrochem. Commun. 78 (2017) 38–42. [3] J. Agrisuelas, J.J. García-Jareño, F. Vicente, Spatiotemporal colorimetry to reveal electrochemical

kinetics of poly(o-toluidine) films along ITO surface, Electrochimica Acta. 269 (2018) 350–358. Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R


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BISMUTH AND TIN NANOPARTICLES AS ELECTROCATALYSTS FOR THE ELECTROCHEMICAL DENITRIFICATION OF WATER

Ignacio Sanjuán*, Leticia García-Cruz, José Solla-Gullón, Eduardo Expósito, Vicente Montiel

Grupo de Electroquímica Aplicada y Electrocatálisis, Instituto Universitario de Electroquímica, Departamento de Química Física, Universidad de Alicante, Apdo. 99, Alicante 03080, Spain.

*e-mail: [email protected] Keywords: Nitrate, nanoparticles, bismuth, tin, water treatment, electrochemical denitrification.

Contamination of groundwaters with nitrate (NO3-) is becoming an important global issue due to the use of nitrogen-based fertilizers in intensive agriculture practice. NO3- may imply serious health problems because can be reduced to nitrite (NO2-) in living organisms, which can cause metahemoglobinemia, liver damage or even cancer. For this reason, the legislation of different countries limits considerably the NO3- concentration in drinking water [1].

In this regard, electrochemical denitrification is a very promising technique to remove NO3- from water because presents some advantages over other available technologies like reverse osmosis or ion exchange membranes: no chemicals addition, no sludge production, environmental compatibility and inexpensive infrastructure. The electroreduction of NO3- pursues its total conversion to innocuous N2 but other secondary products such as NxOy, NH2OH, NH3 and NH2NH2 can be obtained. In this sense, according to literature, the most active and selective electrocatalysts for this process are combinations of Pd or Pt with at least one more metal (PdSn, PtCu, PtSnAu…) but they are not cost-effective for practical applications [1]. Conversely, cheap metals like tin (Sn) and bismuth (Bi) have also shown interesting rates of reduction and selectivity to N2 [2].

In this contribution, the electrocatalytic activity of Bi, Sn and Sn-Bi nanoparticles has

been evaluated for the electrochemical denitrification process. For that, the different nanoparticles (10 - 12 nm) have been synthesised and supported onto carbon black with a simple, fast and scalable method at room temperature. The prepared materials have been characterised by TEM, XRD and XPS and, subsequently, air-brushed onto a Toray Carbon Paper. Voltammetric studies and electrolysis trials have been carried out in order to test the nanoparticulated materials for the electrochemical denitrification process, showing good stability and interesting electrocatalytic performance.

References [1] M. Duca, M. T. M. Koper, Energy Environ. Sci., 5 (2012), 9726–9742. [2] I. Katsounaros, M. Dortsiou, G. Kyriacou, J. Hazard Mater., 171 (2009), 323–327. Acknowledgments I. Sanjuán would like to acknowledge the scholarship granted and the human resources provided by the University of Alicante and the company Aguas de Valencia, S.A.


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REMOVAL OF ANTIBIOTIC PENICILLIN G BY CONDUCTIVE-DIAMOND ELECTROCHEMICAL OXIDATION

S. Cotillas*1, E. Lacasa1, M. Herráiz1, C. Sáez2, P. Cañizares2, M.A. Rodrigo2

1Department of Chemical Engineering. School of Industrial Engineering. University of Castilla-La Mancha. Avenida de España S/N, 02071. Albacete. Spain, 2Department of Chemical Engineering.

Faculty of Chemical Sciences and Technologies. University of Castilla-La Mancha. Avenida Camilo José Cela 12,13005. Ciudad Real. Spain.

*e-mail: [email protected] Keywords: electrolysis, diamond, penicillin g, urine The presence of antibiotics in wastewater has become an important concern for scientific community because of these compounds are the main responsible of the occurrence of antibiotic resistant bacteria. The present WWTPs are not able to remove traces of antibiotics in industrial and domestic effluents and, for this reason, it is necessary to develop novel clean and efficient technologies that allow a complete removal of antibiotics in wastewater before discharge to the environment. In this context, conductive-diamond electrochemical oxidation (CDEO) has been proved efficient for the removal of several organics such as pesticides, hormones or personal care products, reaching the total mineralization of the organic matter. During this process, higher concentrations of hydroxyl radicals and other oxidants are electrochemically generated over the anode surface and they are the main responsible species of the degradation process. With this background, the main aim of the present work is to evaluate the application of CDEO for the removal of antibiotics in wastewater. Penicillin g has been selected as model of antibiotic because it presents a broad spectrum of action and it has bactericide properties. The influence of the supporting electrolyte (Na2SO4, NaCl, Na2CO3) was assessed at current densities within the range 10-100 mA cm-2. Likewise, the removal of penicillin g was studied in synthetic urine media because of the human excretion is the main source of pharmaceuticals and their concentration is higher in urine. Results show that it is possible to attain a complete removal of penicillin g and a total mineralization of the organic matter present in wastewater by electrolysis with diamond anodes. This is due to the in situ electrochemical production of powerful oxidants from the oxidation of the ions present in the effluent. These species attack to the organic matter, favouring a complete removal. It is important to highlight that synthetic urine presents other organics in its composition such as urea, creatinine and uric acid which are also degraded during the treatment. Finally, the process efficiency is clearly influenced by the current density, being higher when applying low values (10 mA cm-2). Acknowledgments This work has been supported by the Spanish Government (MINECO/FEDER, U.E.) through the project CTM2016-76197-R. JCCM is also acknowledged for the postdoctoral grant (SBPLY/16/180501/000404) awarded to Dr. Salvador Cotillas.


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COLOR STANDARD DEVIATION AS A TOOL TO IDENTIFY THE FORMATION OF PASSIVE LAYERS ON THE ELECTRODE SURFACE.

J.J. García-Jareño*, J. Agrisuelas, F. Vicente



Keywords: metal deposition, standard deviation, digital video, RGB video electrochemistry

Metal corrosion takes place by complexes mechanisms where adsorption of different species on the electrode surface, the appearance of intermediate species or the formation of different layers on the electrode affect the rate of corrosion. All these processes could involve a color change of the electrode surface; therefore, in situ spectroscopy could be helpful identifying these processes. However, classical spectroscopy gives only information about a small electrode region surface and no idea about the homogeneity of the electrode surface is obtained. For that purpose, it is a better choice the image analysis of the electrode surface. Recently, we have proposed recording video during the electrochemical processes and then extracting frames at each time interval and analyzing the Red, Blue and Green (RGB) color histograms [1]. By RGB intensities it is possible discerning about 16M colors and then a good identification of the color surface is possible. Other parameters of our interest are standard deviation for each color, which could give an excellent idea about the homogeneity of the electrode surface [2]. In a homogeneous surface color, standard deviation reaches minimum values, while if color changes at any part on the electrode surface, this region should appear as maximum standard deviation. Therefore, during a color change standard deviation evolves from a minimum (color 1) to a maximum (color 1 and 2 are present) and finally a new minimum (color 2). We analyze color changes of a resistive black composite electrode during electrodeposition of Cu and electrodissolution of Cu [3]. Different maximum values of standard deviation are explained and interpreted as the formation of different layers on the electrode surface and allows quantifying the rate of surface covering or the rate of surface stripping during electrochemical processes. References [1] J. Agrisuelas, J.J. García-Jareño, E. Perianes, F. Vicente, Use of RGB digital video analysis to study

electrochemical processes involving color changes, Electrochem. Commun. 78 (2017) 38–42. [2] J. Agrisuelas, J.J. García-Jareño, F. Vicente, Spatiotemporal colorimetry to reveal electrochemical

kinetics of poly(o-toluidine) films along ITO surface, Electrochimica Acta. 269 (2018) 350–358. [3] J. Navarro-Laboulais, J. Trijueque, J.J. García-Jareño, F. Vicente, Ohmic drop effect on the

voltammetric behaviour of graphite + polyethylene composite electrodes, J. Electroanal. Chem. 422 (1997) 91–97.



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EFFECT OF ANODIZING BATH COMPOSITION AND ELECTRIC PARAMETERS ON PLASMA ELECTROLYTIC OXIDATION PROCESSES FOR PRODUCING COATING

ON 7075 AL ALLOY Francesco Di Franco*1, Paolo Ceraulo1, Ehsan Akbari2, Keyvan Raeissi2, Monica Santamaria1

and Amin Hakimizad2 1Electrochemical Materials Science Laboratory, DICAM, University of Palermo, Viale delle Scienze,

90128 Palermo, Italy 2Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156–83111, Iran*

e-mail: [email protected] Keywords: Plasma electrolytic oxidation; 7075 Al alloy; Pulsed waveforms; Potassium titaniumoxalate; Tribocorrosion. Plasma electrolytic oxidation (PEO), also known as micro arc oxidation (MAO) or anodic spark deposition (ASD) is an anodizing process assisted by plasma discharges for producing thick oxide films on surface of valve metals and light alloys. PEO is usually used for metals such as titanium, magnesium, tantalum, zirconium, aluminum and their alloys, which provide stable oxides in aqueous media. Such oxide layers show controllable morphology and composition, excellent bonding strength with substrate, good electrical and thermal properties, high micro-hardness and suitable wear and corrosion resistance. PEO process can be carried out using direct current (DC), alternating current (AC) or pulsed DC regimes. The incorporation of nano-particles in the oxide layer structure improves its tribological and corrosion behavior, and also, increases its hardness and adhesion to the substrate. Many industries such as machinery, textile and printing are interested on Al2O3/TiO2 composite coatings due to their high hardness, excellent wear and corrosion properties, as well as high thermal and chemical resistance. In the present work we study the possibility of preparing Al2O3/TiO2 composite coatings on 7075 Al alloy by addition in the electrochemical bath of potassium titanium oxalate (PTO), 𝐾𝐾2[𝑇𝑇𝑇𝑇𝑇𝑇(𝐶𝐶2𝑇𝑇4)2] using a pulsed DC regime. During the anodic step an electrochemical potential gradient drives anions toward the metal/coating interface, while the alkalinisation due to H2 evolution during the cathodic step induces the TiO2 precipitation according to the following chemical reaction:

𝑇𝑇𝑇𝑇𝑇𝑇(𝐶𝐶2𝑇𝑇4)22− + 2𝑇𝑇𝑂𝑂− → 𝑇𝑇𝑇𝑇𝑇𝑇2 ∙ 𝑂𝑂2𝑇𝑇 + 2(𝐶𝐶2𝑇𝑇4)2− with the consequent TiO2 formation inside the coating. The effects of waveform (unipolar and bipolar) on structure and corrosion properties of Al2O3/TiO2 composite coatings on 7075 Al alloy are investigated. Scanning electron microscopy was employed to study the surface morphology of the coating as a function of the oxidation conditions as well as to examine their cross sections, while energy dispersive spectroscopy (EDS) confirmed the incorporation of TiO2 inside the coatings. The corrosion resistance of coatings was investigated in 3.5 % NaCl solution (pH 4) using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Tribocorrosion experiments were performed using SiC ball under the load of 1 N for 3600 s at 1 Hz oscillating frequency. The variation of open circuit potential (OCP) during tribocorrosion test in 3.5 % NaCl solution (pH 4) and the volume loss of the coatings were reported.

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MULTISCALE ELECTROCHEMICAL CHARACTERIZATION OF THE CORROSION INHIBITION CHARACTERISTICS OF A NOVEL SCHIFF BASE

R.M. Souto*1,2, M. Talebian3, B.M. Fernández-Pérez1, M. Atapour3, K. Raeissi3

1Department of Chemistry, Universidad de La Laguna, La Laguna (Tenerife), Spain

2Institute of Materials Science and Nanotechnology, La Laguna (Tenerife), Spain 3Department of Materials Engineering, Isfahan University of Technology, Isfahan, Iran

*e-mail: [email protected] Keywords: scanning vibrating electrode technique, corrosion inhibition, Schiff base, galvanic corrosion, polarization. The ability of a new synthesized anionic carboxylic Schiff base, sodium (E)-4-(4-nitrobenzylideneamino)benzoate (SNBB), as corrosion inhibitor of various metals in neutral NaCl aqueous solutions was established using potentiodynamic polarization and the scanning vibrating electrode technique (SVET), in order correlate macroscopic behaviour of the materials with the detection of localized ionic current distributions over the metal surfaces originated from corrosion reactions. It is shown that SNBB effectively inhibit corrosion processes on F111 steel at both OCP and under anodic polarization conditions within the passive regime of the material, and the localized ionic flow distribution occurs almost exclusively above the strip immersed in the SNBB-free test solution. Analogously, the SVET analysis of unbiased 304 steel sheets both in the absence and presence of SNBB have been observed only to contain the background noise at its corresponding OCP values. The good inhibition performance of SNBB against pitting corrosion of 304 steel was further confirmed for samples subjected to anodic polarization, exclusively revealing very localized and limited local anodic activities at randomly distributed points that can be satisfactorily correlated to metastable pitting events in the potential range comprised between the pitting potentials of the inhibitor-free and the inhibitor-containing test solution. Finally, in the case of an iron–copper galvanic couple immersed in the test solution in absence of SNBB, the anodic oxidation process is observed to be initiated exclusively on the iron sample, and it takes place in a localized manner. The electrochemical activity of iron is observed to greatly increase upon establishing the galvanic coupling condition between the two metals. Conversely, the electrochemical reactions are inhibited at the presence of the SNBB in both individual and galvanic pair conditions due to the formation of stable chelates on the iron surface.

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Use of TiO2 nanotubes for acetaminophen photoelectrochemical degradation

R. Sánchez Tovar, J. Borràs-Ferris, M.E. Blasco-Tamarit, R.M. Fernández-Domene, B. Lucas-Granados, J. García-Antón

Ingeniería Electroquímica y Corrosión, Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental, Universitat Politècnica de València. Camino de Vera s/n, 46022, Valencia, Spain

*[email protected] Keywords: TiO2, nanotube, photoelectrocatalysis, acetaminophen Nowadays, a great effort has been made in the degradation of pharmaceuticals, which are considered as emerging pollutants. Among them, acetaminophen is one of the most found in rivers, ambient waterways, and the influents and the effluents of wastewater treatment plants. Additionally, it could induce liver and kidney damage; this is the reason why it has attracted the interest of researchers. In this work novel TiO2 nanotubes obtained by electrochemical anodization under hydrodynamic conditions has been used as photocatalyst for photoelectrochemical (PEC) degradation of acetaminophen. Additionally, the pH influence as operation parameter during the acetaminophen degradation has been also analysed. To characterize the nanostructures, Field Emission Scanning Electron Microscope (FE-SEM) and Raman Confocal Laser Microscopy has been used. Moreover, the kinetic study has been possible by means of UV- visible spectroscopy and chemical oxygen demand (COD). According to the results, acetaminophen photodegradation is enhanced at pH 3 and working with TiO2 nanotubes anodized rotating the electrode at Reynolds 600 (Figure 1).

Figure 1. UV absorption spectra obtained during PEC degradation of 40 ppm of acetaminophen at different reaction times.

Acknowledgments: Authors thank to the financial support to the Ministerio de Economía y Competitividad (Project code: CTQ2016-79203-R) and for the co-finance by the European Social Fund.

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TESTING THE ELECTROCATALYTIC ACTIVITY OF CARBON NANOMATERIALS

A. Heras*, A. Colina, J. Garoz-Ruiz, P. López, F. Olmo

Department of Chemistry, Universidad de Burgos, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain. *e-mail: [email protected]

Keywords: Spectroelectrochemistry, carbon nanotubes, graphene It is widely known that most of the carbon nanomaterials (CNMs) show electrocatalytic properties very interesting for electroanalysis. However, these properties are highly dependent on the type and structural features of these CNMs. To test and determine the best CNM for a specific application, their electrocatalytic properties are usually tested in consecutive experiments, by comparing the electrochemical response of the native working electrode (WE) and that of the electrode modified by different CNMs. In this work, a new methodology is proposed taking the advantages of UV/Vis absorption spectroelectrochemistry (UV/Vis-Abs-SEC). Therefore, a novel SEC platform (Fig. 1) is fabricated for the simultaneous comparison of the electrocatalytic responses of different materials in one unique electrode and in a single experiment. As a proof of concept, the WE used in this work consists of a highly oriented pyrolytic graphite (HOPG) electrode whose surface has been partially modified by a CNM: single walled carbon nanotubes (SWCNTs) or graphene (G). This electrode is placed in the UV/Vis-Abs-SEC platform in which two different reflection probes are able to sample separately a specific part of the WE surface. One of these reflection probes samples the electrochemical process occurring on the bare HOPG surface while the other one the same electrochemical process that takes place on the CNM-HOPG modified surface. The experimental results show that, electrochemically, a mixed response of the processes occurring in the two parts of the WE is obtained. Conversely, each absorptometric signal supplies information exclusively related to the reaction occurring in the region of the electrode that is sampled by the corresponding optical fibre probe. In this way is possible to test and compare in a single experiment the electrocatalytic properties of different materials.

Fig. 1. Scheme of the UV/Vis-Abs-SEC platform

Acknowledgments Financial support from Ministerio de Economía y Competitividad (CTQ2017-83935-R, CTQ2014-55583-R, CTQ2015-71955-REDT) and Junta de Castilla y León (BU033-U16) is gratefully acknowledged.

HOPG

Reflection probes

RE CE

CNM

Solution

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FORMATION OF IRON OXIDE NANOSTRUCTURES FOR ELECTROCHEMICAL APPLICATIONS: EFFECT OF ELECTROLYTE TEMPERATURE DURING

ANODIZATION

B. Lucas-Granados*, R. Sánchez-Tovar, R. M. Fernández-Domene, J. García-Antón

Ingeniería Electroquímica y Corrosión (IEC). Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental (ISIRYM). Universitat Politècnica de València. Camino de Vera s/n, 46022 Valencia,

Spain *e-mail: [email protected]

Keywords: iron oxide, nanostructure, electrochemical anodization, electrolyte temperature, water splitting. Iron oxide nanostructures have emerged as interesting materials for being used as photocatalysts in different electrochemical applications such as water splitting. There are different methods to synthesize nanostructures, among them electrochemical anodization is an attractive option since it is a simple method that allows the fabrication of the nanostructures directly on the metallic substrate. In this case, the material can be directly used as photocatalyst without needing an additional step to join the nanostructure to the metallic substrate, which in fact reduces the cost of the process and the contact resistance between the nanostructure and the substrate. Electrochemical anodization permits high control of the obtained nanostructures by varying different parameters. One of the determining parameters of the process is electrolyte temperature. In this work, electrolyte temperature is studied and results revealed that it significantly modified the morphology of the synthesized nanostructures, which in turn resulted in a modification of their electrochemical properties. Tests were carried out at electrolyte temperatures of 25, 40, 50 and 60 ⁰C, under both stagnant and hydrodynamic conditions (Figure 1). Nanostructures were electrochemically and photoelectrochemically characterized by different techniques in order to evaluate their properties.

Figure 1. Iron oxide nanostructures obtained by electrochemical anodization under hydrodynamic conditions (1000 rpm) at different electrolyte temperatures. The authors would like to express their gratitude for the financial support granted by the Ministerio de Economía y Competitividad (Reference: BES-2014-068713 and Project CTQ2016-79203-R), for its help in the Laser Raman Microscope acquisition (UPOV08-3E-012) and for the co-finance by the European Social Fund.

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DESIGN OF PHOTO-ELECTROCHROMIC SMART DEVICES BASED ON SPIROPYRAN-MEROCYANINE SYSTEM.

S. Santiago*, G. Guirado*

Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, 08193-Bellaterra,

Barcelona. *e-mail: [email protected]; [email protected]

Keywords: photoelectrochromism, spirobenzopyrans, molecular switches, electrochromic devices. Nowadays, the design of molecular switches is a topic of great importance for the construction of novel dynamic materials. One of the most promising families of molecular switches are spirobenzopyran derivatives due to its versatility and conversion to several stable or metastable states by applying different external stimulus. It is well-known that those compounds could be reversibly converted from its Spiro form (SP, closed isomer, pale yellow color, OFF state) to a Merocyanine form (MC, open isomer, pink color, ON state) through an isomerization mechanism upon irradiation at specific wavelengths (Figure 1) [1]. Despite of the photochromic properties of spirobenzopyrans derivates have been widely investigated, the establishment of its electrochromic behavior is scarcely studied [2]. Hence, the aim of this study is to demonstrate that the mechanism of isomerization of the spirobenzopyran derivative 1′,3′-dihydro-1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-(2H)-indole can undergo bidirectional switching by applying exclusively an electrical stimulus. The current work would also show the development of smart and flexible photo-electrochromic devices (P-ECD) using ion gels materials as green electrolytes. These materials can be easily cut and laminated on layers being potentially attractive for printed electronics applications, such as smart ECDs. References [1] Feringa, B. L. Molecular Switches. Wiley-VCH, Weinheim, 2001. [2] Ivashenko, O.; van Herpt, J. T.; Rudolf, P.; Feringa, B. L.; Browne, W. R. Chem. Commun. 2013, 49,

6737.

Acknowledgments This work was supported by the Agency of Management of University and Research Grants of the Generalitat de Catalunya (program RIS3CAT, Producte Grant SEAMLESS ref.: 2016PROD00114) through ERDF (FEDER) Investment and Growth Operational Programme ‘Catalonia’ 2014-2020.

hν1 / e-

hν2 / e-

Figure 1: Photoelectrochromic response of a smart iongel based on spirobenzopyran derivatives



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AMINOCUMULENE DERIVATIVE ON THE ELECTROCHEMICAL PERFORMANCE OF CARBON BASED FILMS

A. Gerasimova2, L. García-Cruz1, A.V. Melezhik2, O.V. Alekhina2, V. Montiel1, A.G. Tkachev2,

J. Iniesta*1

1Institute of Electrochemistry, Alicante University. Carretera de San Vicente del Raspeig, 03080 Alicante, Spain.

2Tambov State Technical University, Russian Federation, Sovetskaya str., 106, 392000, Tambov, Russian Federation. *e-mail: [email protected]

Keywords: aminocumulene, carbonaceous films, carbon dispersion, CO2 reduction, sensors Nowadays, carbon-based electrodes are vital for many electrochemical applications due to their exceptional properties regarding mechanical, chemical stability, relative high conductivity and even biocompatibility. For instance, several allotropic forms of carbon such as carbon nanotubes and graphene have been utilized in electrochemical sensing of biological markers. In addition, they have already demonstrated to be promising free-metal electrocatalysts for CO2 reduction and for water oxidation. However, long term stable carbon dispersions are difficult to achieve. This fact compromises the accomplishment of homogeneous carbon-based inks and consequently, the good distribution of carbon material on electrode surface and, ultimately, its catalytic performance. Accordingly, we present here carbon materials with sp-hybridization, namely cumulene [1,2], not only as an alternative to metal electrocatalysts, but also as a highly dispersant agent of other allotropic carbon forms in aqueous solutions. Concretely, in this work, we report the synthesis of the aminocumulene derivative i.e., H2N-CH=C=С=CH-NH2 (AC) with two end capping amino groups. Different dispersions based on the mixture of AC with either distinct oxygen functionalized carbon nanotubes or p-benzoquinone derivative carbon material were prepared under powerful sonication. Later, carbon films were performed by drop casting or by simple painting technique onto carbon supports for further characterization by SEM, XRD and XPS. Also, the electrochemical behaviour of the AC-containing carbon films was explored as a function of pH, and in the presence of outer and inner-sphere electron transfer probes. Moreover, cyclic voltammetry response of different AC-based films was explored as a function of the carbon material in order to correlate the electron transfer process with N-loading in carbonaceous films. Our findings reveal that these free-metal catalytic films can be considered as potential electrocatalysts for CO2 reduction, aside from enhancing the electron transfer rate of several electroanalytical processes of interest. References [1] R. Kuhn, K. Wallenfels, Ber. Dtsch. Chem. Ges., 1938, 71, pp. 783–790 [2] K. Brand, Ber. Dtsch. Chem. Ges., 1921, 54, pp. 1987–2006.

Acknowledgments The authors are grateful to the Spanish MINECO through the protect CTQ2016-76231-C2-2-R.

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SELF- SUPPORTED ARTIFICIAL MUSCLES, FOR MICROROBOTIC´S APPLICATIONS

Laura Valero*1,2, Toribio F. Otero2, Samuel Beaumont2, Javier Salas1

1 Universidad Autónoma del Estado de México, Engineering School, Toluca 50000 México

2Universidad Politécnica de Cartagena, Laboratory of Electrochemistry, Intelligent Materials and Devices, 30203, Cartagena, Spain

*e-mail:[email protected]

Keywords: Artificial muscles, Polymeric sensing actuator, Polymeric engineering applications

Natural muscles sense while working mechanical, thermal or chemical working conditions [1]. Most of the efforts trying to clarify this dual activity have been focused on the physical localization of the different sensors working in a muscle [2,3]. Sensing and tactile artificial muscles fabricated with polymeric electroactive materials replicate haptic muscles [3]. When they work a constant initial oxidation state of the muscle material to a different constant final oxidation state, (moving always between the same initial and final positions) driven by reversible electrochemical reaction. Artificial muscles, actuators or soft motors generating reversible movements are robust, reliable and reproducible motors. Artificial muscles transduce electrical energy into mechanical through electrochemical reactions of the constitutive polymeric chain. The evolution during the actuation of both, the muscle potential and the consumed electrical energy follow a linear dependence, which allow the construction and theoretical description of artificial devices. Muscle movement is controlled by the current flow and thus the direction of current flow controls the direction of the movement. The consumed specific charge controls the displacement amplitude [1].

Here, the ability of artificial muscles to work as integral elements of electrochemical mechanical devices, and possible uncertainties of movement and speed control, also has been evaluated Stress tests, average life time and its simultaneous sensor / actuator capacity, mechanical fatigue tests, in order to potentiate its application to different areas of knowledge. It shows the potential capacity to work and assemble them for microrobot design, focused on specific tasks

References. [1] T. F. Otero, Conducting Polymers: Bioinspired Intelligent Materials and Devices, RSC, 2015. [2] T. F. Otero and M. T. Cortes, Adv. Mater., 2003, 15, 279–282. [3] J. G. Martinez, T. F. Otero, C. Bosch-Navarro, E. Coronado, C. Marti-Gastaldo and H. Prima-Garcia, Electrochimica Acta, 2012, 81, 49–57.

Acknowledgments Authors acknowledge financial support from the Seneca Foundation project 19253/PI/14. México Government UAEM (Universidad Autónoma del Estado de México) – CONACYT and COMECYT (Consejo Mexiquense de Ciencia y Tecnología))

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ELECTROGRAFTING OF ARYL DIAZONIUM SALTS ON HOPG. A SUITABLE SYSTEM FOR THE ELECTRODEPOSITION OF METALLIC NANOPARTICLES.

M. C. Rodríguez González, P. Carro, A.H. Creus*

Área de Química Física, Departamento de Química, Facultad de Ciencias, Universidad de La Laguna

(ULL), Instituto de Materiales y Nanotecnología (IMN), 38200-La Laguna, Tenerife, Spain. *e-mail: [email protected]

Keywords: electrodeposition, electrografting, aryl diazonium films, metallic nanoparticles Electrodeposition of metallic nanoparticles on carbon-based substrates is of great interest in Nanotechnology and Nanoscience fields. Highly Oriented Pyrolytic Graphite (HOPG) is an interesting surface because it is a material closely related with other carbon materials like graphene or carbon nanotubes and due to its suitability to be studied by Scanning Probe Microscopies (SPM). It is known that metallic electrodeposition on HOPG has many disadvantages. Metallic nanoparticles grow mainly on steps and defects and particle-surface adherence on the basal plane is very low. Taking into account these facts it is clear that HOPG surface functionalization could improve the efficiency of the process and the stability of the electrodeposited nanoparticles. Electrografting of aryl diazonium films is the most common strategy to modify carbon surfaces.1 This modification leads to an homogeneous film on steps and basal plane of the HOPG surface. By controlling the film thickness to obtain a layer with good charge-transfer properties,2 metallic electrodeposition can be enhanced.3

In this work, aryl diazonium-based films with different thickness were electrografted on HOPG surfaces. These films were deeply characterized using different types of Atomic Force Microscopy (AFM) for obtain topographical information in the nanoscale. Modified surfaces were used to carry on the electrodeposition of metallic nanoparticles as model system to study the nucleation and growth. After modification of the HOPG surface with a submonolayer, the resultant surface becomes a suitable electrode on which the nucleation and growth of electrodeposited nanoparticles were highly favored.3 Homogeneously distributed hemispherical nanoparticles grow only in the areas covered by the organic monolayer leaving free the clean HOPG zones. References [1] D. Bélanger, J. Pinson. Chem. Soc. Rev. 2011, 40, 3995–4048. [2] T. Menanteau; E. Levillain; A.J. Downard; T. Breton. Phys. Chem. Chem. Phys., 2015, 17, 13137-13142 [3] M.C.R. González, A.G. Orive, R.C. Salvarezza, A.H. Creus. Phys. Chem. Chem. Phys., 2016, 18, 1953-1960 Acknowledgments: M. C. R. G. thanks Spanish MEC for a research grant (FPU2014/00886). Authors acknowledge MINECO (ENE2016-74889-C4-2-R, AEI-FEDER-UE).

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THE ROLE OF FORMIC ACID/FORMATE EQUILBRIA IN THE OXIDATION OF FORMIC ACID ON PLATINUM ELECTRODES

C. Busó-Rogero*1,2, E. Herrero1, J.M. Feliu1

1Instituto de Electroquímica, Universidad de Alicante Apdo. 99 E-03080 Alicante

2IMDEA Nanociencia, c./ Faraday, 9 Ciudad Universitaria de Cantoblanco, E-28049 Madrid *e-mail: [email protected]

Keywords: Formic acid, platinum, single crystal electrodes, pH effect. Nowadays, formic acid oxidation reaction (FAOR) is widely studied as an alternative to hydrogen in the anode of fuel cells and as a simplified example of the oxidation of more complex organic molecules. The mechanism of FAOR on platinum electrodes is structure sensitive and the reactivity until the CO2 production is different depending on the Pt electrode [1]: via active intermediate (presumably formate [2]) for (111) surfaces and via CO formation in Pt (100) electrodes. Previous works have investigated the changes in the reactivity for pHs until 10 [3], showing an increasing activity when the amount of formate is incremented due to the acid-base equilibrium. However, there are no many studies about the FAOR at very low pHs. In this communication, formic acid oxidation has been studied in perchloric acid solutions until 9.14 M. Using the Pt (111) electrode as a surface which no contribution of poison formation is expected, it is observed a decrease in the activity at increasing concentrations of perchloric acid and reversible peaks in the voltammogram at high scan rates, assigned to the formate adsorption/desorption. In addition, new peaks appear in the hydrogen adsorption region, due to the interaction of perchlorate anions with water molecules, which can cause changes in their structure. Figure: Voltammetric profiles for: a) 0.01 M HCOOH at increasing concentrations of HClO4 and b) blank and 0.01 M HCOOH in 60% HClO4. Sweep rates: 0.05 Vs-1.

References [1] J.M. Feliu, E. Herrero, Formic acid oxidation, in: Wiley (Ed.) Handbook of Fuel Cells, 2010. [2] M. Osawa, K. Komatsu, G. Samjeske, T. Uchida, T. Ikeshoji, A. Cuesta, C. Gutierrez, Angew. Chem.-Int. Edit. 50 (2011) 1159. [3] J.V. Perales-Rondón, S. Brimaud, J. Solla-Gullón, E. Herrero, R. Jürgen Behm, J.M. Feliu, Electrochimica Acta 180 (2015) 479.

0,0 0,2 0,4 0,6 0,8 1,0-0,20,00,20,40,60,81,01,21,41,6

0.1 M HClO4

1 M HClO4

3 M HClO4

5 M HClO4

9.14 M HClO4

j/mA

cm-2

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a)

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0,2 0.01 M HCOOH + 9.14 M HClO4

Blank 9.14 M HClO4

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E vs RHE/V

b)

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KINETIC IMPLICATIONS ON THE VOLTAMMETRIC RESPONSE OF A SURFACE EE MECHANISM

M. López-Tenés, J. González, C. Serna, A. Molina*

Departamento de Química Física, Facultad de Química, Regional Campus of International Excellence ‘‘Campus Mare Nostrum’’, Universidad de Murcia, 30100 Murcia, Spain


Keywords: EE mechanism, surface confined molecules, non-nernstian behaviour, voltammetry

Development of molecules possessing different redox states has attracted a great interest for their potential as electrocatalysts [1] or active units in charge-storage devices [2]. The situation in which the redox probes are confined at the electrode surface present additional importance since it offers different advantages such are a much lower amount of catalyst, the avoiding of crossover or bimolecular decomposition or deactivation routes, among others [2]. The application of the techniques PFV (Protein Film Voltammetry) and STM (Scanning Tunnelling Microscopy) has allowed the characterization of the electron transfer (ET) mechanisms for a great number of molecules and biomolecules [3]. These molecules typically present electrode processes consisting of two-electron transfers (EE mechanism).

The evaluation and improvement of the performance of electrocatalysts goes through a detailed knowledge of the overall charge transfer mechanisms, i. e., through a complete characterisation of the ET events taking place between the electrode and these confined molecules, which includes the determination of the thermodynamic and kinetic stability of the different oxidation states in the molecule. A great number of interesting systems, including biomolecules and biomimetic inorganic complexes (polioxometallates or complex of iron or ruthenium), presents evidences of finite kinetics, a fact which compromises theoretical predictions when a Nernstian behaviour is assumed.

In this communication we present a theoretical description of surface reactions in which an immobilized molecule reduces in two steps, considering the kinetic of both interfacial ETs [4, 5]. The solution presented, due to its discrete nature, is applicable to any multipotential step technique and it also allows to obtain the continuous limit of Cyclic Voltammetry for which only numerical calculations had been used previously. The special features of the current-potential response for this situation are discussed with a special focus on the influence of the formal potentials and rate constants for the two ET steps.

References [1] Bullock, R. M.; Das, A. K.; Appel, A. A., Chem. Eur. J., 2017, 23, 7626. [2] Marchante, W.; Maglione, M. S.; Crivillers, N.; Rovira, C.; Mas-Torrent, M. RSC Adv., 2017, 7, 5636. [3] Fourmond, V.; Leger, C. Curr. Op. Electrochem. 2017, 1, 110. [4] Gonzalez, J., López-Tenés, M., Molina, A., J. Phys. Chem. C, 117 5208-5211, 2013. [5] López-Tenés, M.; Gonzalez, J.; Molina, A.; J. Phys. Chem. C, 118 12312-12324, 2014.

Acknowledgements: The authors greatly appreciate the financial support provided by the Fundación Séneca de la Región de Murcia (Project 19887/GERM/15) as well as by the Ministerio de Economía y Competitividad (Projects CTQ-2015-65243-P and CTQ-2015-71955-REDT Network of excellence “Sensors and Biosensors”).


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ELECTROCHEMICAL RESPONSES OF MONOLAYERS WITH INTERMOLECULAR INTERACTIONS. ANALYSIS OF THE CURRENT IN MULTIPOTENTIAL PULSE

CHRONOAMPEROMETRY AND SQUARE WAVE VOLTAMMETRY

Joaquín González*1, Jose Alfonso Sequí2

1Dpto. de Química Física, Facultad de Química, Universidad de Murcia, 30100 Espinardo, Murcia *e-mail: [email protected]

Keywords: Voltammetry, Electroactive monolayers, Intermolecular interactions

The interest and applications of redox molecular systems confined at conducting interfaces, and electroactive monolayers in particular, has grown remarkably in recent years [1]. In order to improve the performance of these devices it is necessary to get a detailed insight of the processes taking place and, with this aim, several theoretical models have been developed and tested with different electrochemical techniques, especially with Cyclic Voltammetry [2]. Unfortunately, in most practical situations, the experimental electrochemical responses deviate from the most used models based on an “ideal” behavior of the system. Non-idealities such as the presence of intermolecular interactions will cause a distortion of the electrochemical response of these systems [2, 3].

Here we present an extension of previous theoretical models corresponding to the current of electroactive monolayers by including the presence of intermolecular interactions. As the main novelties, we have considered the asymmetric Marcus-Hush kinetics formalism and the presence of electroinactive coadsorbates at the monolayer. The impact of such interactions on the kinetics of the charge transfer processes has been quantified through the analysis of the current-time and current-potential responses obtained upon the application multipotential pulse chronoamperometry [4, 5], and Square Wave Voltammetry [5].

In order to validate the theoretical results, the experimental analysis of the response of binary ferrocenylundecanethiol/decanethiol monolayers at gold and platinum electrodes at different coverages of the redox species has been carried out. The increase of the surface charge associated with ferrocene probes gives rise to a severe slowing down of the charge transfer process through a decrease of the apparent rate constant. References 1. J. Gooding, S. Ciampi, Chemical Society Reviews, 40 (2011) 22 2. J. J. Calvente, R. Andreu, Current Opinion in Electrochemistry, 1 (2017) 22-26 3. E. Laviron, Journal of Electroanalytical Chemistry 52 (1974) 395 4. J. Gonzalez, J. A. Sequi, ACS Omega 3(2018)1276-1292 5. A. Molina, J. González, Pulse Voltammetry in Physical Electrochemistry and Electroanalysis, Springer, 2016 Acknowledgments The authors greatly appreciate the financial support provided by the Fundación Séneca de la Región de Murcia (Project 19887/GERM/15) as well as by the Ministerio de Economía y Competitividad (Projects CTQ-2015-65243-P and CTQ-2015-71955-REDT Network of excellence “Sensors and Biosensors”).

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CITRATE ADSORPTION ON PLATINUM AND WHY IT SHAPES TETRAHEDRAL AND OCTAHEDRAL COLLOIDAL PLATINUM NANOPARTICLES

J. M. Gisbert-González*1, J. M. Feliu1, A. Ferre-Vilaplana2, E. Herrero 1

1Instituto de Electroquímica, Universidad de Alicante. Apdo. 99, E-03082 Alicante, Spain.

2Instituto Tecnológico de Informática, E-46022 Valencia, Spain, and Departamento de Sistemas Informáticos y Computación, EPS de Alcoy, Universidad Politécnica de Valencia. E-03801 Alcoy, Spain

*e-mail: [email protected] Keywords: platinum, citric acid, nanoparticles

Most of the electrochemistry reactions of interests such as those involved in the electrochemical energy conversion and storage in fuel cells and batteries are sensitive to the surface structure of catalyzers. For this reason, and searching for reactivity optimization, nanoparticles (NPs) have been widely used due to their catalytic properties which depend on both their shape and size. During the synthesis of NPs, adsorption of surfactant controls the shape by guiding the growing direction but, unfortunately, almost all of the synthesis processes are based on empirical results, ignoring how the surfactants act on them.

In the present study we have used a strategic combination of electrochemical experiments, spectroscopy and DFT calculation, on well defined-defined surfaces, to explain in detail the way in which a capping agent, citrate, determines the shape of colloidal platinum NPs.

Gibbs excesses and electrosorption valencies of citrate adsorbed on the Pt(111) electrode at different pH were determined, from the voltammetric profiles obtained under different citric acid concentrations, giving a maximum adlayer coverage of 0.2 (equivalent to 3·1014 molecules·cm-2). FTIR spectroscopy and DFT calculation give extra information about how the a bidental adsorption configuration guides to tetrahedral and octahedral colloidal platinum nanoparticles. Citrate adsorption on Pt(100) y Pt (110) analysis were carried out by qualitative comparison with other adsorbates.

0.0 0.2 0.4 0.6 0.8 1.0-120

-90

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-30

0

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60

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A · c

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E / V vs RHE

[Citric Acid] mM Blank 0.1 0.25 0.5 1.0 2.5 5.0 10.0

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ANALYTICAL EXPRESSIONS FOR THE STUDY OF FIRST-ORDER KINETIC CATALYTIC REACTIONS COUPLED TO A CHARGE TRANSFER VIA VISIBLE-UV

SPECTROELECTROCHEMISTRY

J.M. Gómez-Gil*, E. Laborda, A. Molina, F. Martínez-Ortiz

Departamento de Química Física, Facultad de Química, Campus Regional de Excelencia Internacional “Campus Mare Nostrum”, Universidad de Murcia, 30100, Murcia, España.

* [email protected]

Keywords: Catalytic mechanism; UV-visible spectroelectrochemistry; analytical theory; concentration profiles; reaction and diffusion layers.

The coupling of electrochemical and spectroscopic techniques has proven to be very useful to study non-interfacial phenomena of mass-transport [1] and homogeneous chemical reactions [2]. In this study, redox systems ascribed to a first-order kinetic catalytic mechanism are tackled via UV-visible spectroelectrochemical methods: 1

2

º'− →+ ←

E k

kO e R O

(1)

Explicit closed-form expressions are deduced for the concentration profiles and for the corresponding absortometric responses of the different species in both, normal- and parallel-beam configurations. With the theory presented, the suitability of both working modes is evaluated, discussing the optimum experimental conditions to determinate physicochemical parameters of interest (e.g.: chemical equilibrium and kinetic constants).

Figure 1. A) Parallel working arrangement with a coupled moving slit and B) comparison of the concentration profile (solid lines) and the corresponding normalized parallel-beam chronoabsortometric response (points) of species R under limiting current conditions (w = 10µm).

Also, the employment of a moving slit coupled to the light beam in parallel arrangement is considered (see Figure 1), achieving the reproduction of the evolution of the concentration profiles and thus, informing about the perturbed region due to the heterogeneous charge transfer, that is, about the reaction and diffusion layers. References [1] R. Pruiksma, R.L. McCreery, Anal. Chem. 51 (1979) 2253–2257. doi:10.1021/ac50049a045. [2] A. Molina, E. Laborda, J.M. Gómez-Gil, F. Martínez-Ortiz, R.G. Compton, J. Electroanal. Chem.

(2017). doi:10.1016/j.jelechem.2017.10.031. Acknowledgments Fundación Séneca (19887/GERM/15), Ministerio de Economía y Competitividad (CTQ-2015-65243-P), and Ministerio de Educación, Cultura y Deporte (Ayuda FPU-2015).

POSTER COMMUNICATIONS

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PAPER-BASED ELECTRODES MODIFIED WITH COBALT PHTHALOCYANINE FOR HYDROGEN PEROXIDE DETERMINATION

A. Sánchez Calvo, M.C. Blanco López, A. Costa García*

Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006 Oviedo, Spain.

[email protected]

Keywords: Paper-based, Cobalt phthalocyanine, Hydrogen peroxide Materials based on networks of cellulose fibers, such as paper, can be modified with carbon conductive inks to generate working electrodes with different applications [1]. As a step forward towards the development of competitive chemical sensors, these cellulose-based substrates can be additionally modified with nanomaterials, which provide them with different features: better conductivity, new electrodic surfaces, improved signal-to-noise ratio, or catalytic behavior. In this work, the paper cellulose was modified with Cobalt (II) phthalocyanine as a catalyst and it was applied to the determination of hydrogen peroxide. Paper-based carbon working electrodes (PCWEs) were made with chromatographic paper (Whatman Grade 1). Hydrophobic barriers were created by wax printing, to yield hydrophilic areas with a diameter of 4 mm. Then, 2 µL of a suspension of carbon ink (40% w/w in DMF) were added and dried at room temperature. The PCWE was overlaid at the surface of the working electrode of a screen-printed platform with an adhesive. A colloid of organometallic cobalt was prepared by solving Cobalt (II) phthalocyanine with hexadecyl trimethyl ammonium-bromide (CTAB). A protocol was followed to achieve smaller particle size and preconcentration by centrifugation [2]. 2 µL of Multi-walled carbon nanotubes were added to increase the conductivity of the cellulose system. Them, 2 µL of the colloidal solution were added on the upper side of the paper modified electrode. The determination of hydrogen peroxide was carried out by chronoamperometry by applying a potential of 0.4 V for 180 s. This nanocomposite electrode could be used for non-enzymatic determination of hydrogen peroxide, with a limit of detection of 50 µM. Future objectives are the optimization of the nanocomposite deposition and the development of enzymatic sensors. References [1] E. Nunez-Bajo, M.C. Blanco-Lopez, A. Costa-Garcia, M. T. Fernández-Abedul, Biosens. Bioelectron. 91 (2017) 824 [2] K. Wang, J. Xu, H. Chen, Biosens. Bioelectron. 20 (2005) 1338 Acknowledgements: This study was financed by the Consejería de Economía y Empleo del Principado de Asturias (Plan de Ciencia, Tecnología e Innovación 2013-2017), under the Grant GRUPIN14-021 and GRUPIN14-022 and the project CTQ2014-58826-R. Alberto Sánchez Calvo thanks the Ministry of Economy and Competitiveness for the award of a FPI Grant (BES-2015-072220)

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IODINE-MEDIATED MEASUREMENT OF RESVERATROL: AN ELECTROCHEMICAL STUDY

B. Gómez-Monedero*, M.I. González-Sánchez, R. Jiménez-Pérez, E. Valero

Department of Physical Chemistry, School of Industrial Engineers, University of Castilla-La Mancha,

Campus Universitario S/N, 02071 Albacete, Spain. *e-mail: [email protected]

Keywords: resveratrol, iodine, cyclic voltammetry, platinum electrodes

Resveratrol (3,4',5-trihydroxystilbene) is a phenol and phytoalexin that is naturally

produced by some plants as a response to injury [1]. This compound has been found to potentially present antioxidant and antimutagen properties, to mediate anti-inflammatory effects or to inhibit hydroperoxidase functions [2]. Due to the high value of this compound, great effort has been made to produce it in high amounts, such as the use of elicited suspension-cultured cells [3]. Therefore, it is very important to develop analytical methods that are able to measure this compound.

In the present communication, we report an electroanalytical methodology to measure this compound using cyclic voltammetry and platinum electrodes. The method involves the reaction of electro-generated iodine with resveratrol, which produces an increase in the current of the anodic peak from iodide oxidation and allows its easy analytical quantification. In addition, the behaviour of the electrochemical-chemical reaction system was studied. References [1] L. Fremont. Life Sciences 2000, 66 (8) 663-673. [2] M. Jang, L. Cai, G. O. Udeani, K. V. Slowing, C. F. Thomas, C. W. W. Beecher, H. H. S. Fong, N. R. Farnsworth, A. D. Kinghorn, R. G. Mehta, R. C. Moon, J. M. Pezzuto. Science 1997, 275 (5297) 218-220. [3] M. Chu, M.A. Pedreno, N. Alburquerque, L. Faize, L. Almagro. Plant Physiology and Biochemistry 2017, 113, 141-148. Acknowledgments Spanish Ministry of Economy and Competitiveness (MINECO, http://www.mineco.gob.es/portal/site/mineco/idi), Project No. BFU2016-75609-P (cofunded with FEDER funds, EU). B. G-M. is a post-doctoral research fellow of the Youth Employment Initiative (JCCM, Spain, cofounded with ESF funds, EU).

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ELECTROCHEMICAL QUANTIFICATION OF ORTHOPHENOLIC COMPOUNDS IN VIRGIN OLIVE OILS

A. Guiberteau-Cabanillas*1, L. Santillan-Marín, R. Pardo-Botello1, J. Sánchez2, M. Martínez-Cañas2

1 Department of Analytical Chemistry, Research Institute on Water, Climate Change and Sustainability (IACYS), University of Extremadura. Avda de Elvas s/n 06006 Badajoz, Spain,

2 Technological AgriFood Institute (INTAEX). Centre for Scientific Research and Technology in Extremadura (CICYTEX). Junta de Extremadura. Avda. Adolfo Suárez, s/n. E-06007 Badajoz, Spain

* email: [email protected]

Keywords: Differential pulse voltammetry, screen-printed electrode, dispersive liquid-liquid microextraction, orthophenols, virgin olive oils. A differential pulse voltammetry method (DPV) for the determination of the total content of orthophenolic compounds present in virgin olive oil (VOO) has been developed by using screen-printed carbon electrode, previous optimization of instrumental variables and chemical conditions. The developed method was applied to determine the phenols content in VOO (Figure 1) from different olives varieties and different agronomic practices related to irrigation management previous dispersive liquid-liquid microextraction (DLLME). VOO from Picual olives variety shows a higher orthophenolic compounds content, expressed as equivalent milligrams of hydroxytyrosol (HTY) per grams of VOO, compared to the other varieties, and increases in ripe dry Picual. An easy, speed and inexpensive method for VOO total orthophenols content quantification is proposed.

Figure 1. Voltammograms (DPV) of different VOO varieties and HYT alone.

Acknowledgements Financial support was provided by the Ministerio de Economía y Competitividad of Spain (Project CTQ2017-82496-P) and Junta of Extremadura (project GR15090 Research Group FQM003 and Project IB16058) cofinanced by the Fondo Europeo de Desarrollo Regional, and also Research Group AGA002.


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ELECTROCHEMICAL DETERMINATION OF MOXIFLOXACIN BY USING SCREEN PRINTED ELECTRODE

A. Guiberteau-Cabanillas*1, M. D. García Ponce, P. Ojalvo, R. Pardo-Botello1

1Department of Analytical Chemistry, Research Institute on Water, Climate Change and Sustainability

(IACYS), University of Extremadura. Avda de Elvas s/n 06006 Badajoz, Spain, * email: [email protected]

Keywords: Moxifloxacin, differential pulse voltammetry, screen-printed carbon electrode, spectrophotometry.

Moxifloxacin is a fourth-generation quinolone antibiotic used in the treatment of eyes and respiratory tract infections. This antibiotic exhibits a voltammetric oxidation response (DPV and CV) on screen printed electrodes (SPE). For that, a voltammetric method has been developed for the determination of moxifloxacin in pharmaceutical preparations (eye drops) and in urine samples without any pre-treatment. The influence of pH on the Ip and Ep (DPV) showed the participation of protons on the electrodic process (pH >5), being this process irreversible and controlled by diffusion (CV). The figure of merits has been calculated, showing a linear relationship between the Ip and the concentration of moxifloxacin in the range 1.4 to 8.4 mg/L. The detection limits calculated by the Winefordner-Long [1] and Clayton [2] methods were 0.4175 mg/L and 0.6964 mg/L respectively, being the quantification limit of 1.377 mg/L. The results obtained of the developed voltammetric method in urine and eye drops was validated by a spectrophotometric method, obtaining recovery values with respect to the nominal values indicated in the preparation pharmaceutical of 98-109% and 95-96% by DPV and spectrophotometry method respectively. In human spiked urine samples the recovery values were 82- 85% by DPV and 98-132% by spectrophotometric methods. The results obtained by DPV are in accordance with those obtained using spectrophotometric alternative methods and, therefore, the DPV method is very suitable for routine determination of Moxifloxacin. References [1] Long, G. L., & Winefordner, J. D. (1983). Limit of Detection: A Closer Look at the IUPAC Definition. Analytical Chemistry, 55(7), 712A–724A. https://doi.org/10.1021/ac00258a001 [3] Clayton, C. A., Hines, J. W., & Elkins, P. D. (1987). Detection Limits with Specified Assurance Probabilities. Analytical Chemistry, 59(20), 2506–2514. https://doi.org/10.1021/ac00147a014

Acknowledgements Financial support was provided by the Ministerio de Economía y Competitividad of Spain (Project CTQ2017-82496-P) and Junta of Extremadura (project GR15090 Research Group FQM003 and Project IB16058 by the European FERDER funds for financially supporting this research.


https://doi.org/10.1021/ac00147a014

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SPECIATION AND AVAILABILITY OF INDIUM(III) THROUGH ELECTROANALYTICAL TECHNIQUES

J. Galceran*, M. H. Tehrani, A. Dago, E. Companys and J. Puy

Dep. Chemistry, Universitat de Lleida & AGROTECNIO, Av. Rovira Roure 191, 25198 Lleida, Spain

*e-mail: [email protected] Keywords: AGNES, electroanalysis, Indium, lability degree Significant health and environmental concerns could appear as a result of indium’s leakage from many electronic devices into the environment. Almost no investigation has been focused on determining directly the free concentration of In(III). This knowledge might be useful to check hegemonic ecotoxicological paradigms which ascribe a key role to the free metal ion concentration. As indium is an amalgamating element with a negative standard redox potential, it can be tackled with AGNES (Absence of Gradients and Nernstian Equilibrium Stripping) [1], an electroanalytical technique designed to determine free metal ion concentration in solutions. AGNES has been successfully applied to Zn, Cd, Pb and Sn in a variety of systems such as seawaters, river waters, dispersions of nanoparticles, extracts of soils, etc. (see recent review [2]). The deposition stage in AGNES lasts until a special situation of equilibrium is reached, when the ratio (called gain) between the concentration in the amalgam and the free ion concentration in the solution is ruled by Nernst equation. The (short term) irreversibility of Indium prevents a direct computation of the gains from a Differential Pulse Polarogram, so a new calibration procedure has been devised [3]. Speciation results with AGNES in the systems Indium+Nitrilotriacetic acid and Indium-Oxalate [4] indicate that the stability constants in NIST 46.7 could be improved with more modern determinations. A new strategy, called Accumulation under Diffusion Limited Conditions (ADLC), can be applied to compute the lability degree of complexes. The lability degree is linked to the availability of this element as it describes the contribution of the complexes to the overall uptake flux. The use of highly labile complexes allows for a dramatic reduction of the deposition times. Picomolar concentrations of free indium in solutions with precipitated In(OH)3 at pH 6 have been determined. References: 1. Galceran, J., et al., AGNES: a new electroanalytical technique for measuring free metal ion concentration.

Journal of Electroanalytical Chemistry, 2004. 566(1): p. 95-109. 2. Companys, E., et al., A review on electrochemical methods for trace metal speciation in environmental media.

Current Opinion in Electrochemistry, 2017. 3(1): p. 144-162. 3. Tehrani, M.H., et al., Free indium concentration determined with AGNES. Science of the Total Environment,

2018. 612: p. 269-275. 4. Pingarron, J.M., R. Gallego-Andreu, and P. Sanchez-Batanero, Potentiometric determination of stability

constants of complexes formed by indium(III) and different chelating agents. Bulletin de la Societé Chimique Française, 1984: p. 115-122.

Acknowledgments: Funding from the Spanish Ministerio de Economía, Industria y Competitividad (CTM2016-78798) is acknowledged.

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BIOSENSORS ON SCREEN-PRINTED ELECTRODES FOR IMIDACLOPRID DETERMINATION

B. Pérez Fernández, A. Costa García*

Department of Physical and Analytical Chemistry, University of Oviedo, Julian Clavería 8, 33006

Oviedo, Asturias (Spain) *e-mail: [email protected]

Keywords: Biosensor, Immunosensor, Imidacloprid, Screen-Printed Carbon Electrodes. Insecticides, such as Imidacloprid (IMD), are worldwide used for pest control. This pesticide is a derivate of nicotine, with neuroactive properties. Its determination is very important because it has a prolonged residual effect on the soil, due to its high solubility in water. In addition, in surface water it is degraded in a series of toxic compounds for vertebrates, mammals and humans, due to the action atmospheric parameters such as sunlight, pH, temperature, etc. In this work, two types of immunosensors on Screen-Printed Carbon Electrodes (SPCE) are proposed, one through a direct assay and another with an indirect configuration. The direct assay (Fig. 1A) is carried out by immobilization of a monoclonal antibody (mAb-IMD) over the working electrode (previously nanostructured with/without gold nanoparticles (AuNP)). In a second step, the labelled antigen (IMD-HRP) is added and incubated. In the other configuration, the indirect assay (Fig. 1B), over the working electrode (with or without AuNP) the antigen (BSA-IMD) is immobilized, and then the mAb-IMD is added, and finally a labelled polyclonal antibody (anti mouse IgG-HRP) is incubated. For both configurations, the determination of IMD is through a competitive immunoassay [1][2].

Fig.1. Scheme of the immunoassay: A) Indirect assay; B) Direct assay. References: [1] G. Martínez-Paredes, M.B. González-García, A. Costa-García, In situ electrochemical generation of gold nanostructured screen-printed carbon electrodes. Application to the detection of lead underpotential deposition, Electrochim. Acta 54 (2009) 4801–4808 [2] Hee-Joo Kim, Weilin L. Shelver, Qing X. Li, Monoclonal antibody-based enzyme-linked immunosorbent assay for the insecticide imidacloprid. Analytica Chimica Acta., 509 (2004) 111-118

Acknowledgments: This work has been supported by the FC-15-GRUPIN-021 project from the Asturias Regional Goverment and the MINECO-15-CTQ2014-58826-R project from the Spanish Ministry Economy and Competitiveness (MINECO).


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ELECTROCHEMICAL SIGNAL PERFORMANCE ENHANCED OF THE ELECTROOXIDATION OF H202 USING SPCE/POLYMER/METAL NANOPARTICLES

MODIFIED ELECTRODE

R. Jimenez-Pérez1, I. González-Sánchez1, B. Gómez-Monedero1, J. Agrisuelas2 y E. Valero1

1Department of Physical Chemistry, Superior Technical School of Industrial Engineering, University of Castilla-La Mancha, Campus Universitario s/n, 02071, Albacete, Spain.

2Department of Physical Chemistry, Faculty of Chemistry, University of Valencia, C/ Dr. Moliner 50, 46100 Burjassot, Valencia, Spain.

Keywords: Chronoamperometry, H2O2, Metal Nanoparticles, Electrochemical sensor, Modified electrode. The determination of hydrogen peroxide (H2O2) has played an important role in biomedical, environmental, and industrial analyses. Many detection techniques have been developed among which could be highlighted the electrochemical protocol since it has been widely applied for accurate determination of H2O2 for its high sensitivity, low detection limit and low cost. The use of carbon-based screen-printed electrodes (SPCEs) for the detection of H2O2 has been previously studied by our research group demonstrating their usability as portable sensors for different applications [1]. Conducting polymers (CPs) have shown high efficiency for electrocatalytic applications given their special characteristics, such as cost-effectiveness, facile synthesis, stability, reproducibility and good sensitivity. During this process, the polymeric structure and doping agents in CPs are fixed, which confer their special characteristics [2]. This work presents the development of different electrodes obtained on different carbon surfaces following a similar sequential pattern: 1) Activation of the carbon surface, 2) Polymerization on the previously activated surface 3) Surface modification of Polymer/SPCEs with metallic nanoparticles generated electrochemically in situ. The obtained electrodes show an increase in the electrochemical signal towards H2O2. The electrocatalytic efficiency of the manufactured electrode is highlighted in real samples. The electrochemical signal in electrodes thus achieved improves at least 20% the signal obtained in previous methods and allows us to lower the detection limit also. [1] J. Agrisuelas, M.I. González-Sanchez, B. Gómez-Monedero and E. Valero. Polymers, 10, 48 (2018). [2] J. Agrisuelas, M.I. González-Sánchez and E. Valero. Journal of the Electrochemical Society, 164 (2) G1-G9 (2017). This work was supported by the Spanish Ministry of Economy and Competitiveness [Grant No. BFU2016-75609-P] (cofounded with FEDER funds, EU). BGM is a post-doctoral research fellow of the Youth Employment Initiative (JCCM, Spain, cofounded with ESF funds, EU).

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ASIMMETRIC MODIFICATION OF ZnO NANOSTRUCTURES BY SIMULTANEOUS APPLICATION OF BIPOLAR ELECTROCHEMISTRY AND UV LIGHT

M. Briones*1, S. Catalán-Gómez2, J.L. Pau2, A. Kuhn3, E. Lorenzo4

1Departamento de Química Analítica y Análisis Instrumental. Facultad de Ciencias,2Departamento de

Física Aplicada. Facultad de Ciencias, 3CNRS-ENSCBP. Univ. Bordeaux, 33607 Pessac (France),4Instituto Madrileño de Estudios Avanzados (IMDEA) -Nanoscience. Faraday 9, 1,2,4 Campus

de Excelencia de la Universidad Autónoma de Madrid. 28049 Madrid. Spain. *e-mail: [email protected]

Keywords: bipolar electrochemistry, ZnO. Bipolar electrochemistry is a technique based in the polarization of a conductive material into an electric field that generates different reactivity in the surface of both sides of the object (Janus particles). This polarization is proportional to the electric field and the dimension of the object. For small objects, we need to apply strong electric field, but it is reported that, if we apply UV light and electric field simultaneously, we can avoid this technical limitation [1]. When a conductor/semiconductor object absorbs light with an energy greater than its band gap, electron-hole pairs (e--h+) are generated. Then, e- and h+ are migrating to the surface of the object and redox reactions can be carried out in the presence of active redox species. If a strong electric field is applied simultaneously, it leads to a polarization in the sides of the semiconductor object, which facilitates the separation of the e- and h+ to opposite sides of the particle, where the reduction and oxidation reactions occur [2]. This method was applied for the asymmetric modification of ZnO nanowires with a metal deposit of gold. After the optimization of the main parameters, best results were obtained applying an external electric field of 1KV and 50% of UV light intensity during 180s to a 0.005% ZnO suspension in EtOH/H2O containing 1mM HAuCl4. Under these conditions, some difference in the metal deposit on both sides of the nanostructure can be observed as it is shown in the SEM micrographs.

References [1] Ongaro et al., ChemElectroChem. 2014, 1, 2048 – 2051 [2] S. Tiewcharoen et al., Angew. Chem. 2017, 129, 1–6 Acknowledgments: This work has been supported by Ministerio de Economía, Industria y Competitividad (Project no. CTQ2014-53334-C2-1-R)

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CARBON DOTS MODIFIED ELECTRODES FOR CATALYSIS OF HYDRAZINE

M. Mediavilla1,3, M. Revenga-Parra1,2,3, I. Bravo1,3, F. Pariente1,2,3 and E. Lorenzo*1,2,3

1 Departamento de Química Analítica y Análisis Instrumental, 2 Institute for Advanced Research in Chemical Sciences (IAdChem), Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain,

3 Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Campus UAM, Cantoblanco, 28049 Madrid, Spain

*e-mail: [email protected] Keywords: Carbon nanodots, hydrazine oxidation, electrocatalyst. Electrocatalysis plays a key role in increasing efficiency of the interesting analytes such as hydrazine, and as a result, efforts have been made by the researchers to develop new materials easy to prepare and at low cost capable of reducing the hydrazine oxidation overpotential. In this context, a new nanomaterial of the carbon family, carbon nanodots with carboxylic surface groups (CDCOOH) have herein been fabricated and employed to modify screen-printed gold electrodes (AuSPEs). The resulting modified electrodes exhibit excellent electrocatalytic activity towards the oxidation of hydrazine. CDCOOH allow for a facile electrode modification. The oxidation of hydrazine takes place at 0.02 V. Therefore, modification of the electrode with carbon nanodots reduced the overpotential of hydrazine oxidation in 140 mV compared to bare AuSPE. The catalytic rate constant (kcat) and the diffusion coefficient (D) was estimated by chronoamperometry and they were found to be 5.10x106M-1s-1 and 8.42x10-6cm2s-1, respectively. The CDCOOH also exhibited excellent long-term stability, is very useful as hydrazine electrochemical sensor. The developed sensor responses linearly to hydrazine in the range of 1.0 to 100 µM with a detection limit of 0.8 µM. Acknowledgments Authors acknowledge funding from Comunidad de Madrid (NANOAVANSENS Program S2013/MIT-3029) and Ministerio de Economía y Competitividad (CTQ2014-53334-C2-1-R).

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SPECTROELECTROCHEMISTRY AND ELECTROGRAVIMETRY OF PRUSSIAN BLUE FILMS IN PRESENCE OF CESIUM

A.F. Roig1, J. Agrisuelas2, J.J. García-Jareño2, S. Lozano2, A. San Matías2, F. Vicente2

1 Research Institute for Pesticides and Water, Universitat Jaume I, E-12071, Castellón, Spain

2 Departament de Química Física. Facultat de Química. Universitat de València. C/ Dr Moliner 50 46100 Burjassot (València)

*e-mail: [email protected] Keywords: spectroelectrochemistry, electrogravimetry, Prussian Blue, cesium

In previous works Prussian Blue films was voltammetric cycled or only immersed in CsCl aqueous solutions observing an increase in the motional resistances Rm of about 300 ohm. Simultaneously, a decrease in the resonance frequency is also recorded, suggesting a spontaneous insertion of Cs into the films. Then, two different types of cesium exchange are postulated: one associated to the electrochemical reaction during the first scan, and another spontaneous non-stoichiometric entrance where the Cs is located inside the inner water cluster. This means that a part of the water molecules are expelled from the cluster and consequently the film losses electrical conductance as well as their mechanical rigidity increases. It is proposed that the Cs is retained into the interstitial water cluster placed between the framework formed by means Fe(II)low spin-CN-Fe(III)high spin structural units. Then, there are two different ways for entering the cesium to the structural zeolite-building of Prussian Blue: CsCl enters chemically by and spontaneous substitution of inner water molecules of the interstitial water cluster and, also its could enters as counter-ion Cs+ during the first reduction scan of the electrochemical stabilization process of the PB [1,2]. This work is focused to study in depth the insertion of cesium into the structure of Prussian Blue by means ac-electrogravimetry because this a good tool for understand the use of this material to remove radioactive cesium from contaminated water in nuclear disasters and for treatment of radiocesium poisoning [3].

References [1] J.J. Garcia-Jareno, D. Gimenez-Romero, F. Vicente, C. Gabrielli, M. Keddam, H. Perrot, EIS and Ac-

electrogravimetry study of PB films in KCl, NaCl, and CsCl aqueous solutions, J. Phys. Chem. B. 107 (2003) 11321–11330.

[2] J.J. Garcia-Jareno, J. Navarro-Laboulais, A. Sanmatias, F. Vicente, The correlation between electrochemical impedance spectra and voltammograms of PB films in aqueous NH4Cl and CsCl, Electrochimica Acta. 43 (1998) 1045–1052.

[3] D.F. Thompson, C.O. Church, Prussian blue for treatment of radiocesium poisoning, Pharmacotherapy. 21 (2001) 1364–1367.



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STUDY OF THE CATALYTIC ACTIVITY OF CERIUM OXIDE NANOPARTICLES

A. Iglesias-Mayor1, L. Fernández-Murillo2, F. J García-Alonso2, A. Costa-García*1

1 Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006 Oviedo, España, 2 Departamento de Química Orgánica e Inorgánica, Facultad de Química, Universidad

de Oviedo, 33006 Oviedo, España *e-mail: [email protected]

Keywords: cerium oxide; nanoparticles; catalytic activity; electrochemistry Cerium oxide nanoparticles (CeO2 NPs) also known as ceria nanoparticles or nanoceria can be distinguished from other metal oxides by its dual valence state (Ce3+, Ce4+) and by the oxygen vacancies existent in its structure [1]. Its characteristics, high oxygen storage and ease of transition between trivalent and tetravalent states, coupled with its fluorite crystalline structure play a critical role in the catalytic and redox activity of nanoceria, allowing them to take part in redox reactions both as an oxidizing and a reducing agent [2]. In this work poly (acrylic acid)-coated nanoceria were synthesized according to the literature [3]. After that, PAA-CeO2 NPs were adsorbed on the working electrode surface of Screen- Printed Carbon Electrodes (SPCE) and the electrochemical behaviour of electroactive species, such as ferrocyanide and ferricyanide, in different mediums was studied by cyclic voltammetry. And it has been found that both in acid or neutral conditions, totally different voltammograms were observed for the bare electrode and for the PAA-CeO2 NPs-modified electrode (Fig.1), which means that nanoceria have a catalytic effect in these conditions. -30 -20 -100 10 20-0.50 0.00 0.50 1.00 Current

Fig. 1. CVs for bare SPCE (black) and PAA-CeO2 NPs-modified SPCE (green) of 0.001 M solutions of potassium ferrocyanide in HCl 0.1 M (left)/NaCl 0.1 M (right)

References [1] D. Andrescu, G. Bulbul, R.Özel et al., Environ. Sci.: Nano, 1 (2014), 445-458 [2] F. Charbgoo, M. Ramezani, M. Darroudi, Bios. Bioelectron., 96 (2017), 33-43 [3] Y. Sun, C. Zhao, N. Gao et al., Chem. Eur. J., 23 (2017), 1-6

Acknowledgments This work has been supported by the FC-15-GRUPIN14-021 project from the Asturias Regional Government and the CTQ2014-58826-R project from the Spanish Ministry of Economy and Competitiveness (MINECO). A. Iglesias-Mayor thanks the Spanish Ministry of Education, Culture and Sports (MECD) for the award of a FPU Grant (FPU2014/04686).


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COMPETITIVE ELECTROCHEMICAL IMMUNOSENSOR FOR THE DETECTION OF UNFOLDED P53 BASED ON SCREEN-PRINTED CARBON ELECTRODES

O. Amor-Gutiérrez, E. Costa Rama, A. Costa-García*

Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo,

33006 Oviedo, Spain *e-mail: [email protected]

Keywords: Alzheimer’s Disease, Alzheimer, immunosensor, biosensor, p53 Nowadays, almost 47 million people in the whole world, most of them older than 60 years old, live with dementia, and this number is expected to increase to over 131 million people by 2050 [1]. Alzheimer’s disease (AD) is the most common neurodegenerative disorder, that is characterized by causing irreversible cognitive and physical deterioration. Because of this, the study of AD and the biomarkers associated with this condition is increasingly important. In the last years, it has been demonstrated that protein p53 is involved in neurodegenerative processes: different immunoprecipitation studies discriminated a different p53 tertiary structure in fibroblasts from control elderly subjects in comparison to that found in fibroblasts from AD patients. In addition, it can be also defined as a predictive biomarker of the transition from mild cognitive impairment (in where patients have cognitive deficits but not sufficient to distinguish any specific dementia) to Alzheimer’s Disease [2]. In this work, we describe an electrochemical immunosensor based on Screen-Printed Carbon Electrodes (SPCEs) for the detection of unfolded p53. It consists of a competitive immunoassay on a gold nanostructured SPCE. The label used is alkaline phosphatase (S-AP) and a mixture of 3-indoxyl phosphate with silver ions (3-IP/Ag+) is used as substrate. Analytical signal is based on the oxidation of the enzymatically generated silver, as previously done in our research group [3]. A scheme of the different steps of the biosensor can be seen in Figure 1. With this design, different optimizations (concentration of antibody, labelled peptide or bovine serum albumin for the blocking step) have been done.

Figure 1. Scheme of the different steps of the biosensor for unfolded p53

References [1] M. Prince et al., Alzheimer’s Disease International (ADI), 2016, London, UK. [2] C. Lanni et al., J. Alzheimers Dis. 20 (2010) 97-104. [3] E. Costa Rama et al., Sens. Actuators B. 201 (2014) 567-571.

Acknowledgments This work has been supported by the FC-15-GRUPIN14-021 project from the Asturias Regional Government and the CTQ2014-58826-R project from the Spanish Ministry of Economy and Competitiveness (MINECO).

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ELECTRONIC TONGUE SYSTEM-FOR THE RESOLUTION OF A TERNARY MIXTURE OF BENZODIAZEPINES

Farzad Torabi1,2, Andreu González-Calabuig1, Manel del Valle*1

1 Sensors and Biosensors Group, Department of Chemistry, Universitat Autònoma de Barcelona,

Edifici Cn, 08193 Bellaterra, Barcelona, Spain, 2Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran

*e-mail: [email protected] Keywords: 1,4-benzodiazepines, voltammetry, electronic tongue, artificial neural networks Benzodiazepines (BNZs) are commonly used psychotropic drugs used in a wide range of medical applications such as aesthetic and palliative treatments [1]. Apart, the psychotropic sedative effects and memory loss exhibited by BNZs has led to be increasingly reported in sexual assaults or robberies, where the victim is rendered unable to resist the attacker and has an incomplete recall of the attack, making their analysis of interest in the forensics field. Particularly, the required dose of these drugs to observe its effects is very low [2]. Another aspect of interest resides in the fact that once these pharmaceuticals reach the environment, they are considered contaminants of emerging concern [3]. As regards the above reasons, sensitive methods capable of determining these compounds in different complex media are required to quantify and identify these drugs in different fields. In the proposed approach, we take advantage of the electroanalytical properties of BNZs [3], to develop an electronic tongue analysis system formed by an array of voltammetric sensors plus complex data treatment methods consisting in extraction of significant information and obtaining a multicomponent response model. The methodology has been applied in the identification and simultaneous determination of ternary mixtures of BNZ products (Diazepam, Lorazepam and Flunitrazepam) in complex matrices. The six voltammetric sensors used were made of graphite epoxy composite (GEC) base material plus different modifiers from available nano components; their choice is justified by the proper differentiation obtained when their sensitivity against the different species is inspected by principal component analysis (PCA). Cyclic voltammetry signals obtained were compressed using Discrete Wavelet transform prior to data handling by chemometric tools; among these, artificial neural networks (ANNs) were employed to build the quantitative prediction model. In this manner, a set of standards based on a modified full factorial design was prepared to build the model; afterwards, this was validated with an external test set. Finally, the model successfully predicted the concentration of the three considered BNZs. References [1] C.Nogueira Nunes, V. Egéa dos Anjos, S. Pércio Quináia, Electroanalysis, 2018. 30(1), 109. [2] K.C. Honeychurch, G. M. Davidson, E. Brown, J. P. Hart, Anal. Chim. Acta, 853 (2015 222. [3] W.F.Smyth, A.Ivaska, Analyst 110 (1985) 1377 [4] R. Moreno-González, S.Rodriguez-Mozaz, M.Gros, D.Barceló, V.León, Environ Res. 138 (2015) 326.


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CHARACTERIZATION OF A POLYMER BRUSHES-INITIATOR MODIFIED SURFACE BUILT ON GOLD ELECTRODES

I. Humanes*, G. Sánchez-Obrero, R. Madueño, M. Blázquez and T. Pineda

Departamento Química Física y Termodinámica Aplicada, Instituto de Química Fina y Nanoquímica, Universidad de Córdoba, Ed. Marie Curie, 2ª Planta, Campus de Rabanales, 14014 Córdoba, España.

e-mail: [email protected] Keywords: polymer brush, self-assembled monolayer, “grafting from”, gold electrode. The protection of metal surfaces from fouling and corrosion can be made by grafting polymers of different size and chemical nature. One of the most interesting polymer-based modifications are these composed of polymer brushes. These consist of chain-end tethered polymers densely grafted on a surface. The way to prepare these nanostructured materials can be made by two methods: “grafting onto”, that uses appropriately chain-end functional polymers that are subsequently attached to a surface that presents complementary reactive groups or, “grafting from”, that consists of the polymerization of the monomer of interest from a surface that is modified with an appropriate initiator or chain transfer agent [1]. In this work, we attempt to build a film of polymer brushes on a gold surface by using the “grafting from” approach. To start with, a self-assembled monolayer (SAM) of 9-mercapto-1-nonanol (MNOH) has been built on a gold surface. The second step involves the modification of the -OH terminal groups with α-Bromoisobutyryl bromide (BIBB) in the presence of Triethylamine, to get the initiator-modified surface [2]. We have characterized the layers formed upon these two steps by using electrochemical techniques such us cyclic voltammetry and electrochemical impedance spectroscopy and infrared-reflection-absorption and X-ray photoelectron spectroscopies, as well as, by contact angle measurements. The aim of this work is to stablish the experimental conditions to obtain a modified surface with optimal properties to graft the polymer brushes in a densely packed film. Moreover, the problem of polymer detachment when in contact to the biological medium is addressed by studying the strength of the modified surface. References. [1] H.-A. Klok, J. Genzer, Expanding the Polymer Mechanochemistry Toolbox through Surface-Initiated Polymerization, ACS Macro Lett., 4 (2015) 636-639. [2] J.E. Friis, K. Brøns, Z. Salmi, K. Shimizu, G. Subbiahdoss, A.H. Holm, O. Santos, S.U. Pedersen, R.L. Meyer, K. Daasbjerg, J. Iruthayaraj, Hydrophilic Polymer Brush Layers on Stainless Steel Using Multilayered ATRP Initiator Layer, ACS Appl. Mater. Interfaces, 8 (2016) 30616-30627. Acknowledgments. Ministerio de Economía y Competitividad (MINECO) (Proyectos CTQ2014-60227-R and CTQ-2015-71955-REDT Red de Excelencia Sensores y Biosensores Electroquímicos), Junta de Andalucía (P10-FQM-6408) y Universidad de Córdoba.


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AN ELECTROCHEMICAL QUARTZ CRYSTAL MICROBALANCE (EQCM) STUDY OF OLIGOETHYLENEGLYCOL SELF-ASSEMBLED MONOLAYERS (OEG-SAMS) ON

GOLD SUBSTRATES

M. Chávez-Peraza*, G. Sánchez-Obrero, R. Madueño, M. Blázquez, T. Pineda


e-mail: [email protected] Keywords: OEG-SAM, nanomaterials, Bionanomedicine, EQCM The use of adsorbed oligoethyleneglycol (OEG) films on different surfaces has become an important strategy to prepare biocompatible materials. This is because its antifouling properties, in particular, the protection against unspecific adsorption of proteins. With the recent increase of the interest in the application of nanomaterials in Bionanomedicine, this type of protection has turn out to be of a major relevance [1]. In this sense, the knowledge of the organization of the OEG chains in the adsorbed films as well as the final structure that confers the antifouling properties is of a great interest, in particular, when high molecular weight polymers are used. We have previously studied some aspects on the organization degree within the layers formed with OEG of different molecular weight (from 800 to 6000 g/mol) on gold substrates that have been asserted by using cyclic voltammetry and electrochemical impedance spectroscopy. Emphasis has been focused on the ability of the molecular layers to block the access of ions or molecules from solution. In the present study, we complement the OEG-SAMs characterization employing electrochemical quartz crystal microbalance (EQCM) measurements [2]. By using this technique, mass changes taking place at the solution-surface interface can be sensitively followed. We can distinguish two different mass-change caused by the reductive desorption of ex-situ formed SAMs and by the ion transport within the well-formed layer. Moreover, we have evaluated the molecular organization by using FT-IRRAS, XPS spectroscopy and Contact Angle measurements. References. [1] G.G. Hedir, M.C. Arno, M. Langlais, J.T. Husband, R.K. O'Reilly, A.P. Dove, Poly(oligo(ethylene glycol) vinyl acetate)s: A Versatile Class of Thermoresponsive and Biocompatible Polymers, Angew. Chem. Int. Ed. , 56 (2017) 9178-9182. [2] K. Sadman, Q. Wang, S.H. Chen, D.E. Delgado, K.R. Shull, pH-Controlled Electrochemical Deposition of Polyelectrolyte Complex Films, Langmuir, 33 (2017) 1834-1844. Acknowledgments. Ministerio de Economía y Competitividad (MINECO) (Proyectos CTQ2014-60227-R and CTQ-2015-71955-REDT Red de Excelencia Sensores y Biosensores Electroquímicos), Junta de Andalucía (P10-FQM-6408) y Universidad de Córdoba.


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111

MONITORING THE PASIVATION REACTIONS IN Na-O2 BATTERIES BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY

I. Landa-Medrano1, I. Ruiz de Larramendi*1, J.T. Frith2, I. Lozano1, N. García-Araez2, T. Rojo1,3

1 Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco

(UPV/EHU) Barrio Sarriena s/n, 48940 Leioa-Spain, 2 Department of Chemistry, University of Southampton, SO17 1BJ, Southampton-UK, 3 CIC EnergiGUNE, Albert Einstein 48, 0150, Miñano-Spain

*e-mail: [email protected] Keywords: sodium-oxygen battery, electrochemical impedance spectroscopy Rechargeable metal-oxygen batteries have emerged as a possible alternative to lithium ion batteries due to their potential to provide high energy density [1]. So far almost all the efforts in this field have been focused towards lithium-oxygen (Li-O2) batteries. Nevertheless, due to the high overpotentials, low Coulombic efficiency and poor cycling performance of these batteries, in the last years the investigation has been intensified in the development of sodium-oxygen (Na-O2) batteries. These systems present lower OER overpotentials and cleaner cell chemistries, but a sudden death behavior is observed during both discharge and charge, resulting in a dramatic increase in cell potential near the end of charge. New methods have to be developed for understanding the mechanisms that take place in these devices in order to optimize their performance. In this work, a discharge product accumulation, elimination and passivation model for Na-O2 batteries was developed based on galvanostatic and electrochemical impedance spectroscopy (EIS) measurements using a 3-electrode cell [2]. Anode and cathode processes were distinguished and the accumulation of discharge products in the oxygen electrode was monitored. Discharge product deposition and removal was demonstrated to be a solution-process for the NaO2 nuclei formed in the initial stages of the discharge. As the ORR continues, however, the oxygen electrode becomes covered by smaller nuclei that lead both the ORR and the OER to become surface-processes. Evidence of formation of passivating products was also found. References [1] I. Landa-Medrano, C. Li, N. Ortiz-Vitoriano, I. Ruiz de Larramendi, J. Carrasco, T. Rojo, Sodium-Oxygen Battery: Steps Toward Reality, J. Phys. Chem. Lett. 7 (2016) 1161–1166. [2] I. Landa-Medrano, J.T. Firth, I. Ruiz de Larramendi, I. Lozano, N. Ortiz-Vitoriano, N. Garcia-Araez, T. Rojo, J. Power Sources, 345 (2017) 237-246. Acknowledgments This work has been partially supported by the "Ministerio de Economía y Competitividad" of Spain (under project MAT2016-78266-P), the FEDER and the Eusko Jaurlaritza/Gobierno Vasco (under projects IT-570-13 and ELKARTEK CICE17). I.L.M. thanks the UPV/EHU for his postdoctoral fellowship. NGA gratefully acknowledges EPSRC for an early career fellowship (EP/N024303/1). Financial support from EPSRC through the Energy SUPERSTORE call "supporting early career researchers" is also gratefully acknowledged (EP/L019469/1).

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SYNTHESIS AND CHARACTERIZATION OF MULTIDIMENSIONAL REDOX ACTIVE

COORDINATION POLYMERS

J. Montero1,2, Daniel Arenas3, David Ávila-Brande3, Elizabeth Castillo-Martínez4, S. Licoccia2, J. Carretero-González*1

1Institute of Polymer Science and Technology, ICTP-CSIC, Madrid, Spain

2Department of Chemical Science and Technologies, University of Tor Vergata, Rome, Italy 3Universidad Complutense de Madrid, Madrid, Spain

4 University of Cambridge, Department of Chemistry, Cambridge, United Kingdom *e-mail: [email protected]

Keywords: coordination polymers, electrochemical properties, cyclic voltamperometry

Coordination polymers (CPs) have attacked interest in recent years due to their properties such as gas adsorption, drug delivery, catalysis and ionic conductivity. CPs have advantages of a highly ordered and porous structure and a wide design latitude of compounds by choosing various metal ions and bridging ligands. On this work we synthesized a series of CPs containing chloranilic acid (A) and pyrazine (B) linkers with first raw transitions metals. The structure of these compounds was determined by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), IR spectroscopy (IR) and elemental analysis. Finally, their electrochemical properties were evaluated by cyclic voltamperometry and galvanostatic methods.

References: [1] Richard Robson et al. J. Chem. Soc., Dalton Trans. (2000) 1793–1797 [2] James T. Wrobleski and David B. Brown, Inorganic Chemistry, 18, 2, (1979) Acknowledgments: JM greatly acknowledge the Funds of his doctoral grant, materials for health, environment and energy, from Tor Vergata. JCG acknowledges the Ramon y Cajal contract (RYC-2015-17722) and the Project from the Retos (MAT2017-86796-R).

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Fe DOPED AlMn2O4 SPINELS AS POTENTIAL CATHODE MATERIALS FOR Al-ION BATTERIES

I. Lozano1, I. Ruiz de Larramendi*1, I. Landa-Medrano1,2, J. Lago1, T. Rojo1,3

1 Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco

(UPV/EHU) Barrio Sarriena s/n, 48940 Leioa-Spain, 2 Cegasa Portable Energy SLU, Lizaur kalea 1, 20560 Oñati-Spain, 3 CIC EnergiGUNE, Albert Einstein 48, 01510 Miñano-Spain

*e-mail: [email protected] Keywords: Al-ion battery, spinel structure Lithium-ion batteries (LIBs) are currently the electrochemical storage systems par excellence because of their high energy density and low self-discharge rate. However, due to the limited availability of Li, exploring new battery concepts based on more abundant and widely distributed elements has become one of the most compelling ambition in the field during the last two decades [1]. In this context, aluminum-ion batteries (AIBs) have recently emerged as promising alternatives to LIBs due to their safety and lower cost, also exhibiting a significant energy density [2]. Thus, aluminum is the most abundant metal in Earth’s crust, presents low reactivity, and is easy to handle. It can also yield high volumetric capacities (up to 8040 mAh/cm3 [3]) due to its relatively high density and the fact that it exchanges three redox electrons per cation. However, previous studies have shown that achievable energy and power densities are cathode-limited in AIBs and, therefore, the design of new cathodes capable of hosting and transferring trivalent Al3+ ions is currently one of the greatest challenges in the development of these devices. Herein we present results on a new family of materials with general formula Al(Mn,Fe)2O4 as potential positive electrode materials for rechargeable AIBs. Different compositions of this family have been synthesized via a sol-gel route and their structural characterization has been carried out by powder X-ray diffraction. Mössbauer spectroscopy and DC-magnetometry have been used in order to determine site distribution of the different cations and to clarify the interactions between different sites in the spinel structure. Finally, their electrochemical activity has been studied by means of cyclic voltammetry and galvanostatic charge-discharge tests, establishing the reversibility of the electrochemical reaction. References [1] S. Gu, H. Wang, C. Wu, Y. Bai, H. Li, F. Wu, Energy Storage Mater., 6 (2017) 9-17. [2] S.K. Das, S. Mahapatra, H. Lahan, J. Mater. Chem. A, 5 (2017) 6347-6367. [3] G.A. Elia, K. Marquardt, K. Hoeppner, S. Fantini, R. Lin, E. Knipping, W. Peters, J.-F. Drillet, S. Passerini, R. Hahn, Adv. Mater., 28 (2016) 7564-7579. Acknowledgments This work has been partially supported by the Spanish Ministerio de Economía y Competitividad (under project MAT2016-78266-P), the FEDER and the Eusko Jaurlaritza/Gobierno Vasco (under project IT-570-13).

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Electrochemical Reduction of CO2 to Formate on Carbon Supported Bismuth Nanoparticles

A. Ávila, L. García-Cruz, V. Montiel, J. Solla-Gullón*

Instituto de Electroquímica, Universidad de Alicante, Apdo 99, 03080 Alicante, Spain [email protected]

Keywords: CO2 electrochemical reduction, formate, bismuth, nanoparticles The electrochemical reduction of CO2 to useful products including formate/formic acid, methanol, ethanol, methane and some others, is an interesting alternative to mitigate global warming effects and, at the same time, producing valuable chemicals. In the last years, very relevant efforts have been performed about this topic [1-5]. In this contribution we report our recent results regarding the electrochemical reduction of CO2 to formate/formic acid using nanostructured bismuth (Bi) electrodes. Briefly, carbon-supported Bi nanoparticles (about 10-12 nm) were prepared using an easy and fast methodology at room temperature. Subsequently, the samples were characterized by using different physicochemical techniques (TEM, XPS and XRD) and, finally, the samples were air-brushed on a carbon paper (Toray Paper TGPH-90). The nanostructured Bi electrodes displayed high selectivity (about 93 % after 3 hours at -1.6 V vs AgCl/Ag) towards the product of interest (formate/formic acid) and also an interesting conversion and stability. References [1] J. Qiao, Y. Liu, F. Hong, J. Zhang. Chem. Soc. Rev., 2014, 43, 631-675. [2] Q. Lu, J. Feng. Nano Energy, 2016, 29, 439-456. [3] Electrochemical Reduction of Carbon Dioxide: Fundamentals and Technologies, Editors J. Qiao, Y. Liu, J. Zhang, 2016, CRC Press, Taylor & Francis Group, ISBN: 9781482258240. [4] J. Gong, L. Zhang, Z-J, Zhao. Angew. Chem. Int. Ed., 2017, 56, 11326-11353. [5] A. Del Castillo, M. Alvarez-Guerra, J. Solla-Gullón, A. Sáez, V. Montiel, A. Irabien. J. CO2 Util, 2017, 18, 222–228 Acknowledgments The authors gratefully acknowledge financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project CTQ2016-76231-C2-2-R (AEI/FEDER, UE). J.S-G. acknowledges financial support from VITC (Vicerrectorado de Investigación y Transferencia de Conocimiento) of the University of Alicante (UATALENTO16-02).

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IN SITU VIDEOELECTROCHEMISTRY OF Zn+Bi2O3 ANODES IN Zn-AIR BATTERIES

F. Vicente*1, F. Santos2, J.J. García-Jareño1, A.J. Fernández Romero2, J. Agrisuelas1

1Departament de Química Física. Facultat de Química. Universitat de València.

C/ Dr Moliner 50 46100 Burjassot (València) 2Grupo de Materiales Avanzados para la Producción y Almacenamiento de Energía, U. Politécnica de

Cartagena, Aulario II, Campus de Alfonso XIII, 30203 Cartagena, Spain *e-mail: [email protected]

Keywords: Anode of Zn+BiO3, video-electrochemistry, Zn-air Batteries Composite electrodes prepared from mixtures of micrometric powders of Zn and BiO3 in different proportions have been studied by video-electrochemical analysis [1]. The study was carried out during the discharge and recharge of a battery using a commercial air electrode (E4B-Electric Fuel) and 6M KOH solution as electrolyte. It has been observed that the material spontaneously undergoes physical chemical transformations in open circuit under these conditions, following the reaction:

Bi2O3 + 3Zn + 3H2O → 2Bi + 3Zn2+ + 6OH−

In this way, the oxidation of metallic Zn causes the reduction of Bi3+ to metallic Bi. This reaction will continue during the discharge while Bi2O3 is present in the material. The reduction of Bi2O3 to metallic Bi causes volume changes that result in cracks observed in the electrode surface images, which can affect the behaviour of the electrode material during the battery charge and discharge cycles. The changes of colour and morphology of the surfaces observed from the video images give a kinetic information of the charge and discharge processes. The decomposition of the images in RGB colours [2] shows abrupt changes that coincide in time with those detected by the Potential-Capacity curves. The methodology tested is useful to characterize the chemical and physical changes of the electrode materials of a battery during the charge/discharge cycles. References [1] F. Santos, J. Abad, M. Vila, G. R. Castro, A. Urbina, A. J. Fernández Romero. In situ synchrotron x-

ray diffraction study of Zn/Bi2O3 electrodes prior and during the discharge of a Zn-air battery. Influence on the ZnO deposition. Electrochim. Acta (In press).

[2] J. Agrisuelas, J.J. García-Jareño, E. Perianes, F. Vicente, Use of RGB digital video analysis to study electrochemical processes involving color changes, Electrochem. Commun. 78 (2017) 38–42.

Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R and ENE2016-79282-C5-5-R.


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CHITOSAN BASED PROTON CONDUCTING MEMBRANES FOR DIRECT METHANOL FUEL CELLS

F. Di Franco*, A. Zaffora, G. Burgio, M. Santamaria

1 Electrochemical Materials Science Laboratory, DICAM, Università di Palermo, Viale delle Scienze,

Ed.6, 90128 Palermo, Italy e-mail: [email protected]

Keywords: Proton conductors, Chitosan (CS)-based membrane, Direct Methanol Fuel Cells To promote Proton Exchange Membrane Fuel Cells (PEMFCs) commercialization, large research effort has been devoted in developing new polymer electrolytes that can replace the usually employed proton conductors, e.g. Nafion®, with other membranes of comparable performances but lower cost. Chitosan (CS)-based membrane electrolyte is currently studied as alternative candidate for PEMFC application. Several works have shown that Heteropolyacids (HPAs) can be used to prepare Chitosan polyelectrolytes (PECs) to be employed as proton exchange membrane in low temperature fuel cell. In previous works [1-4] we have shown that CS/HPA membranes, prepared using alumina porous medium for the slow release of Heteropolyacids, show good performances in H2 fed fuel cell. In literature has been reported that Chitosan (CS)-based membrane are expected to be blocking with respect to methanol cross over [5]. This work is focused on the synthesis and characterization of CS/HPA membranes with the aim to assess the influence of membrane fabrication conditions and nature on their performance as proton conductors in Methanol fed fuel cell (Direct Methanol Fuel Cells). X-ray diffraction and FTIR analyses were performed to study the structure and composition of the membranes, while SEM was used to get information on the membranes morphology and thickness as a function of the preparation conditions. We have also investigated the methanol permeability in order to study the methanol cross over and the water-uptake. The membranes were tested in a Methanol/O2 fuel cell at several temperatures (between 25°C and 80°C). Impedance Spectroscopy was used to get information of the conductivity of the membrane and to model the overall electrical behaviour of the cell. References [1] M. Santamaria et. al., J. Power Sources 276 (2015) 189 [2] C.M. Pecoraro et al., Int. J. Hydrogen Energy, 40 (2015) 14616 [3] M. Santamaria et al., Int. J. Hydrogen Energy, 41 (2016) 5389 [4] M. Santamaria et al., Int. J. Hydrogen Energy, 42 (2017) 6211 [5] Ahmad H et al., Int. J. Hydrogen Energy, 35 (2010) 2160.

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Na-doped Ruthenium Perovskite electrocatalysts with improved oxygen evolution activity and durability in acidic media

M. Retuerto,1 L. Pascual,2 P. Ferrer,3 F. Calle-Vallejo,4 D. Gianolio,3 A. González Pereira,1 A. García

Estévez,1 J. Torrero,1 M. T. Fernández-Díaz,5 P. Bencok,3 M. A. Peña,1 J. L. G. Fierro,1 S. Rojas*1

1Grupo de Energía y Química Sostenible, Instituto de Catálisis y Petroleoquímica, CSIC. Madrid, Spain. 2Instituto de Catálisis y Petroleoquímica, CSIC. Madrid, Spain. 3Diamond Light Source, Harwell Science

and Innovation Campus, Chilton, UK. 4Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands. 5Institut Laue-Langevin, Grenoble, France. *email: [email protected]

Keywords: OER, perovskite, electrochemistry, electrolyser. Oxygen evolution reaction (OER) is crucial in electrolyzers and metal-air batteries. Even with, state-of-the-art Ru- and Ir-oxide catalyst the reaction kinetics is very slow. Mixed oxides are promising OER electrocatalysts. Here we show that SrRuO3 activity and durability for the EOR in acid media can be enhanced by Na+ doping. Sr1-xNaxRuO3 adopts Pbnm perovskite structure and lack oxygen vacancies, so Na incorporation is compensated by Ru partial oxidation. Fig. 1(i) shows the evolution of Ru-O distances inside RuO6 octahedra. SrRuO3 presents a more distorted structure than Sr1-xNaxRuO3. M2,3-edge XANES signal (Fig. 1(ii)) of Na-samples indicate e higher oxidation state of Ru after Na doping.

Fig.1 Sr1-xNaxRuO3: (i) Ru-O distances, (ii) Ru M-edge, (iii) Tafel Plots, (iv) OER durability. Fig. 1(iii) shows the OER activity of Sr1-xNaxRuO3 compared to the best catalysts reported on acid. Sr1-xNaxRuO3 have low Eonset of ~1.36 V (@ j = 0.5 mAcm-2geo), comparable to SrRuO3 and better than similar catalysts. DFT studies reveal that Ru-adsorbate bonds are weaker in Na-doped samples, resulting in highly active Ru sites. The replacement of Sr by Na significantly improves the catalyst’s stability (Fig. 1(iv)). After 20 consecutive OER cycles, SrRuO3 loses 85% of its initial activity while Na-doped samples only 15%. Post-mortem TEM and XAS studies reveal that the perovskite structure remains stable in the Na-doped samples. However, Sr dissolution and RuOx formation is observed after the OER in SrRuO3. This is a remarkable result since most mixed oxides are not even stable in acid. Acknowledgements This work was supported by ENE2016-77055-C3-3-R projects from the Spanish Ministry of Economy and Competitiveness (MINECO). MR thanks MINECO’s Juan de la Cierva program for a grant (FPDI-2013-17582). FCV acknowledges NWO, Veni project number 722.014.009.

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118

Crosslinked Polymer Electrolytes for Safe and High-Performing Lithium-based Batteries

M. Falco, Jijeesh R. Nair†, F. Colò, G. Piana, F. Bella, G. Meligrana, C. Gerbaldi*

GAME Lab, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy), † now at Helmholtz-Institute Münster (HI MS) IEK-12: Ionics in

Energy Storage, Corrensstraße 46, 48149 Münster (Germany) *e-mail: [email protected]

Keywords: Polymer electrolyte, Photopolymerization, Lithium battery

Profoundly ion conducting, self-standing and tack-free ethylene oxide based polymer electrolytes are successfully prepared via a rapid and easily up-scalable free radical polymerization (UV/thermal curing). It can be an interesting alternative to produce polymer electrolytes, being highly advantageous due to its easiness and rapidity in processing, high efficiency and eco-friendliness as the use of solvent is avoided. The crosslinking produced during curing allows the incorporation of high amount of RTIL (e.g., imidazolium, pyrrolidinium) or tetraglyme and lithium salt (TFSI− anion), leading to a material with remarkable homogeneity and robustness. The polymer network can efficiently hold plasticizers without leakage. Samples are thermally stable up to 375 °C under inert conditions, which is particularly interesting for application in Li-ion batteries with increased safety. Excellent ionic conductivity (>0.1 mS cm–1 at 25 °C), wide electrochemical stability (> 5 V vs. Li), stable interfacial properties and dendrite nucleation/growth resistance are obtained. The lab-scale Li-polymer cells assembled with different electrode materials (e.g., LiFePO4, Li-rich NMC, LiCoPO4, TiO2) show stable charge/discharge characteristics with limited capacity fading upon very long-term reversible cycling [1-3].

Fig. 1. Typical appearence of a cross-linked polymer electrolyte with truly elastic characteristics (left) and long-term reversible cycling at ambient temperature in LiFePO4/Li lab-scale polymer cell (right).

The overall remarkable performance of the novel polymer electrolytes postulates the possibility of effective implementation in the next generation of safe and durable secondary Li-based polymer batteries working at ambient and/or sub-ambient temperatures.

[1] J.R. Nair, L. Porcarelli, F. Bella, C. Gerbaldi, ACS Appl. Mater. Interfaces 7 (2015) 12961. [2] J.R. Nair, M. Destro, F. Bella, G.B. Appetecchi, C. Gerbaldi, J. Power Sources 306 (2016) 258. [3] L. Porcarelli, C. Gerbaldi, F. Bella, J.R. Nair, Scientific Reports 6 (2016) 19892.

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119

STUDY OF THE INTERACTION OF TRIAZINE HERBICIDES WITH CU(II) IONS BY ELECTROCHEMICAL MEASUREMENTS

R. Estévez Brito, F. Jiménez Guardeño, R. Rodríguez-Amaro, J. M. Rodríguez Mellado*

Departamento de Química Física y Termodinámica Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, CeiA3, Universidad de Córdoba, Campus Rabanales, Edificio

Marie Curie, E-14071 Córdoba, Spain *e-mail: [email protected]

Keywords: Imidazolinone herbicides, copper complexes, stability constants, electrochemistry, heavy metals pollution Ecofriendly agriculture involves the control of plant protection products, but their uncontrolled use in conjunction of inorganic salts, such as copper nitrate, could cause negative impacts to the ground, water and living organisms. Pesticides and their metabolites are usual contaminants of groundwater. Triazines are pesticides belonging to the group of herbicides used to control weed growth, destroying a wide variety of plants in the first days of germination. Herbicides may have a great impact on metal biocycles in soil, forming complexes with metal ions as Co(III), Mn(II), Ni(II), Cu(II) and others, which have been studied mainly in solid state, but their behaviour in aqueous solutions is poorly known. Copper derivatives are used on crop foliage to control fungical diseases. The aim of this work is to determine the stability constants of the complexes formed by the triazine herbicides with Cu(II) ions, by means of rapid, easy and inexpensive electrochemical measurements (cyclic and differential pulse voltammetry), and to relate the stability of these complexes with the dynamics of the herbicides and the copper ions in the soils. In aqueous solutions of 5<pH<10 (corresponding to the majority of soils of agricultural use) the herbicides form very stable complexes with the Cu(II) ions, being the complexes integrated by two ligands (herbicides) and one copper ion. The table shows the values of the logarithm of the stability constant obtained for the complexes of the herbicides and two related compounds formed with copper ions. Crops treated with such herbicides in conjunction with Cu(II) salts experience a decrease in its persistence and its effectiveness. In addition, both the herbicides and the copper ions may pass to the phreatic layer of the soil, increasing the chance of pollution. Acknowledgments: Financial support from Córdoba University: “Ayudas puente para el desarrollo de proyectos de I+D precompetitivos XX Programa Propio 2015 and XXI Programa Propio 2016”

Compound logKf

CDT a 10.08

SDT b 11.09

Atrazine 11.62

Atraton 8.91

Propazine 11.05

Prometryn 9.95

Prometon 9.71

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120

Reduction of Oxygen to H2O2 at Carbon Felt Cathode in Undivided Cells - Effect of the Ratio Between the Anode and the Cathode Surfaces

Pengfei Ma1,2, Hongrui Ma1, Alessandro Galia2, Simona Sabatino2, Onofrio Scialdone*2

1School of Environment Science and Engineering, Shaanxi University of Science and Technology, Xi’an 710021, China. 2Dipartimento dell’Innovazione Industriale e Digitale, Ingegneria Chimica, Gestionale, Informatica, Meccanica, Università degli Studi di Palermo, Palermo 90128, Italy.

*e-mail: ([email protected] ) Keywords: electrochemical reduction of oxygen, H2O2, ratio between anode and cathode surface; undivided cell; carbon felt. In the last years, the electrochemical conversion of oxygen to hydrogen peroxide at carbon felt cathode has been largely studied since the cathodic generation of H2O2 is a key step for electro-Fenton process [1], which is considered a very promising method for the treatment of wastewater contaminated by organic pollutants resistant to traditional biological processes. In order to improve the performances of the process, many works were devoted to the study of various kinds of cathodes [2]and reactors [3]. In particular, many studies regarding electro-Fenton process were carried out in undivided cells in order to avoid the costs of the separator and to reduce the cell potentials. Hence, in order to optimize the cathodic conversion of oxygen to H2O2, a quite simple and conventional undivided cell equipped with a carbon felt cathode and DSA anode was used for experiments in order to focus the study on the effect of various operating parameters. It was demonstrated that the performances of the process strongly depend on the ratio between the cathode and the anode surfaces. Higher concentrations of H2O2 were obtained using a high ratio between the cathode area and the anode one. References [1] E. Brillas, I. Sires, M. Oturan, Electro-Fenton process and Related Electrochemical Technologies Based on Fenton’s Reaction Chemical, Chem. Rev. 109 (2009) 6570–6631. [2] E. Petrucci, A. Da Pozzo, L. Di Palma, On the ability to electrogenerate hydrogen peroxide and to regenerate ferrous ions of three selected carbon-based cathodes for electro-Fenton processes, Chemical Engineering Journal 283 (2016) 750-758. [3] C.A. Martínez-Huitle, M.A. Rodrigo, I. Sirés, O. Scialdone, Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review, Chem. Rev. 115 (2015) 13362–13407. Acknowledgments University of Palermo is acknowledged for its financial support.


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EC-STM Investigations on Iron-based Macrocycles SAMs as Sources of Fe-N active centres towards ORR

C. Durante*, A. Facchin, T. Kosmala, G. Granozzi, A. Gennaro

Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova, Italy *e-mail: ([email protected])

Keywords: ORR, EC-STM, Fe-N, Fuel Cell, PGM-Free Fe-N-M catalysts are promising materials for replacing Pt catalysts for oxygen reduction reaction ORR in both alkaline and proton exchange membrane fuel cell [1]. In this paper iron(II)-phthalocyanine (FePc) and other iron(III) porphyrins are considered as molecular models for investigating the catalytic properties of Fe-N sites towards ORR by means of Electrochemical Scanning Tunnelling Microscopy (EC-STM). Target molecules were self-assembled on a single crystal Au(111) playing as working electrode (Fe-N/Au), while the STM tip monitored the surface of the sample at atomic scale. Moreover, Fe-N/Au electrode was polarized at precise potentials to register the corresponding surface topographic image, which allowed the evaluation of O2 adsorption/reduction mechanisms on the metal centre and the correlation with the electrochemical response of the system (potentiodynamic imaging). Long-range ordered molecular domains for Iron(II)-phthalocyanine on Au(111) in Ar-saturated 0.1 M HClO4 electrolyte (Fig. 1a), allowed to statistically examine molecular properties thanks to their densely-packed structure. Fig. 1b shows an example of molecular-resolution image. Potentiodynamic imaging was extended to O2-saturated 0.1 M HClO4 to monitor O2 adsorption and subsequent reduction at catalytic sites

Figure 1. (a) Large-scale EC-STM image (70 nm x 70 nm) of FePc-functionalised Au(111) single crystal, It = 2.60 nA; Ub = −358 mV; Eapp = −225 mV; I = −0.1 µA. (b) Small scale EC-STM image (28 nm x 28 nm) of FePc-functionalised Au(111) single crystal, It = 0.55 nA; Ub = −356 mV; Eapp = −226 mV; I = −0.2 µA.

References [1] E. Proietti, F. Jaouen, M. Lefèvre, N. Larouche, J. Tian, J. Herranz, J.-P. Dodelet, Nat. Commun. 2, (2011) 416. [2] G. Binnig, H. Rohrer, Ch. Gerber, . E. Weibel, Phys. Rev. Lett. 49 (1982) 57. [3] M. Wilms, M. Kruft, G. Bermes, . K. Wandelt, Review of Scientific Instruments 70 (1999) 3641.

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PtxY Nanostructures as Electrode Material for ORR in PEMFC

R. Brandiele*, G.A. Rizzi, A. Gennaro and C. Durante

Department of Chemical Sciences, University of Padova, Via Marzolo 1, 35131 Padova e-mail: [email protected]

Keywords: ORR, Fuel Cell, Electrocatalysis, Pt alloys One of the most promising technologies for the increasing demand of energy are the polymer electrolyte membrane fuel cells (PEMFCs). The main challenge for the final commercialization of PEMFC is the cathode side oxygen reduction reaction (ORR), which is extremely slow also at the state of the art Pt based catalyst. Furthermore, the utilization of Pt based catalyst is slowed down by the high cost and low availability of Pt. Recently, the preparation of Pt bimetallic systems has attracted considerable attention because the amount of Pt could be reduced while the catalytic activity and stability may be maintained or even improved, due to the so called "geometric effect" and "ligand effect". From theoretical calculations Pt3Y exhibits the second highest ORR activity ever measured on a polycrystalline electrode, surpassed only by single crystal Pt3Ni (111) and, above all, it has a catalytic activity greater than pure platinum [1]. A new approach to the synthesis of faceted Pt alloy nanocrystals was subsequently developed based on the use of CO gas, that is capable to produce Pt bimetallic nanocrystals with a range of compositions and morphologies (Figure 1a).

In this paper, we describe the synthesis and characterization of PtxY nanoparticles (NPs) supported on a commercial graphitized carbon black. The PtxY NPs were prepared following a solid-state synthesis in a quartz tubular furnace, under H2/CO flow. The influence of temperature, synthesis time and H2/CO gas reduction on NPs shape, dimension, distribution and PtxY alloy formation was investigated by TEM, XRD and XPS analysis. The catalytic activity for ORR was rationalized in terms of NPs shape, dimension and alloy amount. Figure 1b compares the preliminary results on PtxY with a commercial standard (TKK 46 % Pt) and Pt@C synthetized by H2-CO gas.

Fig. 1. a) TEM image of PtxY on CB synthetized at 228°C for 3 h b) LSV of PtxY@CB and Tanaka 50% Pt on rotating disk electrode at 1600 rpm, 20 mV s-1 in 0.1 M HClO4. [1] R. Brandiele, C. Durante, E. Grądzka, G.A. Rizzi, J. Zheng, D. Badocco, P. Centomo, P. Pastore, G. Granozzi, A. Gennaro J. Mater. Chem. A 2016, 4, 12232-12240

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SIMULTANEOUS PESTICIDE AND NITRATE REMOVAL FROM GROUNDWATER

M.P. Bernícola, R. Oriol, E. Brillas, P.L. Cabot, F. Centellas, I. Sirés*


*e-mail: [email protected] Keywords: denitrification, electro-oxidation, electro-reduction, groundwater, imidacloprid The use of synthetic pesticides is widely extended throughout the world as a modern solution to combat all kinds of pests. However, once the pesticide has been used, it automatically becomes a source of pollution in both soil and water. The European Union has included 8 pesticides in the so-called Watch List. All of them are considered as highly toxic, like imidacloprid, which is a kind of neocotinoid [1]. Regulation (CE) Nº 1107/2009 of the European Parliament regulated the use of imidacloprid due to its negative impact on the environment. Furthermore, this pesticide has a strong leaching ability, which leads to the accumulation of a high concentration in groundwater. The removal of imidacloprid in this kind of natural water reservoir yields by-products such as nitrates. On the other hand, groundwater pollution may be also related to the accumulation of nitrate ion from transformation of nitrogenated compounds like ammonia. This pollution is actually derived from a combination of agricultural activity, the nitrogen cycle and the presence of pesticides. Nitrate persists in groundwater because, under oxidative conditions, it is the nitrogen stable form [2]. The World Health Organization establishes a maximum limit of 50 mg/L of nitrate, since above this concentration it becomes harmful to humans [3]. In order to minimize groundwater contamination, transformation electrochemical processes seem a suitable approach. This work presents the simultaneous electrochemical treatment of solutions of 150 mL of groundwater by electroreduction and electro-oxidation processes. The real sample was collected in a small cheese-making factory, which uses groundwater for production after nitrate removal and disinfection with chlorine. Thus, reduction of naturally occurring nitrate and simultaneous oxidative degradation of imidacloprid spiked into the solution were investigated in an undivided electrochemical cell equipped with different cathode and anode materials. The efficacy of denitrification was assessed from the time course of nitrate, ammonium ion generated as intermediate and total nitrogen. The performance of dimensionally stable and boron-doped diamond (BDD) anodes to enhance the mineralization of the pesticide was studied by HPLC, TOC and GC-MS analysis. References [1] J.C.G. Sousa et al., J. Hazard. Mater. 344 (2018) 146-162. [2] M. Gutiérrez et al., Sci. Total Environ. 624 (2018) 1513-1522. [3] OMS. Guidelines for Drinking-Water Quality. Atención Primaria 23 (2006) 7.

Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU).

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TREATMENT OF SOIL WASHING WASTES BY ANODIC OXIDATION WITH DIAMOND ANODES

M.A. Rodrigo*, M. Muñoz-Morales, C. Sáez, J. Llanos, J. Lobato, P. Cañizares

Department of Chemical Engineering. University of Castilla La Mancha. Campus Universitario s/n

13071 Ciudad Real *e-mail: [email protected]

Keywords: electrolysis, diamond anodes, soil washing, chlorinated hydrocarbons Soil washing is a very rapid and effective technology for the removal of hazardous pollutants, which can be successfully used for the fast remediation of acute discharges of pollutants, preventing their diffusion and the subsequent contamination of water reservoirs. It produces a liquid waste from the soil washing fluid used, that can be treated by electrolysis, being very effective the use of diamond anodes, because it may lead to the total depletion of the pollutant transferred from the soil to the washing fluid. When the solubility of the pollutant in water is low, chemicals such as surfactants have to be used in the soil washing in order to obtain a high efficiency and these chemicals become also pollutants in the waste produced. The effect of the competition between these chemicals and the raw pollutants during the electrolysis can be very important, in particular in treatments intended with the final aim of regenerating the initial soil washing fluid. It is also interesting the electrochemical degradation of the colloids formed by the interaction of surfactants and chlorinated hydrocarbons. This work focuses on the removal of organics (perchloroethylene, lindane and clopyralid) from these wastes and describes not only the fundamentals but also innovative approaches designed to attain high efficiencies in their treatment, including not only single electrolysis with diamond anodes but also electro-Fenton and a new combined cell, which integrates electrolysis and soil washing into a single tank. Finally, this work also shows results obtained with an innovative electro-dewatering technology especially developed to minimize the use washing fluid during the soil washing. Acknowledgments: Financial support from the Spanish Ministry of Economy, Industry and Competitiveness and European Union through project CTM2016-76197-R (AEI/FEDER, UE) is gratefully acknowledged

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STUDY OF AN ENERGY STORAGE SYSTEM BASED IN AN ACTIVATED CARBON CLOTH ELECTROCHEMICALLY MODIFIED WITH PPY-AQS AND RGO.

J. Fernández, J. Bonastre, J. Molina and F. Cases*

Dep. de Ingeniería Textil y Papelera, Escuela Politécnica Superior de Alcoy, Universitat Politècnica de València, Plaza Ferrándiz y Carbonell, s/n, 03801 Alcoy, Spain

*e-mail: [email protected] Keywords: Activated carbon cloth; reduced graphene oxide; polypyrrole; anthraquinone sulfonate; electrochemical capacitor.

In the present study, the surface of an activated carbon cloth was modified by coating it with RGO and PPy-AQS using an electrochemical environmentally friendly technique. The use of textiles as substrate for electrodes brings significant advantages related to their high surface/weight and surface/volume ratios and dimensional versatility for the design of electrodes for electrochemical cells. The electrochemical behavior and the capability for energy storage of the modified textile electrodes were evaluated using a three or two-electrode cell configuration. The CV and the charge/discharge tests were used for this purpose. FESEM, FTIR and EIS analyses were used to observe the morphology of different samples, to relate the molecular structure of PPy-AQS with its oxidation state and study the electrical conductivity of the materials, respectively.

The role of RGO in the synthesis of the polymer and the capacitance of the system has been demonstrated in the electrochemical and morphologic analyses. Thus, the combination of RGO with PPy-AQS optimized the electrosynthesis of PPy, increased the areal capacitance and the energy density and reinforced the stability of the polymer with the number of charge/discharge cycles. The values of areal energy and power density of 7.8x10-4 W h cm-2 at 1.8x10-3 W cm-2 obtained in the present work are comparable to those reported in the literature [1-3]. So, promising results for capacitive applications in which electrodes with a high-surface/volume ratio are needed, have been achieved. References: [1] Ch. Choi, K.M. Kim, K.J. Kim, X. Lepró, G.M. Spinks, R.H. Baughman, S.J. Kim, Improvements of

system capacitance via weavable superelastic biscrolled yarn supercapacitors, Nature Communications, 7 (2016), p. 13811. DOI: 10.1038/ncommms13811.

[2] N. Liu, W. Ma, J. Tao, X. Zhang, J. Su, L. Li, C. Yang, Y. Gao, D. Golberg, Y. Bando, Cable-type supercapacitors of three-dimensional cotton thread based multi-grade nanostructures for wearable energy storage, Adv. Mater. 25 (2013) 4925–4931.

[3] W. Liu, N. Liu, Y. Shi, Y. Chen, C. Yang, J. Tao, S. Wang, Y. Wang, J. Su, L. Li, Y. Gao, A wire-shaped flexible asymmetric supercapacitor based on carbon fiber coated with a metal oxide and a polymer, J. Mater. Chem. A 3 (2015) 13461–13467.

Acknowledgments: The authors wish to acknowledge to Chemviron Carbon who kindly donated the ZORFLEX® activated carbon fabric. The authors wish to thank the Spanish Agencia Estatal de Investigación de Economía (AEI) and European Union (FEDER funds) for the financial support (contract MAT2016-77742-C2-1-P).

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A CASE STUDY ON THE TREATMENT OF SWINE WASTEWATER USING A PRE-INDUSTRIAL PLANT WITH ELECTROCHEMICAL AND PHYSICOCHEMICAL STEPS

R. Oriol1, B. Boye2, E. Brillas1, I. Sirés*1

1Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física,

Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain, 2MBI E-Engineering Worldwide, Viladomat 169, 08015 Barcelona, Spain

*e-mail: [email protected] Keywords: circular economy, electrocoagulation, integrated technologies, swine wastewater In Europe, regions like Catalonia have more pigs than inhabitants. Pig slurry, so-called swine wastewater (SW), is a mix of urine, faeces and wastewater that is produced massively in the EU, reaching more than 1 billion cubic meters. This amount cannot be managed simply by spreading it in an uncontrolled manner on the ground, since it gives rise to different kinds of problems such as nitrate accumulation in groundwater. SW does not contain this toxic anion, but ammonia and other nitrogenated compounds are gradually oxidized under the action of soil microorganisms. Currently, the Spanish legislation forbids the spread of wastes through conventional methods (Real Decreto 980/2017, 10 November). Therefore, new technologies are needed, which should be in the form of compact plants to help the farmers to treat the waste on site and, possibly, to ensure waste valorisation. Circular economy encourages these eco-friendly solutions, and SW is a good candidate since it usually contains N, K and even P, which are building blocks for the production of slow-release bio-fertilizers. In this study, a purpose-made pre-industrial plant with capacity to treat up to 5 m3/day has been tested in situ in a swine farm located in the Barcelonès area, with 500 pigs that produce about 10 m3 of SW per day. This is a compact, modular plant that operates in continuous mode, conceived to treat wastewater from strategic productive sectors like dairy, swine or olive oil mill wastewater. The modules include advanced physicochemical units as well as electrocoagulation and electro-oxidation reactors. The goals of this project are: (i) water decontamination for reuse in agricultural irrigation, and (ii) waste valorisation through the generation of a biofertilizer. The physicochemical treatment used as first step has been shown extremely effective, yielding > 90% of K, N and total organic carbon removal (TOC) thanks to the synergy between (electro)coagulation with iron and an advanced separation method. In addition, the enriched sludge contains less than 50% humidity. References [1] Reforma Política Agrónoma Común (PAC) del Ministerio de Agricultura y Pesca, Alimentación y Medio Ambiente, http://www.mapama.gob.es/es/agricultura/temas/pac/ Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU), and technical support from Jorge M. Torrente.

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EFFECT OF A WIDE-RANGE ULTRAVIOLET IRRADIATION ON PHOTOELECTRO-FENTON SYSTEM FOR THE DEGRADATION OF BENZOTHIAZOLES

A. Xu1,2, E. Brillas1, W.Q. Han2, I. Sirés*1

1Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química Física,

Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain, 2Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of

Environment and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

*e-mail: [email protected] Keywords: actinometry, benzothiazoles, photoelectron-Fenton, transformation products Benzothiazoles (BTHs) are routinely used as additives in industrial and household goods. As reported in the literature, the removal of BTHs in conventional wastewater treatment facilities is rather poor. Due to their wide application and biorefractory behavior, BTHs have been detected regularly in all water compartments, including drinking water. Photoelectro-Fenton (PEF) process is considered as one of the most effective electrochemical technologies for the degradation of organic pollutants. In such system, contaminants could be simultaneously treated by multiple direct and indirect oxidation reactions. Ultraviolet light, especially UVA, is employed to accelerate the photolysis of Fe(III)-carboxylate by-products and increase the mineralization of pollutants. However polychromatic UV light including UVA and UVC has not been thoroughly compared in PEF. In this study, the PEF treatment of BTHs has been carried out with a boron-doped

diamond/air-diffusion reactor (Fig. 1), aiming to optimize the current density and Fe2+ content, which was assessed from the contaminants and total organic carbon (TOC) decays. Chemical actinometry was conducted to quantify of the actual absorbed light intensity in solution by single UVA and UVC and by combined irradiation sources. The detailed analysis of the transformation products was made to deduce the degradation pathways. The mechanism of multiple oxidation is also investigated. Fig. 1 Schematic diagram of the wide-range UV in PEF

References [1] L. Wang et al., Environ. Sci. Technol., 50 (2016) 2709-2717. Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU) and PhD scholarship awarded to Anlin Xu (State Scholarship Fund, CSC, China).

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Investigation on Bio-Derived Hydrogel Electrolytes for Dye-Sensitized Solar Cells

F. Bella*1, S. Galliano2, M. Falco1, M. Grätzel3, A. Hagfeldt3, C Barolo2, G. Viscardi2, C.

Gerbaldi1 1 Dipartimento di Scienze Applicate e Tecnologia, Politecnico di Torino, Corso Duca degli Abruzzi 24,

10129-Torino (Italy) 2Dipartimento di Chimica, Università degli Studi di Torino, Via Pietro Giuria 7, 10125-Torino (Italy)

3Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne, Station 3, 1015-Lausanne (Switzerland)

*e-mail: [email protected] Keywords: Dye-Sensitized solar cell, Hydrogel Electrolyte, Design of Experiments Dye-sensitized solar cells (DSSCs) with water-based electrolytes are considered as one of the possible breakthroughs towards DSSCs large-scale diffusion. If opportunely developed and optimized, aqueous solar cells can be considered a truly low impact photovoltaic device and no toxic components [1,2]. Moreover, the possibility of gelling the electrolyte into a polymeric matrix can reduce the leakage outside the device, thus increasing the long-term stability. Above all, bio-derived polymers appear promising being renewable and easy available with low cost [3]. In this contribution, the investigation on bio-derived hydrogel electrolytes for dye-sensitized solar cells is proposed. Moreover, the use of design of experiments (DoE) is demonstrated to be a useful chemometric technique for the concurrent investigation of a series of experimental factors that directly influence the photovoltaic performances of solar cells. Results obtained enlighten that a solid mathematical-statistical approach is fundamental to support the researchers and effectively drive the experiments towards the achievements of optimal operating conditions for aqueous solar cells. [1] S. Galliano, F. Bella, C. Gerbaldi, M. Falco, G. Viscardi, M. Grätzel, C. Barolo, Energy Technol. 5 (2016) 300. [2] F. Bella, S. Galliano, M. Falco, G. Viscardi, C. Barolo, M. Grätzel, C. Gerbaldi, Chem. Sci. 7 (2016) 4880. [3] F. Bella, S. Galliano, M. Falco, G. Viscardi, C. Barolo, M. Grätzel, C. Gerbaldi, Green Chem. 19 (2017) 1043.


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ON THE ELECTROCHEMICAL REDUCTION OF CO2 AT BORON DOPED DIAMOND ELECTRODES IN AQUEOUS MEDIA

S. Palmas*1, L. Mais1, M. Mascia1, A. Vacca1, S. Corgiolu1, F. Ferrara2, A. Pettinau2

1Università degli studi di Cagliari, Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali,

via Marengo 2, 09123, Cagliari (Italy) 2Sotacarbo S.p.A., c/o Grande Miniera di Serbariu, 09013 Carbonia (Italy)

*e-mail: [email protected] Keywords: Electrochemical reduction, Carbon dioxide, BDD, bicarbonate solution The concentration of carbon dioxide in the atmosphere is increased up to 400 mg/l over the last century. This high atmospheric CO2 concentration is related to severe environmental problems, such as global warming; in this context, decreasing the CO2 concentration is a critical issue for a sustainable development. Many efforts have recently been addressed on investigating different pathways to convert carbon dioxide to value-added products and/or through high-energy content fuel [1]. Actually, chemical reduction of carbon dioxide is thermodynamically feasible but only in the presence of strong reducing agents [2]. In alternative, electroreduction of CO2 has been widely studied. Several materials, including metals, semiconductors, metal organic frameworks have been utilized for electrochemical CO2 reduction in recent decades [3]. Conductive boron-doped diamond (BDD) is a material of great interest due to its electrochemical properties, such as wide potential window, low background current, chemical inertness and it has been used for many electrochemical applications. Moreover, the wide potential window and conductive behaviour of BDD electrodes are suitable for supporting CO2 reduction in aqueous media, minimizing hydrogen evolution reactions [4]. In the present work, the electrochemical reduction of CO2 on BDD has been studied in aqueous solution in the presence and in absence of CO2 using bicarbonate solution as electrolyte at different concentration (0.1 M and 0.5 M). Experiments were carried out in a three-electrode cell, in which the working electrode was BDD, while the counter and reference electrodes were a platinum grid and a saturated calomel electrode, respectively. Cyclic voltammograms were recorded in supporting electrolyte and in CO2 saturated solution: several redox peaks were found in the voltammograms carried out at different values of scan rate. The activity of the working electrode was studied in both controlled potential and current electrolyses performed in CO2-saturated electrolyte. Qualitative and quantitative analysis of the liquid products was carried out at the end of electrolysis tests by HPLC, in order to investigate the faradic efficiency and the concentration of the obtained products.

References [1] S. Ohya, S. Kaneco, H. Katsumata, T. Suzuki, K. Ohta, Catal. Today, 148 (2009) 329. [2] G. Centi, E.A. Quadrelli, S. Perathoner, Energy & Environ. Sci., 6 (2013), 1711. [3] J. Low, J. Tu, W. Ho, J. Phys. Chem. Lett., 6 (2015) 4244. [4] K. Nakata, T. Ozaki, C. Tereshima, A. Fujishima, Y. Einaga, Angew. Chem. Int. Ed., 53 (2014) 871.

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HIERARCHICAL TIO2-BASED NANOSTRUCTURES PREPARED BY PULSED LASER DEPOSITION (PLD) FOR PHOTOELECTROCHEMICAL (PEC) WATER SPLITTING

R. Matarrese1, I.Nova1, M. Ghidelli2, B.R. Bricchi2, L. Mascaretti2, A. Li Bassi2, C. Casari2, V.

Russo2, S. Palmas*3, L. Mais3

1Laboratory of Catalysis and Catalytic Processes, Dipartimento di Energia, Politecnico di Milano, via La

Masa 34, 20156 Milano, (Italy) 2Micro- and Nanostructured Materials Laboratory, Dipartimento di Energia, Politecnico di Milano, via

Ponzio 34/3, 20133 Milano, (Italy) 3Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Via

Marengo 3, 09123 Cagliari, Italy *e-mail: [email protected]

Keywords: Photoelectrochemical water splitting, TiO2 Nanostructured materials, Quasi-1D/hierarchical nanostructures, Pulsed laser deposition Photoelectrochemical water splitting can be employed for the production of hydrogen by exploiting solar radiation; however, the development of innovative photoanode materials and architectures still represents a key challenge for the realization of an efficient and competitive PEC cell. Today, nanostructured TiO2 is still the most investigated material although it suffers from two main limitations: poor light absorption in the visible region and limited quantum efficiency for the water splitting process [1]. To overcome these issues, two main strategies have been proposed so far in literature: i) tuning the material structure and morphology, to enhance the active surface, improve light harvesting and minimize charge recombination, and/or ii) doping or sensitization, to shift the absorption towards the visible light. Recently, quasi 1-D hierarchical TiO2 nanostructures prepared by reactive PLD have been proposed as novel photoanodes showing promising results due to optimized total surface area, carrier recombination and electrical transport [2]. This work focuses on the optimization of the material structure-morphology and possible routes for enhancing the photo-response TiO2 films prepared by PLD. This was pursued by varying the deposition atmosphere and the annealing process, also to induce reduction/hydrogenation (the so-called black titania). The combination of TiO2 with gold metal nanoparticles, leading to plasmonic effects, was further investigated, possibly to increase the absorption of visible light and the process quantum efficiency, as well. SEM, Raman spectroscopy and UV-vis-IR spectroscopy were employed to investigate the material morphology, structure and optical properties. The photoelectrochemical water splitting performances were investigated by monitoring the photocurrent generated under illumination in a three-electrode cell. Voltammetric scans and electrochemical impedance spectroscopy analysis were also used to correlate the morphology of PLD samples with their electrochemical properties.

References [1] H.M. Chen et al., Chem. Soc.Rev. 41 (2012) 5654–5671. [2] R. Matarrese et al., J. Solid State Electrochem. 21 (2017) 3139–3154.

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COATING OF COPPER SUBSTRATE WITH POLYANILINE: ELECTROCHEMICAL SINTHESYS AND CORROSION PROTECTION

M. Mascia*, S. Corgiolu, S. Lorrai, L. Mais, S. Palmas, A. Vacca

Università degli studi di Cagliari, Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali,

via Marengo 2, 09123, Cagliari (Italy) *e-mail: [email protected]

Keywords: Copper substrate, Polyaniline, Corrosion current Due to its biocompatibility, chemical and microbial stability, carbon has been largely used as anode material in bio-electrochemical systems; however, its low conductivity represents a severe drawback. This aspect leads to a decrease of the cell voltage, and thus to a decrease of power that, in a scaled-up system, may result in the complete collapse of the electrochemical performance. A limited number of metals may be suitable as anode material: the metal should be electrochemically inert in the operational potential window of the bio-electrochemical system. Copper is known to be a natural antimicrobial material; however, this metal may represent a promising alternative anode material, due to its high conductivity, that permits to minimise the amount of electrode material and thus the material costs. Moreover, contrarily to its usual antimicrobial behaviour, high-performing electrochemically active biofilms have been grown on this metal by Baudler et al. [1]. In the present work, copper substrates have been coated by a conductive polymer, in order to limit the release of copper ions. The surface of copper electrodes was cleaned in HNO3 (20%) and then coated with PANI through a layer – by – layer procedure: a surface grafting by reduction of 4-nitrobenzendiazonium salt was followed by reduction of nitro-groups to amino-groups; PANI was electrodeposited on this under-layer. Different amounts of PANI have been electrodeposited at selected applied current density. Tafel analysis has been conducted, in order to study the corrosion process: the corrosion current and the polarization resistance have been calculated for different amount of PANI, to select the best operative conditions to obtain a substrate suitable for the use in bio-electrochemical systems. References [1] A. Baudler, I. Schmidt, M. Langner, A. Greiner, U. Schroder, Energy Environ. Sci., 8 (2015) 2048

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HETEROGENEOUS ELECTRO-FENTON PROCESS AND ELECTROANALYTICAL TECHNIQUES FOR THE REMEDIATION OF WASTEWATER POLLUTED WITH

IONIC LIQUIDS

M. Pazos1, V. Poza-Nogueira1, M. Arellano1, E. Rosales1, M.A. Sanromán1, E. González-Romero2

1Centro de Investigación Tecnolóxico Industrial - MTI, University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain

2Department of Analytical and Food Chemistry, University of Vigo, Campus Lagoas-Marcosende, 36310 Vigo, Spain

*e-mail: [email protected] Keywords: Ionic liquid; Heterogeneous electro-Fenton; Differential pulse voltammetry; Screen-printed carbon electrode Heterogeneous electro-Fenton (HEF) is a promising technique for the remediation of polluted wastewater, since it overcomes the disadvantages of anodic oxidation and Fenton process. In the present study, HEF was preformed using iron alginate spheres as the catalyst and this treatment was applied for the degradation of two ionic liquids (ILs): 1,3-dicyclohexylbenzimidazolium chloride and 1,3-bis(2,4,6-trimethylphenyl)imidazolinium chloride. Initially, the effect of main variables on the degradation process such as current intensity, catalyst dosage and IL concentration was evaluated. An optimization of those parameters was performed minimizing the energetic consumption at high mineralization level for both ILs. To obtain an in-depth knowledge of the efficiency of the HEF treatments, an exhaustive monitoring of intermediates and by-products was carried out. For that, common methods for the identification and determination of ILs and their degradation products based on analysis with gas chromatography and HPLC techniques were performed. However, these procedures usually require sample pre-treatment and they are very time-consuming. Thus, in this study the application of Differential Pulse Voltammetry (DPV) analysis on Screen-Printed electrodes as transducer, that permits the in situ monitoring of the process, was evaluated. This technique allows to increase the sensitivity and simultaneous analysis of both inorganic and organic species, but also identifies different oxidation states or different complexes. The high removals of IL and total organic carbon achieved, and the identification of carboxylic acids as intermediate products demonstrated the feasibility of this HEF treatment for the mineralization of the ILs under study. In addition, it was confirmed that DPV data permit the identification of the by-products and the evaluation of the ionic interaction of the complex formed along the treatment.

References [1] Rosales E, Iglesias O, Pazos M, Sanromán MA (2012) Decolourisation of dyes under electro-Fenton process using Fe alginate gel beads. J Hazard Mater 213-214:369-377.

Acknowledgments This research was financially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and ERDF Funds (CTM2014-52471-R).

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Hybrid materials composed of nanostructured Conjugated Porous Polymers and TiO2 for Enhanced hydrogen evolution in Photoelectrochemical Cells

Mariam Barawi*1, A. González1, E. Alfonso1, A. García1, C.G López-Calixto1, M. Liras1 and V.

A. de la Peña O´ Shea1

1 Photoactivated Proceses Unit IMDEA Energy Institute, Móstoles Technology Park, Av. Ramón de la Sagra 3, 28935 Móstoles, Madrid, Spain. *e-mail: [email protected]

Keywords: photoelectrochemistry, hybrid materials, energy conversion, hydrogen. Photoelectrochemical water splitting is one of the most interesting alternatives to produce hydrogen in a clean way by solar energy conversion.(1) Despite the huge potential and great advances, new materials need to be developed in order to take this technology to a commercial level. At present, different materials as oxides, oxisulfides and metal chalcogenides are being investigated as photoelectrodes in photoelectrochemical cells. However, achieving high energy conversion efficiencies by using a single material is a very tricky objective. Therefore, hybrid materials are getting a lot of attention lately. (2) In this work, we present a hybrid material formed by the heterojunction of a novel synthesized organic conductive polymer and TiO2 nanocrystals. The nanostructured conjugated porous polymer is based on dithiothiophene moiety (Nano-CMPDTT) and was synthesized by Sonogashira cross coupling reaction from precursors in mini-emulsion conditions. In order to elucidate the electronic structure and the ability of this material to be used as a photocatalyst, HOMO and LUMO positions were determined by cyclic voltammetry. The energy diagram shows an ideal position of the energy bands in order to use the synthesized polymer as an electron injector to TiO2 in photocatalytic reactions. TiO2 NCs and organic polymer suspensions have been deposited by spin coating in ITO glasses. The formed films have been characterized by X-ray diffraction, SEM, EDX and AFM. Photoelectrochemical measurements were performed in a three-electrode cell configuration, using the hybrid material as the working electrode. The hybrid material presents an enhancement in photovoltages and photocurrents values. Electrochemical Impedance Spectroscopy (EIS) was performed to confirm the improved charge transfer observed when illuminating the hybrid material in comparison to the TiO2 nanocrystals alone. In fact, a decrease in the resistance associated with this phenomenon was found. This confirms that the presence of the polymer in the hybrid material increases the absorption of light, charge transfer and reduces electron-hole recombination, making this hybrid a good candidate to be used as a photoelectrode for the hydrogen evolution reaction. In fact, recent results show an improvement in the energy conversion efficiency by using this new hybrid material as electrode compared with regular TiO2.

References [1] Z. Chen, H. N. Dinh, E. Miller, Photoelectrochemical Water Splitting (Springer New York, New York, NY, 2013; http://link.springer.com/10.1007/978-1-4614-8298-7), SpringerBriefs in Energy. [2] M. P. Arciniegas et al., Self-Assembled Dense Colloidal Cu2Te Nanodisk Networks in P3HT Thin Films with Enhanced Photocurrent. Adv. Funct. Mater. 26, 4535–4542 (2016).

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KINETIC MODELLING OF ZINC RECOVERY COMING FROM SPENT PICKLING BATHS

J. Carrillo-Abad*, M. García-Gabaldón, V. Pérez-Herranz

IEC Group, Departamento de Ingeniería Química y Nuclear, Universitat Politècnica de València

Camí de Vera s/n, 46900 València, Spain. P.O. Box 22012, E-46071 Tel.: +34 963877632; Fax: +34 963867639 *e-mail: ([email protected])

Keywords: Galvanostatic operation; kinetic modelling; spent pickling baths; zinc electrodeposition, zin re-dissolution. Amongst all the effluents generated in the hot dip galvanizing industries, the spent pickling baths (SPBs) appears as one of the most hazardous as a consequence of its high content of ZnCl2 and FeCl2 in HCl media [1]. Consequently, they have to be treated previously to their disposal. Although, some experimental procedures permit to recycle the HCl or to separate the components [2,3], none of them permit the recovery of the most valuable component (Zn) back to the process. Then, Zn recovery by the use of an electrochemical reactor becomes an interesting alternative. In previous works, this technology has been able to recover Zn from the SPBs in an efficient way, but the Zn re-dissolution and Fe co-deposition appeared as the main drawbacks [4, 5]. Laboratory experiments were carried out on the electrochemical recovery of the Zn present in the SPB coming from the galvanizing industry. The process was studied under galvanostatic control using a stirred batch electrochemical reactor in the absence/presence of an anion-exchange membrane. The applied current ranged from 150-700 mA. The solutions were prepared similar to 1:50 diluted real SPBs, although some solutions were Fe-free in order to study the effect of this ion on Zn re-dissolution. Two different models have been proposed. On one hand, the model that does not take into account the Zn re-dissolution phenomenon fitted quite well the experimental data obtained with the membrane reactor, as it avoided the adverse effects of the chlorine gas, and consequently, Zn conversion values close to 100% were obtained. On the other hand, a more complex model, which contains a term for the Zn re-dissolution, is used to fit the data of the electrochemical reactor without membrane. An additional term had to be added to fit the Fe containing solutions as it enhances the Zn re-dissolution phenomenon. References 1. Kerney U (1994). Resour Conserv Recycl 10:145–151. 2. Regel-Rosocka M (2010). J Hazard Mater 177:57–69. 3. Carrera JA, Bringas E, Román MFS, Ortiz I (2009). J Memb Sci 326:672–680. 4. Carrillo-Abad J, et al (2012)Sep Purif Technol 98:366–374. 5. Carrillo-abad J, Ortiz-gandara I, Bringas E, et al (2015) Sep Purif Technol 151:232–242. Acknowledgments This work was supported by the European Commission (LIFE16 ENV/ES/000242).

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MICROBIAL ELECTROCHEMICAL TECHNOLOGY AND ION EXCHANGE MEMBRANES: LOW-ENERGY DESALINATION FOR SUSTAINABLE WATER

PRODUCTION Juan M. Ortiz*1, Marina Ramirez-Moreno1, Pau Rodenas Motos1, Abraham Esteve-Nuñez1,2

1Instituto Madrileño de Estudios Avanzados IMDEA Agua, Av. Punto Com 2, 28805 Alcalá de Henares, Spain, 2 Departamento de Química, Universidad de Alcalá, Alcalá de Henares, 28805, Alcalá de

Henares, Madrid (Spain) e-mail: [email protected]

Keywords: microbial desalination cell, desalination, waste water treatment. Microbial Desalination Cell (MDC) is the integration of a MFC and an electrodialysis (ED) cell in order to treat wastewater and desalinate seawater [1]. By using the energy provided by the oxidation of organic matter, contained in the wastewater, this system drives the migration of ions and the desalination process. Thus, MDC technology is able to desalinate saline water without consuming electric or thermal energy and allowing the use of the energy for any other processes. In this sense, MDC technology could be employed to save energy and avoid the greenhouse gases related to the conventional processes (seawater RO produces 1.78 kg of CO2 per m3 using 600 g CO2 kWh-1 in the average European Union (EU) energy mix). The versatile and simultaneous applications of MDC have made it a real and feasible alternative for both desalination and wastewater treatment. In this sense, the merge of microbial electrochemical cells with ion exchange membranes could bring new processes and concepts in the field of waste water treatment and sustainable desalination, opening the chances of integration of such technologies with other biotechnological processes. In this communication, a rational discussion on the future applications of such technology is presented. References [1] Borjas, Z.; Esteve-Núñez, A.; Ortiz, J.M. (2017), Strategies for merging microbial fuel cell technologies in water desalination processes: Start-up protocol and desalination efficiency assessment, Journal of Power Sources, 356, 519-528. Acknowledgement: Project “MIDES – H2020” has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 685793. Juan M. Ortiz acknowledges Ministerio de Economía y Competitividad for the financial support (CTM2015-74695-JIN).


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ELECTROPOLYMERIZATION OF POLY-(O-TOLUIDINE) ON NICKEL ELECTRODES.

A.F. Roig1, J.J. García-Jareño2, J. Agrisuelas2, L. Rivera2, C. Martínez2, E. Guillen2, F. Vicente2

1 Research Institute for Pesticides and Water, Universitat Jaume I, E-12071, Castellón, Spain

2 Departament de Química Física. Facultat de Química. Universitat de València. C/ Dr Moliner 50 46100 Burjassot (València)

*e-mail: [email protected] Keywords: Electropolymerization, Nickel, RGB analysis, Poly o-Toluidine

Polymers based on polyaniline or polyaniline derivatives like poly-o-toluidine (POT) have attracted great interest during the last years due to their stability and good electrical properties [1,2]. Polymerization starts by the generation of radical cations at large anodic potentials. Then the polymer growths covering the electrode surface. Polymerization has been tested on different electrodes materials. However, deposition on metals could present some difficulty since some metals could be oxidized during the electropolymerization process and then, polymer is not generated. In this work, we try a new strategy to electrogenerate POT films on the Ni metal surface. It consists in the previous formation of a protective but conductive layer on the electrode surface before POT electrodeposition. In order to have a richest information about processes taking place, we follow color changes on the electrode by recording digital video at 30 frames per second and then analyzing each frame by decomposing the image into the red, green and blue (RGB) channels [1]. Information obtained from mean color intensity and standard deviation for each channel together with the electrochemical response allows us a better interpretation of the processes. References [1] J. Agrisuelas, J.J. García-Jareño, E. Perianes, F. Vicente, Use of RGB digital video analysis to study

electrochemical processes involving color changes, Electrochem. Commun. 78 (2017) 38–42. [2] J. Agrisuelas, C. Gabrielli, J.J. García-Jareño, H. Perrot, O. Sel, F. Vicente, Polymer dynamics in thin

p-type conducting films investigated by ac-electrogravimetry. Kinetics aspects on anion exclusion, free solvent transfer, and conformational changes in poly(o-toluidine), Electrochimica Acta. 153 (2015) 33–43.



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RGB VIDEO ELECTROCHEMISTRY OF PEDOT SUPERCAPACITOR ELECTRODES

J. Agrisuelas*, J.J. García-Jareño, L. Rivera, C. Martínez, E. Guillen, F. Vicente

Departament de Química Física. Facultat de Química. Universitat de València. C/ Dr Moliner 50 46100 Burjassot (València)

*e-mail: [email protected] Keywords: supercapacitor, conducting polymers, digital video, RGB video electrochemistry

Among π-conjugated conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) has been extensively investigated as supercapacitor electrode because of high electrical conductivity, fast charge/discharge kinetics, wide potential window, and environmental compatibility [1]. Charge storage in PEDOT is due to fast doping/dedoping of counter anions and free solvent into polymer chains accompanied by mechanical swelling and shrinkage of film [2]. Simultaneously, the oxidation state, doping level and structure provides to PEDOT films electrochromic properties [3]. RGB video electrochemistry allows us to analyze the color changes of electrochromic films during any electrochemical experiment with a good resolution [4]. In this work, PEDOT was deposited on ITO electrodes. Color changes electrochemically induced in PEDOT films were monitored by digital video. RGB color changes can be associated to different electrochemical transition in PEDOT and the electrochromic (faradaic) charge and the capacitive charge of these films can be separated. References [1] K. Sun, S. Zhang, P. Li, Y. Xia, X. Zhang, D. Du, F.H. Isikgor, J. Ouyang, Review on application of PEDOTs and PEDOT: PSS in energy conversion and storage devices, J. Mater. Sci.-Mater. Electron. 26 (2015) 4438–4462. [2] J. Agrisuelas, C. Gabrielli, J.J. García-Jareño, H. Perrot, O. Sel, F. Vicente, Electrochemically induced free solvent transfer in thin poly(3,4-ethylenedioxythiophene) films, Electrochimica Acta. 164 (2015) 21–30. [3] J. Meng, X. Li, M. Qin, Y. Pei, S. Yang, Y. Lan, R. Wang, G. Chen, Effects of pore size of reverse opal structured PEDOT films on their electrochromic performances, Org. Electron. 50 (2017) 16–24. [4] J. Agrisuelas, J.J. García-Jareño, E. Perianes, F. Vicente, Use of RGB digital video analysis to study electrochemical processes involving color changes, Electrochem. Commun. 78 (2017) 38–42. Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R


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138

ELECTRODEPOSITION AND ELECTRODISSOLUTION OF NICKEL ON TERNARY GRAPHITE/Cu/POLYPROPILENE ELECTRODES.

J.J. García-Jareño*, J. Agrisuelas, L. Rivera, C. Martínez, E. Guillen, F. Vicente



Keywords: Ni electrodeposition, Composite materials, RGB analysis.

Electrodeposition of metals on different kind of electrode surface reached special interest due to their possible application in different fields such as shielding, electrocatalysis or simply by esthetic purposes. These processes could be schematically represented by the electrochemical process:

𝑀𝑀𝑛𝑛+ + 𝑛𝑛𝑒𝑒− → 𝑀𝑀 In spite of the apparently not complex electrochemical process, this is different for each metal. Among others, adsorption of anions on the electrode surface, the appearance of passive or intermediate layers, parallel reactions such as hydrogen evolution or changes of the surface tension of the solution affect the yield of these processes and makes necessary optimal experimental conditions for each different metal.

Ni corrosion and Ni electrodeposits are among the most studied topics in electrochemistry [1,2]. It is well-known that the mechanism of corrosion or electrodeposition involves different intermediate species and that different Ni hydroxides can be formed on the Ni surface [3]. In this work, we follow the quality of the electrodeposit of Ni on the electrode surface by simultaneously acquiring video of the electrode surface during the electrodeposition and electrodissolution processes. This video was analyzed by separating contributions for each red, green and blue channel and obtaining mean color intensities and standard deviation. In this case, the ohmic drop of the composite material causes the non-electrical uniformity of the electrode surface making easy the electrochemical processes where the ohmic drop effect proves smaller. Another point of interest is the appearance of hydrogen bubbles on the electrode surface, which hinder the electrodeposition process. Different strategies were proposed and tested in order to solve these difficulties and to obtain the most uniformly possible Ni layer on the black composite electrode surface.

References [1] J. Gregori, D. Gimenez-Romero, J. Garcia-Jareño, F. Vicente, Calculation of the rate constants of

nickel electrodissolution in acid medium from EIS, J. Solid State Electrochem. 10 (2006) 920–928. [2] J. Gregori, J.J. García-Jareño, F. Vicente, An approximate theoretical impedance analysis of the

anodic dissolution of nickel across nickel(II) stabilised by means of competitive anions, Electrochimica Acta. 52 (2007) 4062–4072.

[3] M.R. Barbosa, J.A. Bastos, J.J. García-Jareño, F. Vicente, Chloride role in the surface of nickel electrode, Electrochimica Acta. 44 (1998) 957–965.



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139

ELECTROCHEMICAL DEPOSITION OF POLI-(NEUTRAL RED) ON STEEL

T. García-Sancho, J. Agrisuelas, D. Ferrus, A.F. Frau, J.J. García-Jareño, F. Vicente

Departament de Química Física. Facultat de Química. Universitat de València. C/ Dr Moliner 50 46100 Burjassot (València)

*e-mail: [email protected] Keywords: conducting polymers, corrosion

Polymer-based, two-layered structures have been fabricated on top of carbon steel and SS 304 stainless steel electrodes: poly-(Neutral Red) (PNR) [1] and, on top of it, poly-(Azure A) (PAA) [2]. The procedure consisted of two stages: (a) in situ synthesis of PNR on the flat electrode surfaces, followed by (b) CV-driven deposition of PAA from its monomer solution. The potential window employed to synthesize the films was between –1.0 and 1.0 V vs. Hg/Hg2SO4/K2SO4(sat), the scan rate was 10 mV·s–1. In spite of the harsh treatments in salt spray tests, samples of PNR-coated steel samples showed no sign of weathering. On the other hand, PNR-coated carbon steel coupons did show early signs of corrosion. This is consistent with the membrane-like character of such a polymer film, which is capable of exchanging cations and anions with the surroundings. Being PNR an electrochromic material, the procedures based on imaging through optical methods combined with electrochemical techniques provide a practical characterization of the films and its changes. The possibility of depositing PNR thin films atop steel substrates can lead to put forth technological applications other than corrosion issues, such as substrate decoration in the field of surface treatments. References [1] J. Agrisuelas, D. Ferrus, C. Gabrielli, J.J. García-Jareño, H. Perrot, O. Sel, F. Vicente, Poly(Neutral Red) on Passivated Nickel Films. New Insights Through EQCM Measurements, Russ. J. Electrochem. 52 (2016) 1137–1149. [2] J. Agrisuelas, C. Gabrielli, J.J. García-Jareño, H. Perrot, R. Sanchis-Gual, O. Sel, F. Vicente, Evaluation of the electrochemical anion recognition of NO-

3-imprinted poly(Azure A) in mixed solutions by ac-electrogravimetry, Electrochimica Acta. 194 (2016) 292–303. Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R


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140

STUDY BY ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY ABOUT THE EFFECT OF CHEMICAL INHIBITORS ON THE 316 STAINLESS STEEL CORROSION IN

AGRESIVE MEDIA

T. García-Sancho1, S.E. Lemallem2, F. Abdelali2, L.B. Hayet2, J. Agrisuelas1, J.J. García Jareño1, F. Vicente1

1 Laboratorio de Electroquímica. Departamento de Química Física. Universidad de Valencia, C/. Dr.

Moliner, 50, 46100 Burjasot, España. 2 Unité de Recherche de Chimie de l'Environnement et Moléculaire Structurale, University of the

brothers Mentouri, Constantine 25000, Algeria *e-mail: [email protected]

Keywords: EIS, inhibitors, stainless steel, corrosion

Despite of the protective effect of Cr against the corrosion of stainless steel alloys, it is of great interest for the maintenance of construction materials and equipment built with these materials, to have soluble chemical inhibitors in aggressive industrial environments. In this work, the effect caused by the same family of inhibitors is studied using electrochemical impedance spectroscopy (EIS). This technique provides kinetic information about the forced corrosion process, which can be extrapolate comparatively to real processes. 316 stainless steel samples were submerged in 0.1 M HCl solution until constant electrode potential values were reached. EIS were obtained in different concentrations of inhibitors in solution. Nyquist diagrams show an inductive loop caused by the attack of the chloride ions [1,2]. The passive elements of the proposed equivalent circuit are associated with an electronic transfer mechanism followed by the transport of Fe (II) to the solution.

References [1] D. Gimenez-Romero, J.J. Garcia-Jareno, F. Vicente, Analysis of an impedance function of zinc

anodic dissolution, J. Electroanal. Chem. 572 (2004) 235–247. [2] J. Gregori, J.J. Garcia-Jareno, D. Gimenez-Romero, F. Vicente, Kinetic calculations of the Ni

anodic dissolution from EIS, J. Solid State Electrochem. 9 (2005) 83–90. Acknowledgments This work was supported by MINECO-FEDER CTQ2015-71794-R


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141

CO2 ELECTROREDUCTION USING A PEM TYPE REACTOR IN GAS PHASE

F. Martínez*, C. Jiménez, J. García, M.I. Cerrillo, R. Camarillo, I. Asencio, J. Rincón

Facultad de Ciencias Ambientales y Bioquímica (Toledo). Universidad de Castilla-La Mancha. Av. Carlos III s/n

* e-mail: [email protected] Keywords: carbon dioxide, electrocatalytic reduction, supercritical fluids Electrochemical reduction can be considered one of the options with larger potential to reduce anthropogenic CO2 emissions. In this work, the electrochemical reduction of CO2 in gas phase has been carried out in a PEM type cell (Paxitech, 25 cm2 geometric area) in continuous operation mode using carbon nanotube-supported catalysts (Figure 1) [1]. For this process, metal nanoparticles are supported onto carbon nanotubes using a synthesis method based on supercritical fluids. The main products formed from the electrochemical reduction of carbon dioxide have been formic acid, CO, methane, methanol and acetone.

Figure 1. PEM type cell and schematic draw of the electrocatalytic conversion of carbon

dioxide into valuable compounds.

Several metals have been tested in the electrocatalytic reduction of carbon dioxide. Platinum and lead tend to convert carbon dioxide essentially into formic acid. When using copper as catalyst gas products are mainly formed, especially carbon monoxide and methane. References [1] C. Jiménez, J. García, R. Camarillo, F. Martínez, and J. Rincón, Energy & Fuels, 31 (3), 3038–3046,

2017.

Acknowledgments The authors gratefully acknowledge to Ministerio de Ciencia e Innovación of Spain for the financial support to this work through projects CTM2011-26564 and CTM 2016-79098-R.

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142

PHOTOELECTROCATALYTIC DEGRADATION OF PESTICIDES USING WO3 NANOSTRUCTURES

R.M. Fernández Domene*, R. Sánchez-Tovar, B. Lucas-Granados, J. García-Antón

Ingeniería Electroquímica y Corrosión (IEC). Instituto Universitario de Seguridad Industrial, Radiofísica y Medioambiental (ISIRYM). Universitat Politècnica de València. Camino de Vera s/n, 46022 Valencia,

Spain. *e-mail: [email protected]

Keywords: photoelectrocatalysis; pesticides; WO3; anodization; nanostructures Photoelectrocatalysis (PEC) is a technique that combines both electrochemistry and photocatalysis, and it has emerged as a potent tool to eliminate recalcitrant organic compounds in wastewater. PEC processes have several advantages over other advanced oxidation processes (AOPs): they require little to no reagents, hence minimizing the costs associated with additional treatments, and their operation is quite simple. Besides, the fast recombination of photogenerated electron-hole pairs which takes place in photocatalysis is greatly reduced or avoided by applying a small potential polarization to the photoanode, significantly increasing the efficiency of the process by extending the lifetime of holes for the production of hydroxyl radicals. On the other hand, among the most problematic pollutants found in aquatic ecosystems are recalcitrant organic compounds, such as pesticides, drugs or dyes. These compounds and their metabolites are normally non-biodegradable, so conventional biological oxidation treatments are not useful. In this work, tungsten trioxide (WO3) nanostructures synthesized by anodization under hydrodynamic conditions and with very high electroactive surface area have been used to eliminate pesticides from aqueous solutions by photoelectrocatalysis. Previous to the degradation tests, the morphological, electrochemical and photoelectrochemical properties of these WO3 photoelectrodes have been characterized. Acknowledgments: Authors thank for the financial support to the Ministerio de Economía y Competitividad (Project Code: CTQ2016-79203-R) and for the co-finance by the European Social Fund.

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143

DES STABILITY IN THE ELECTRODEPOSITION OF INERT METALS

E. Gómez*, P. Sebastián2, J. M. Feliu2

1Department de Ciència dels Materials i Química Física, Universitat de Barcelona,

2Instituto de Electroquímica, Universidad de Alicante [email protected]

Keywords: Electrodeposition, Ionic Liquids, Deep Eutectic Solvent (DES), solvent stability

Electrodeposition plays a role of paramount importance since it readily allows the deposition of different materials with low energetic cost. For some inert metals, the deposition in aqueous media is limited due to their low hydrogen overpotential. Ionic liquids show wider potential windows and have been used as alternative solvents for electrodeposition. Among them, Deep Eutectic Solvents (DES) are sustainable and handy alternative 1. The present work focuses on investigating the electrodeposition in ionic liquid of two inert metals, Ni and Co, which show useful properties for innovative applications. DES based on choline chloride (ChCl) and urea was used as solvent. The deposition mechanism on different substrates (vitreous carbon, Au, Pt) and its sensitivity to substrate orientation in the first deposition stages (Pt poly, Pt(111)) were studied. At low and moderate overpotentials well-defined structures were obtained. Both on vitreous carbon and gold, the deposit formation shortens the electro-chemical window. At high overpotentials, nickel and cobalt hydroxylated species were detected, as a result of the overlapping of metal deposition and solvent reaction. The stability of the DES was deeply analysed, especially on Pt substrates. Voltammetric structure-sensitive behaviour and hydrogen formation were detected on the Pt bare electrode. Unlike the case of carbon and gold substrates, the presence of deposited Ni and Co promotes the widening of the Pt electrochemical window due to the lower catalytic power of these metals. In addition, the hydrogen formation favours the formation of hydrogenated nickel structures depending of the applied overpotential, these structures being not present in cobalt deposits.

References [1] P. Sebastián; V. Climent; J.M. Feliu, E. Gómez, Ionic liquids in the field of metal electrodeposition in Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Elsevier, 2018

Acknowledgements Financial support from Ministerio de Economía y Competitividad CTQ2016-76221-P and TEC2017-85059-C3-2-R is acknowledged. P. Sebastian acknowledges the award of FPU grant.

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EFFECT OF THE ADDITION OF A PORE GENERATOR ON THE ELECTROCHEMICAL PROPERTIES OF SINTERED (Sb,Sn,Cu)O ANODES FOR EAOPs

J.J. Giner-Sanz1, J. Mora-Gómez1, E.M. Ortega1, M. García-Gabaldón1, S. Mestre2, V. Pérez-

Herranz*1

1IEC group, Depto. Ingeniería Química y Nuclear, Universitat Politècnica de València 2Instituto Universitario de Tecnología Cerámica, Universitat Jaume I

*e-mail: [email protected] Keywords: Ceramic anodes, Pore generator, (Sb,Sn,Cu)O electrodes, Electrochemical advanced oxidation processes (EAOPs), Cyclic voltammetry, Electrochemical impedance spectroscopy (EIS). In the last decades, there has been an astronomical increase of the drinking water demand, due to the exponential growth of the World’s human population. One of the main current worldwide concerns is the growth of water pollution by organic compounds arising from human activities. The great majority of these compounds are persistent organic pollutants (i.e. recalcitrant pollutants), owing to their resistance to conventional wastewater treatments. As a result, these compounds are building up in nearly every water body of the planet. Since the late 80’s, a large number of research teams have focused on developing more effective technologies to totally remove recalcitrant organic pollutants from wastewaters. In this context, electrochemical advanced oxidation processes (EAOPs) have gained increasing attention. Ceramic electrodes based on SnO2 have been widely reported in literature as promising alternatives to the actual state-of-the-art EAOP electrodes (i.e BDDs). A common strategy in electrochemistry for increasing the performance of a given electrode is increasing its electrochemical rugosity factor (i.e. active area per geometric area). In this work, the effect of the addition of a pore generator before sintering (Sb,Sn,Cu)O EAOP anodes was investigated. A common composition was considered for all the electrodes: SnO2 (97.8 wt.%), Sb2O3 (1.0 wt.%) and CuO (1.2 wt.%). Before sintering the electrodes, different amounts of coke, a pore generator, were added. Then, the samples were sintered in a laboratory furnace at 1200ºC. A complete electrochemical characterization of these anodes was done in a 0.1 M Na2SO4 electrolyte. First, cyclic voltametries were performed in the anodic domain at 10 different scan rates; and then, the electrochemical impedance spectrum was measured at 15 different overpotentials. From these measurements, several parameters that are relevant for characterizing the performance of the electrode as an EAOP anode, were obtained: the electrochemical window, the electrochemical rugosity factor, and the oxygen evolution reaction (OER) Tafel parameters. The results were compared with analogue results obtained for Pt and BDD anodes. Acknowledgments The authors are very grateful to the Ministerio de Economia y Competitividad (Projects: CTQ2015-65202-C2-1-R and CTQ2015-65202-C2-2-R) and to the European Regional Development Fund (FEDER), for their economic support.

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DEGRADATION OF NORFLOXACIN PRESENT IN SIMULATED WASTE WATER USING DIFFERENT ANODES

M. García-Gabaldón*1, J. Mora-Gómez1, J.J. Giner-Sanz1, E. Ortega1, S. Mestre2, V. Pérez-

Herranz1

1 Grup IEC Departament d’Engineryeria Química i Nuclear, Universitat Politècnica de Valencia 2 Instituto de Tecnologia Cerámica, Campus Universitario Riu Sec, Av. Vicent Sos Baynat s/n, 12006

Castelló, Spain *e-mail: [email protected]

Keywords: BDD anode, SnO2 ceramic anode, electrochemical oxidation, Norfloxacin, total organic carbon The presence of antibiotic compounds in surface waters is an emerging environmental issue since many of these substances are not biodegradable. Norfloxacin (NOR) belongs to fluoroquinolone antibiotics, and has been used to treat a wide range of gastrointestinal, urinary and respiratory tract infections [1]. These compounds are not effectively removed from contaminated urban wastewaters by conventional municipal treatment plants [2]. Electrochemical oxidation of Norfloxacin (NOR) has been studied in sodium sulphate media using a novel Sb-doped SnO2 ceramic anode and a boron doped diamond (BDD) one in an electrochemical reactor in the presence and absence of an ion exchange membrane. The electrochemistry of the oxidation process strongly depends on the anode type: the Sb-doped SnO2 ceramic anode has lower oxidation power with lower values of TOC (total organic carbon) removal, while BDD acting as a typical anode with high oxidation power mineralizes the organic content to CO2. The use of the membrane to separate the anodic and cathodic compartments is highly favourable as it enhances the anodic reaction kinetics and improves the current efficiency by hampering the occurrence of parasite redox couples. This leads to an improvement of the NOR degradation, the degree of mineralization and the consequent mineralization current efficiency (MCE). The energy consumption per mass unit of total organic carbon is also improved in the divided reactor for both anodes. References [1] K.-J. Huang, X. Liu, W.-Z. Xie, H.-X. Yuan, Electrochemical behaviour and voltammetric determination of norfloxacin at glassy carbon electrode modified with multi walled carbon nanotubes/Nafion., Colloids Surf. B. Biointerfaces. 64 (2008) 269–74. [2] Y. Luo, W. Guo, H.H. Ngo, L.D. Nghiem, F.I. Hai, J. Zhang, S. Liang, X.C. Wang, A review on the occurrence of micropollutants in the aquatic environment and their fate and removal during wastewater treatment, Sci. Total Environ. 473–474 (2014) 619–641. Acknowledgments The authors thanks to Ministerio de Economia y Competitividad (projects number: CTQ2015-65202-C2-1-R and CTQ2015-65202-C2-2-R) and to Fondo Europeo de Desarrollo Regional (FEDER) the support to this research.


MaE-P5

146

ELECTROCHEMICAL ROUTE OF REDUCED GRAPHENE OXIDE ON COCR ALLOY AS ENDOPROTESIC MATERIAL

M.L. Escudero*, M.C. García-Alonso, I. Llorente

1 CENIM-CSIC, Avd/ Gregorio del Amo 8. 28040Madrid. Spain. *e-mail: [email protected]

Keywords: Electrochemical, reduced graphene oxide, CoCr alloy, join prosthesis Being Cobalt-Chromium (CoCr) alloys one of the most commonly materials used for orthopaedic implants as join replacements, the importance of studying their surface modification with graphene-based structures to decrease corrosion and enhanced wearability of implants is of great interest. Nevertheless, it is well known that a complete reduction of graphene oxide (GO) is very difficult irrespectively of the method used so it is already expected the presence of oxygen-functional groups in the electrodeposited reduced-graphene oxide [1-2]. In this work, the main aim has been to deposit graphene-based sheets on CoCr alloy by electrochemical methods. The reduction of a graphene oxide aqueous suspension (4 mg/ml) was carried out by electrochemical methods to generate Electrochemically Reduced Graphene Oxide (ErGO) films on the CoCr alloys. The direct electrodeposition process was performed by two techniques: cyclic voltammetry experiments, and reduction potential. The electrochemical methods were applied after immersion of fresh activated CoCr surface in the aqueous solution of graphene oxide at room temperature. Cyclic voltammetry was performed from -2,1 V to -0,5 V (both referred at Ag/Ag/Cl reference electrode) for 5 scans at 10 mV/min. On the other hand, a reduction potential of -2,1 Vvs. Ag/Ag/Cl was applied for 10 minutes. Characterization of the electrochemically reduced graphene oxide films on CoCr by SEM, and XPS was also carried out. In summary, reduced graphene oxide films grown on CoCr by electrochemical methods used in this work (CV and constant potential) resulted in graphene films which oxygen functional groups are partially reduced and deposited on the CoCr surfaces. Current is successively decreased at the first three cycles in the CV but then remains constant indicating that the reduction on free CoCr areas is finished. In addition, the application of the constant potential does not produce a reduction to zero in the current as time increase but after a threshold value remains constant, indicative that oxygen is retained in the carbon network deposited on the metallic surface. References [1] S.Y. Toh, K.S. Loh, S.K. Kamarudin, W.R.W. Daud, Graphene production via electrochemical reduction of graphene oxide: Synthesis and characterisation, Chem. Eng. J. 251 (2014) 422-434. [2] A. García-Gómez, S. Eugénio, R.G. Duarte, T.M. Silva, M.J. Carmezim, M.F. Montemor, Electrodeposited reduced-graphene oxide/cobalt oxide electrodes for charge storage applications, Appl. Surf. Sci. 382 (2016) 34-40. Acknowledgments: This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness [MAT2015-67750-C3-1].

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ELECTROCHEMICAL CHARACTERIZATION OF nZVI USING SINGLE PARTICLE COLLISION EXPERIMENTS

A.O. Sánchez, C. R. Cabrera*

Department of Chemistry, NSF-CREST Center for Environmental Nanotechnology, University of Puerto Rico at Rio Piedras, San Juan, Puerto Rico 00931

*[email protected] Keywords: Electrochemistry, collision, nZVI, magnetite (Fe3O4), nanoparticle sizing, anodic particle coulometry

During the last decades, single particle detection has opened a novel sight for doing electrochemical characterization of nanoparticles and nanomaterials. Nanoscale zero-valent iron (nZVI) nanoparticles are currently used for environmental remediation due to their ion sequester ability. However, this trait plus their magnetic behavior, and biocompatibility, makes them a promising alternative for heavy metal poisoning treatment, development of MRI dye, and drug delivery loads, among others. Their rapid passivation in aqueous media inhibit their differentiation from magnetite (Fe3O4) by electrochemical methods, due to its surface oxide. Herein, this work is focused on applying the electrochemical method known as anodic particle coulometry (APC) to detect and characterize zero valent iron nanoparticles (nZVI). During the experiments, current blips are observed as a result of a current increase when the electroactive nZVI nanoparticle reaches the Au working ultra-microelectrode surface. Moreover, APC allows for the electrochemical differentiation between nZVI and magnetite (F3O4) by particle size exclusion; not possible using other electrochemical technics such as cyclic voltammetry, or anodic linear sweep voltammetry. This fundamentally drifted experiment aims to elucidate and characterize novel nanomaterials that are currently in use and validate the application of the applied technique. Acknowledgments: This work was supported by NSF-CREST Grant Number 1736093. AOS was supported by NIH-RISE Fellowship Grant No. 5R25GM061151-15. The authors want to thank Dr. Richard M. Crooks and Graduate Student Dr. Alma Castaneda (University of Texas at Austin) for the use of the Nanosight Instrument. Result and experimental discussions with Professor Allen J. Bard (University of Texas at Austin) and Professor Jeffrey E. Dick (The University of North Carolina at Chapel Hill) are greatly appreciated.

TE-P1

148

VOLTAMMETRIC STUDY OF A SURFACE CHARGE TRANSFER PRECEDED BY A CHEMICAL REACTION

J. Gonzalez1, A. Molina1*, F. Martínez-Ortiz1

1Dpto. de Química Física, Facultad de Química, Universidad de Murcia, 30100 Espinardo, Murcia

*e-mail: [email protected] Keywords: CE Mechanism, Monolayer, Voltammetry The electrochemical response of charge transfer processes with surface confined species are very often complicated with non-electrochemical steps whose particular kinetics can affect them in a very decisive way [1]. One of the most frequent is the presence of a previous process due to the existence of a “chemical” reaction (like a protonation reaction), or an “activation” step (i.e., a conformational change or a re-orientation change), that affect to the confined active species [2-4], in line with the following scheme

ox1

2 redad ad adB C D e

kk

k k−→ → +← ← (I)

where 1k and 2k are the rate constants of the preceding process which can be considered as potential independent, and redk and oxk are the rate constants for the electro-oxidation and electro-reduction reactions, respectively. In this communication, we present a theoretical description of electrode process (I), considering the influence of redox and “chemical” kinetics on the overall response by assuming a steady state behaviour for the intermediate species C. The solution presented is valid for a broad range of values of the rate constants of the two processes and, due to its discrete nature, is applicable to any multipotential step technique and it also allows to obtain the continuous limit of Cyclic Voltammetry (CV) for which only numerical calculations had been used previously. The special features of the I-E response for this situation are discussed, with a special focus on the determination of the kinetic parameters of both steps. References [1] Molina, A.; Gonzalez, J. Pulse Voltammetry in Physical Electrochemistry and Electroanalysis, Springer, 2016. [2] Evans, N. H.; Rahman, H.; Davis, J. J. Anal. Bioanal. Chem., 401 (212) 1739 [3] Alvarez-Martos, I.; Ferapontova, E. E., Anal. Chem., 88(2016) 3608 [4] Jeuken, L. J. C. Biochim. Biophys. Acta, 1604(2003)67 Acknowledgments The authors greatly appreciate the financial support provided by the Fundación Séneca de la Región de Murcia (Project 19887/GERM/15) as well as by the Ministerio de Economía y Competitividad (Projects CTQ-2015-65243-P and CTQ-2015-71955-REDT Network of excellence “Sensors and Biosensors”).

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149

THERMODYNAMICS OF NACL IN AQUEOUS MIXTURES WITH CO-SOLVENT ε-INCREASING: AMIDES + WATER AT 298.15 K

F. Hernández Luis*1, R. Rodríguez Raposo1, H. R. Galleguillos2, J. W. Morales3,

G. García García4

1Departamento de Química (U. D. Química Física) Universidad de La Laguna, Tenerife, España 2Departamento de Ingeniería Química, Universidad de Antofagasta, Antofagasta, Chile

3 Escuela de Ingeniería Química, Pontificia Universidad Católica de Valparaíso, Chile 4 LAB 3G, Santa Úrsula, Tenerife, España

*e-mail: [email protected] Keywords: activity coefficients, emf, NaCl, water+amides mixtures, bi-ISE cells, electrolytes Electrolytic aquo-organic media solutions are very important in fields such as chemistry, chemical engineering, biology, biochemistry, bio-electrochemistry, pharmaceutical industry, etc. For this reason, new data on thermodynamic properties of these solutions are always welcome. The coefficients of activity at 298.15 K were determined experimentally using the following electrochemical cell bi-ISE:

Na-ISE | NaCl (m), Amide (Y), H2O (100-Y) | Cl-ISE

Molality (m) varied between 0.01 mol·kg-1 and nearly saturation, while the percentage of amide (Formamide, N-Methylformamide or N-Methylacetamide) in the mixture (Y) ranged from 0 to 100% except by NMA. Applying the Nernst-Nikolsky equation:

E = E0* - 2k log mγ the determination of E0* and k, is performed using the methods of extrapolation of routine along with the classical equations of Debye-Hückel (DH) and Scatchard (S), various modifications of Pitzer equation (P) and the more recent model TCPC (three-characteristic-parameter-correlation). In addition to the coefficients of activity, the Gibbs energy of transfer of NaCl from the aquo -organic mixture to water, product standard solubility of NaCl and the primary hydration number were determined and comparatively analysed for different water - amide mixtures. γ vs. m variation presents the typical profile: sharp initial decline (ion-ion interaction) and a subsequent increase (ion-solvent interaction). A comparative analysis with systems shows how, in all cases, for a given concentration, the γ increase with amide content in the mixture (increase in the dielectric constant of the medium). References [1] F. Hernández-Luis, R. Rodríguez-Raposo, H. R. Galleguillos, J. W. Morales, Fluid Phase Equilibria 425 (2016) 451-464. [2] F. Hernández-Luis, R. Rodríguez-Raposo, D. Grandoso, Journal of Chemical & Engineering Data 56 (2011) 3940-3948. [3] F. Hernández-Luis, R. Rodríguez-Raposo, G. Ruiz-Cabrera, Fluid Phase Equilibria 310 (2011) 182-191.


AWARDS WINNERS LECTURES

“INVESTIGACIÓN CIENTÍFICA”

151

Electrochemical biosensing for reliable and early clinical diagnosis

J.M. Pingarrón

Departamento de Química Analítica, Facultad de CC. Químicas, Universidad Complutense de Madrid, Madrid, 28040, Spain

e-mail: [email protected] Keywords: electrochemical biosensing; clinical diagnosis; cancer; epigenetic biomarkers. Nowadays, it is widely accepted that the prompt and reliable diagnostic of diseases with increasing incidence and prevalence in the last years, such as cancer, is a key factor in the patient survival. Therefore, the demand of efficient, simple and disposable devices with short response times, low-cost, and suitable to perform decentralized and reliable determination of cancer biomarkers for early diagnosis, preferably in a minimally invasive way, which overcome limitations of conventional methodologies, has increased tremendously during the last years. Cancer, earlier thought to be mostly a ‘genetic’ disease is now recognized to involve frequent and widespread ‘epigenetic’ abnormalities, defined as stable, inherited alterations in gene expression which do not involve any change in the DNA sequence and occur at an early stage of the carcinogenic processes preceding genetic changes. Epigenetic alterations include: DNA methylation processes, post-translational histone modifications, chromatin remodeling, and post-transcriptional gene regulation by non-coding RNAs, such as miRNAs. Between them, miRNAs and DNA methylation events are considered nowadays the epigenetic biomarkers with the highest potential for early cancer diagnosis. Taking into account these recent and relevant findings, and just as a small sample of the recent achievements of my research group, the main features of novel electrochemical biosensing platforms for sensitive, selective, simple and rapid determination of miRNAs [1,2] and altered DNA methylation patterns [3,4] will be discussed. The developed methodologies, based on the appropriate use and coupling of novel bioreceptors, functionalized magnetic microcarriers, attractive bioassays formats and electrochemical disposable transducers, both unmodified and nanostructured, demonstrated the accurate determination of the target analytes at clinically relevant levels in scarcely treated challenging biological samples such as cancer cells and tissues (both fresh and formalin-fixed paraffin embedded) and serum from cancer patients. These easy handling bioplatforms with multiplexing capabilities provided results in agreement with conventional methodologies but with lower cost and in remarkably shorter times which make them suitable alternatives in the implementation of user-friendly and affordable devices to perform routine determinations in clinical and basic research settings. References [1] Zouari et al. Biosens. Bioelectron. 91 (2017) 40–45. [2] Zouari et al. ACS Omega (submitted). [3] Povedano et al. Sci. Rep. (2018) 8:6418 | DOI:10.1038/s41598-018-24902-1. [4] Povedano et al. Angew. Chem. Int. Ed. (2018) in press, DOI: 10.1002/anie.201804339.

“JÓVENES INVESTIGADORES”

152

MOVING TOWARDS THE IMPLEMENTATION OF ELECTROCHEMICAL ADVANCED OXIDATION PROCESSES

AS WATER TREATMENT TECHNOLOGIES

S. Garcia-Segura

Arizona State University, Nano-Enabled Water Treatment Research Center, School of Sustainable Engineering and the Built Environment, Tempe (USA), AZ 85281

The ‘Jóvenes Investigadores’ award conference will focus on the fundamentals and recent developements of Electrochemical Advanced Oxidation Processes (EAOPs) towards their implementation as water treatment technologies. Based on the in situ generation of hydroxyl radical (●OH) capable of completely oxidizing organics, emerging EAOPs technologies face environmental impact of persistent organic pollutants. Different EAOPs will be discussed in a comprehensive, comparative and systematic manner emphasizing performance and applicability on the removal of persistent organic pollutants. The evolution of dissolved organic carbon, aromatic intermediates, generated carboxylic acids and released inorganic ions, as well as pollutants decay have been considered to ascertain the degradation rate and mineralization degree achieved for each process. Afterwards, scaling-up and reactors design will be addressed. Special emphasis will be driven towards research challenges and knowledge gaps that must be faced to ensure successful market implementation. Acknowledgments This work was partially funded through the Nano-Enabled Water Treatment Technologies Nanosystems Engineering Research Center by the National Science Foundation of USA (EEC-1449500).

“III ANTONIO ALDAZ”

153

INTERFACIAL REACTIVITY: MODEL SURFACES AND TAILORED SHAPE-CONTROLLED NANOCATALYSTS

R.M. Arán Ais*1,2, E. Herrero3, J.M. Feliu3

1Department of Physics, Ruhr-University Bochum, 44780 Bochum, Germany, 2Fritz-Haber-Institut der

Max-Planck Gesellschaft, 14195 Berlin, Germany, 3Instituto de Electroquímica, Universidad de Alicante, Ap. 99, E-03080 Alicante, Spain.


Keywords: Electrocatalysis; Single crystal electrodes; shaped nanoparticles

Over the past years, extensive research and development have been carried out in low-temperature fuel cells aimed at implementing this technology on transportation, stationary and portable power generation. The fundamental understanding of the electrified interface, as well as the development of highly active and selective catalysts and an optimum technology that improves the effective fuel conversion, are the key challenges for practical application of these devices. The activity and selectivity of the Pt-based nanoparticles (NP) can be modulated by controlling its size and morphology. However, the electrochemical reactions can only be understood if they take place on a clean surface. In this sense, the evaluation of the surface structure and cleanliness by means of electrochemical characterization has been pervasive throughout this work1,2. Moreover, the morphological changes produced in shaped Pt NPs as a consequence of the classical process of electrochemical activation were addressed using identical location transmission electron microscopy (IL-TEM)3. Deeper understanding about the growth mechanism of trimetallic PtNiCo octahedral nanocatalysts was sought after to translate this knowledge into the rational design of synthetic routes, and to study the reactivity of such rationally tailored catalysts for the oxygen reduction reaction (ORR)4. Finally, special attention was paid to the catalysts´ post-treatment procedure, showing the resulting differences in reactivity5.

The work here presented aimed a deeper comprehension of the electrode-solution interface and provided an extended knowledge of the morphology - surface structure – activity - stability relationships for Pt and Pt-based electrocatalysts.

References: [1] ACS Catalysis 2 (2012) 901 [2] Electroanalysis 27 (2015) 945; [3] JACS 137 (2015) 14992; [4] Nano Letters 15 (2015) 7473; [5] Nano Energy 27 (2016) 390401

Acknowledgments: This work was financially supported by the MICINN (Spain), BES-2011-044683.

EC&T Doctoral Program Students Presentations

155

STRUCTURAL AND FUNCTIONAL STUDY OF THE NANO-BIO INTERFACE IN 2- AND 3-D SYSTEMS

M. Chávez


e-mail: [email protected] Keywords: Self Assembled Monolayer, polymer brushes, biocompatibility, Bionanomedicine

One of the largest barriers to the progress in Bionanomedicine has been the lack of knowledge on the properties of the interface between nanomaterials and the biological environment. Proteins present in the biological fluids are considered the first element that can disturb both, the surface properties and the functions for which nanoparticles are designed [1]. To prevent this, surfaces are coated with polymers, such as polyethylene glycol (EGn) that is considered to avoid proteins non-specific adsorption. Recently, many applications of surfaces covered by EGn (organized as polymer brushes) have been reported for medical devices used in diagnostic and therapy systems. The “grafting from” polymerization strategy [2] allows for better control over the efficiency, dispersity and functionalization.

The goal of this PhD thesis is to contribute to the knowledge of the “Nano-Bio” interface. We are attempting to solve problems related to the nature of the interactions between biological systems and nanomaterials, considering both structural aspects (such as the nature of the material, the chemistry of the protective layer and its structure) as well as the interactions between the nanomaterial surface and the biological systems (i.e., with the proteins which form the protein corona, and those between the different proteins within the corona). The advances obtained during the development of this work are aimed at establishing the biocompatibility of the different materials, both in the nanometric and macroscopic systems of the same nature and, with this, contribute to the general knowledge about their properties in order to make them applicable and safe in Bionanomedicine. ADVISERS/MENTORS Teresa Pineda, Universidad de Córdoba References [1] E. Sanfins, C. Augustsson, B. Dahlback, S. Linse, T. Cedervall, Size-dependent effects of nanoparticles on enzymes in the blood coagulation cascade, Nano letters, 14 (2014) 4736-4744. [2] J.O. Zoppe, N.C. Ataman, P. Mocny, J. Wang, J. Moraes, H.-A. Klok, Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes, Chem. Rev., 117 (2017) 1105-1318. Acknowledgments Ministerio de Economía y Competitividad (MINECO) (Proyectos CTQ2014-60227-R and CTQ-2015-71955-REDT Red de Excelencia Sensores y Biosensores Electroquímicos), Junta de Andalucía (P10-FQM-6408) y Universidad de Córdoba.


156

SMART SENSING ELECTROCHROMIC TEXTILES FOR LIVE BACTERIA DETECTION

Amparo Ferrer Vilanova

Institut de Microelectrònica de Barcelona (IMB-CNM-CSIC), Carrer dels Til·lers. Campus UAB, Cerdanyola del Vallès (Barcelona), 08193, Spain.

e-mail: [email protected] Keywords: smart textiles, sensors, electrochromism, Prussian Blue, live bacteria detection. Hospital-acquired infections (HAI) are infections that the patient acquires in the hospital due to contaminated equipment, bed linens or air droplets, among others [1]. In an attempt to minimize it, antibacterial textiles have been developed by incorporation of bactericidal nanoparticles (NPs). These, however, progressively lose their antibacterial activity with time, increasing the risk of contamination and infection. As a strategy to detect bacteria, electrochromic molecules have demonstrated capacity to act as final electron acceptors in the electron transport chain, such as Prussian Blue (PB), which present a different colour for the oxidized and the reduced form [2]. This colour change capacity is here exploited in the development of a smart textile sensitive to the presence of living bacteria with the future goal to be implemented in antibacterial tissues for shelf-life determination. The smart sensing textile is produced by ultrasonic deposition of PB NPs in polyester cotton fabrics, where PB molecules were susceptible to microbial reduction by bacterial metabolism. To demonstrated so, modified fabrics were incubated with bacterial samples of E. Coli and S. Aureus during 24 hours. Samples in contact with microorganism lost their initial blue colour by metabolic reduction of both microorganisms, whereas control samples in culture medium remained blue (Fig.1). Electrochemical and optical assays are currently conducted to characterize, evaluate and improve the potential sensing capacity of the smart sensor. ADVISERS/MENTORS Xavier Muñoz Berbel and María Díaz González, Institut de Microelectrònica de Barcelona (IMB-CNM-CSIC), [email protected], [email protected]. Gonzalo Guirado López, departamento de Química Física UAB, [email protected]. References [1] H. A. Khan, et. Al. Asian Pac. J. Trop. Biomed., vol. 7, no. 5, pp. 478–482, 2017. [2] B. Kong, C. et. Al., Chem. Soc. Rev., vol. 44, no. 22, pp. 7997–8018, 2015. Acknowledgments This work was supported by PROTECT project (H2020-NMBP-PILOT-720851).

Fig.1. Fabrics unmodified and (b) modified with PB 0.45 mM by ultrasonic deposition. (c) Modified fabrics in culture medium. (d) Modified samples after 24 hours of incubation with E. Coli and (e) S. Aureus (OD600nm = 0.001).

157

ELECTROCHEMICAL PAPER-BASED ANALYTICAL DEVICES FOR BIOMEDICAL APLICATIONS

Dmitry Galyamin

Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC) C/ dels Til·lers, Campus Universitat Autònoma de Barcelona (UAB), Bellaterra, Barcelona, Spain

[email protected] Keywords: Paper-based, lateral-flow, nanoparticles In the recent years, various new paper-based diagnostic tools have been developed, more commonly known as PADs (Paper-based Analytical Devices)1. This kind of devices take advantage of particular features of paper such as porosity and capillarity to perform microfluidic functions without the need of dedicated instrumentation. The most common detection method used in this type of platforms is colorimetry. However, there are different disadvantages related to this detection method, the most relevant one being the limited sensitivity offered by instrument-free observation2. In order to increase sensitivity, selectivity and signal quantification, dedicated readers have to be used, which increases both cost and complexity of PADs. Contrarily, electrochemical detection is a more straightforward method towards low cost digital PADs, as it can be fabricated with rapid prototyping techniques and it can be driven with simple instrumentation circuits. However, up to date, not many of these devices are commercially available due several drawbacks such as enzymes stability or limit of detection among others. This work will explore different paths towards the obtaining of a low-cost digital electrochemical lateral-flow test device for point-of-care applications. In order to obtain the best results, a deep study of the effect of the paper matrix on the electrochemical response of different redox species/substrates typically used in electrochemical immunoassays will be carried out by cyclic voltammetry and chronoamperometry. Furthermore, with the purpose of avoiding the use of enzymes, the electrochemical and spectrophotometrical enzyme-like activity of nanoparticles (NPs) will be assessed. ADVISERS Neus Sabaté, [email protected] and Juan Pablo Esquivel, [email protected] Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), 08193-Bellaterra, Barcelona MENTORS Iluminada Gallardo, Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, 08193-Bellaterra, Barcelona, [email protected] References [1] Multilayer Paper-Based Device for Colorimetric and Electrochemical Quantification of Metals. Poomrat Rattanarat, Wijitar Dungchai, David Cate, John Volckens, Orawon Chailapakul, and Charles S. Henry. Analytical Chemistry 2014 86 (7), 3555-3562 [2] A Simple and Sensitive “Dipstick” Test in Serum Based on Lateral Flow Separation of Aptamer-Linked Nanostructures. Liu, J., Mazumdar, D. and Lu, Y. Angewandte Chemie, 2006 118: 8123-8127

158

STUDY OF THE ADSORPTION OF CITRATE ONTO WELL-DEFINED SURFACE GOLD ELECTRODES

J. M. Gisbert-González

1Instituto de Electroquímica, Universidad de Alicante. Apdo. 99, E-03082 Alicante, Spain.

e-mail: [email protected] Keywords: gold, citric acid, nanoparticles The catalytic properties of nanoparticles (NPs) are intimately related to both their shapes and size. Sadly, there is still a vast lack of knowledge in the way of how surfactants act on NPs synthesis, being almost all of them based on empirical results. These properties are of great importance in a wide number of electrochemistry reactions such as those involved in the electrochemical energy conversion and storage. Concerning that fuel cells and batteries are sensitive to the surface structure of catalyzers, it is of great importance to predict how their shape will be. Here, supported by electrochemical experiments we show how a specific capping agent determines the shape of colloidal NPs. In this case, we have studied the adsorption of citrate on Au(111), Au(100) and (110) single crystal electrodes in solutions with different concentrations of citric acid, being HClO4 0.1 M the inert electrolyte. The procedure is exact as it was in the study of citrate adsorption on platinum electrodes, except for the fact that only the desorption current was taken to calculate the total charge densities. Later, both Gibbs excesses and electrosorption valencies were calculated for a complete thermodynamic analysis using the electrode potential and the charge as independent variables.

159

PHYSICOCHEMICAL CHARACTERIZATION OF NANOSTRUCTURED MATERIAL FORMED BY ASSEMBLING POLYMERS ON GOLD

I. Humanes


e-mail: [email protected] Keywords: gold, Self-Assembled Monolayers, polymer, grafting from The need to protect metal surfaces in an industrial way against corrosion, incrustations of biological material, etc., has led to the beginning of lines of research that pursue the modification of surfaces with polymers, converting the growth of brushed polymers into substrates of different nature and form, in a subject of great interest due to the important applications such as anti-corrosive coatings, masks for engravings, lithographs, anti-incrustations, treatments against ice and on photocatalytic surfaces [1].

This PhD project is part of the study of functional interfaces with biocompatible properties. The aim of this work is the characterization of polymeric coatings formed on metals, in particular on gold, modified by self-assembled monolayers (SAMs) of functionalized alkanethiols, with different size, shape and surface characteristics. This is done using a strategy known as grafting from, which is based on a bottom-up approach. The polymer chains are grown through a process of polymerization initiated on the surface, from a SAM modified substrate in which the appropriate functional groups have been introduced. In this way, polymer assemblies anchored on the surface can be prepared with high packing density. The obtention of these hybrid materials, both in nanometric size as in macroscopic substrates and their characterization, constitutes the initial and essential step for their subsequent use in applications in both biological and technological systems. ADVISERS/MENTORS Teresa Pineda Rodríguez, Universidad de Córdoba, [email protected] References [1] J.E. Friis, K. Brøns, Z. Salmi, K. Shimizu, G. Subbiahdoss, A.H. Holm, O. Santos, S.U. Pedersen, R.L. Meyer, K. Daasbjerg, J. Iruthayaraj, Hydrophilic Polymer Brush Layers on Stainless Steel Using Multilayered ATRP Initiator Layer, ACS Appl. Mater. Interfaces, 8 (2016) 30616-30627. Acknowledgments Ministerio de Economía y Competitividad (MINECO) (Proyectos CTQ2014-60227-R and CTQ-2015-71955-REDT Red de Excelencia Sensores y Biosensores Electroquímicos), Junta de Andalucía (P10-FQM-6408) y Universidad de Córdoba.


160

DETERMINATION OF FREE METAL ION CONCENTRATION WITH THE SPECIATION TECHNIQUES AGNES AND DMT

Mireia Lao

Departament de Química, Universitat de Lleida and Agrotecnio, Rovira Roure 191 25198, Lleida Spain

e-mail: [email protected] Keywords: speciation, adsorption, glutathione, zinc, iron, wine, AGNES and DMT. The aim of this work is to study a possible alteration in the electroanalytical technique AGNES (Absence of Gradients and Nerstian Equilibrium Stripping) signal due to the electrodic adsorption. Several systems with induced adsorption have been studied, establishing that when the special AGNES equilibrium situation at the end of the first stage is reached, the existence of other equilibria processes (as adsorption) do not disturb the amount of M0 via different AGNES variants. The analytical signal (current under diffusion limited conditions or charge) is not affected by any process in solution (as adsorption) [1]. AGNES is applied to the study of the system Zn-Glutathione, firstly in synthetic samples and later in root extracts of Hordeum Vulgare. Four different models were introduced in the speciation program VMinteq. Several titrations were performed varying pH and cT,GSH and recording the free metal concentration. Theoretical results of two of the models agree with AGNES determination. In the root extract, the experimental determined concentration was much lower than the predicted one, suggesting the presence of other ligands (as phytochelatins) [2]. In the case of the wine’s study, AGNES and the non-electroanalytical technique DMT (Donnan Membrane Technnique) were used with the aim of comparing the results. Free metal determinations in synthetic wine sample agreed with the predicted ones, but the required time to reach the equilibrium was longer. When working with real wine, it required even longer times. For the ICP-MS analysis of the sample, the method of the isotopic dilution was used. DMT results agreed with the corresponding ones using AGNES [3]. ADVISERS/MENTORS Josep Galceran Nogués & Encarna Companys Ferran, Departament de Química, Universitat de Lleida and Agrotecnio, Rovira Roure 191 25198, Lleida Spain, [email protected] References [1] J. Galceran, M. Lao, C. David, E. Companys, C. Rey-Castro, J. Salvador, J. Puy. “The impact of electrodic adsorption on Zn, Cd and Pb speciation measurements with AGNES”. Journal of Electroanalytical Chemistry, 722-723 (2014) 110-118. [2] M. Lao, A. Dago, N. Serrano, E. Companys, J. Puy, J. Galceran. “Free Zn2+ determination in systems with Zn-Glutathione”. Journal of Electroanalytical Chemistry 756 (2015) 207-211. [3] M. Lao, E. Companys, L. Weng, J. Puy, J. Galceran. “Speciation of Zn, Fe, Ca and Mg in wine with the Donnan Membrane Technique”. Journal of Food Chemistry 239 (2018) 1143-1150.

161

REMOVAL OF CONTAMINANTS OF EMERGING CONCERN FROM GROUNDWATER WITH INTEGRATION OF ELECTROCHEMICAL TECHNOLOGIES

Roger Oriol López


e-mail: [email protected] Keywords: BDD, by-products, DSA®, EAOPs, graphene, groundwater, LC-MS, nitrate, pesticide Contaminants of emerging concern (CECs) include any substance suspected of causing harm to population or ecosystems. However, the term usually refers to chemicals that have been identified in the environment, but whose effects are only recently considered as particularly negative. As a result, new regulations are being established, as occurs for nitrates in groundwater, with a limit of 50 mg L-1 [1], or neonicotinoid pesticides, some of which will be banned soon by the EU. The main goal of this PhD Thesis is to study the performance of electrochemical technologies, either single or coupled with physicochemical processes, to remove organic and inorganic CECs from groundwater and model matrices. Groundwater decontamination has its own implicit problems, such as low conductivity and presence of detrimental ions or natural organic matter (NOM). Furthermore, the direct application of electrochemical technologies (electro-oxidation, electro-Fenton or photoelectro-Fenton) in situ is highly challenging and costly. A more viable approach will be assessed in this Thesis by combination with an adsorption pre-treatment using a novel carbonaceous adsorbent like graphene, in the form of nanoplatelets (GNPs), since the LEMMA has recently shown its good performance to remove organic micropollutants from industrial wastewater [2]. Some specific goals include: (i) study of adsorption isotherms and morphological changes of GNPs; (ii) electrochemical regeneration by different processes to optimize the successive adsorption-regeneration cycles; (iii) elucidation of by-products formed upon regeneration; (iv) integral study of by-products generated in gas phase, combining online and offline GC-MS; (v) treatment of model groundwater pollutants in electrochemical cells coupled to LC-MS, to have in situ information on the degradation routes. The studies will be performed at both, lab-scale (100-250 mL) and pre-pilot scale (3-10 L plant). The electrolyses will be made in the absence or presence of H2O2 electrogeneration, with DSA® or BDD as the anodes. ADVISERS/MENTORS Ignacio Sirés Sadornil, Universitat de Barcelona, [email protected]. References [1] OMS. Guidelines for Drinking-Water Quality. Atención Primaria 23 (2006) 7. [2] N. Flores, F. Sharif, N. Yasri, E. Brillas, I. Sirés. Chemosphere 201 (2018) 807-815. Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU). R. Oriol acknowledges the FPI scholarship awarded by MINECO.

162

UNDERSTANDING ELECTROCHROMIC SYSTEMS: DEVELOPMENT OF “ECO-FRIENDLY” AND LOW-POWER SMART MATERIALS

Sara Santiago Malagón

Departament de Química, Universitat Autònoma de Barcelona, Campus UAB, 08193-Bellaterra,

Barcelona. e-mail: [email protected] Keywords: electrochromism, low-power smart devices, green electrolytes. Electrochromic materials are smart systems that can change colour upon the application of suitable external electric stimuli. The development of electrochromic devices (ECD) (such as ECD display panels, smart windows, antiglare car mirrors or sunglasses and reusable price tags) is a field of great importance nowadays [1]. Hence, an optimum choice of electrochrome and the electrolyte system is critical to ECD performance (Figure 1).

In this sense, this communication focuses on the design of electrochromic systems for the fabrication of smart devices that will work at low potentials. Organic electrochromic materials enable the tuning of redox potentials by design, whereas different formulations of solid-gel “Eco-friendly” electrolytes based on ionic liquids result in higher ionic mobility. Last, especial attention will be paid to establishing the most adequate and cost-effective production method for the mass-manufacture of these electrochromic devices. ADVISERS/MENTORS Gonzalo Guirado López; Departament de Química, Universitat Autònoma de Barcelona; [email protected] F. Javier del Campo; Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus de la Universitat Autónoma de Barcelona; [email protected] References [1] R. J. Mortimer, D. R. Rosseinsky, and P. M. S. Monk, ‘Electrochromic Materials and Devices’, Electrochromic Mater. Devices, vol. 77, pp. 1–638, 2015. Acknowledgments This work was supported by the Agency of Management of University and Research Grants of the Generalitat de Catalunya (program RIS3CAT, Producte Grant SEAMLESS ref.: 2016PROD00114) through ERDF (FEDER) Investment and Growth Operational Programme ‘Catalonia’ 2014-2020

Figure 1. ECD architecture based on an interdigitated configuration using Poly(3,4-propylenedioxythiophene)bis(ethylhexyloxy).

EC&T Master Program Students Presentations

164

COMBINED ELECTRODENITRIFICATION AND ELECTRO-OXIDATION OF GROUNDWATER

María del Pilar Bernícola García


e-mail: [email protected] Keywords: electro-oxidation, electrochemical reduction, groundwater, imidacloprid, nitrate Synthetic pesticides have fostered the intensification of agriculture in recent years. However, they have also become a major source of groundwater pollution due to soil infiltration. The EU has included 8 pesticides in the so-called Watch List. All of them are considered as highly toxic, like imidacloprid, which is a kind of neocotinoid [1]. In 2018, EU members have backed a proposal to ban its outdoor use, since it has been demonstrated as harmful to bees, being these animals very important for food production and the environment. The removal of imidacloprid in these natural water reservoirs yields nitrates. This adds to the contamination that arises from transformation of compounds like ammonia, which may be present in large amounts as a result of manure landfilling. Nitrate persists in groundwater because, under oxidative conditions, it is the nitrogen stable form. The WHO establishes a maximum limit of 50 mg L-1 of nitrate, since above this concentration it becomes harmful to humans [2]. This work discusses the performance of electrochemical transformation processes to minimize groundwater contamination, using a real sample collected in a small cheese-making factory. The treatment of 175-mL solutions of conditioned groundwater (κ = 1.6 mS cm-1, pH = 7.4, 90-130 mg L-1 NO3−, 370 mg L-1 Cl−) through electrochemical reduction and oxidation was carried out in an undivided cell to simultaneously remove natural nitrate and oxidize imidacloprid spiked into the sample (10 mg L-1 TOC). For this purpose, optimization of electrodenitrification was first assessed with different cathode and anode materials, at current densities of 5-50 mA cm-2. The effectiveness of denitrification was evaluated from the time course of nitrate, ammonium ion and chloramine generation, and total nitrogen removal. The performance of a dimensionally stable anode and boron-doped diamond (BDD) to promote the pesticide mineralization was studied by reverse-phase HPLC and TOC analysis, whereas the main by-products were identified by GC-MS and ion exchange HPLC. ADVISERS/MENTORS Ignacio Sirés Sadornil, Universitat de Barcelona, [email protected]. References [1] J.C.G. Sousa et al., J. Hazard. Mater. 344 (2018) 146-162. [2] OMS. Guidelines for Drinking-Water Quality. Atención Primaria 23 (2006) 7. Acknowledgments The authors thank financial support from project CTQ2016-78616-R (AEI/FEDER, EU)

165

OXIGEN ELECTROREDUCTION ON CATALYSTS BASED ON DOPED GRAPHENE MATERIALS

S. Fajardo

Grupo de Ciencias de las Superficies y Electrocatálisis, Departamento de Química – UD Química Física,

Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez s/n, Apartado 456, 38206, La Laguna, Tenerife.

[email protected] Keywords: fuel cells; oxygen reduction reaction; reduced graphene oxide. Fuel Cells (FCs) are promising electrochemical energy converters for a diversity of applications. They have the advantage to provide environmentally friendly energy conversion with a high efficiency and power density. Due to the sluggish kinetic of oxygen reduction reaction (ORR), one of the main research areas for these devices is the development of a highly efficient, low-cost and stable catalyst for this cathodic reaction [1]. Most of catalysts used at the cathode of FCs are Pt-based materials which are very expensive. Moreover, they are not durable and present intolerance towards anode fuel (i.e. methanol or ethanol) in the case of direct alcohol FCs (DAFCs) [2]. Therefore, developing alternative low-cost catalyst with high performance toward the ORR is mandatory for developing FCs and DAFCs. In this work, different heteroatom doped graphene nanomaterials are proposed as electrocatalyst materials for FCs cathode. Graphene nanomaterials (MGs) were synthesized using graphene oxide as precursor. These catalysts were characterized by several techniques, such us X-ray diffraction, Raman spectroscopy, elemental analysis, X-ray photoelectron spectroscopy and transmission electron microscopy. Electrocatalytic activity of MGs was studied by cyclic voltammetry and linear sweep voltammetry using a rotating ring-disk electrode (RRDE). MGs performance in direct ethanol fuel cell (DEFC) was also evaluated. ADVISERS/MENTORS Elena Pastor, Universidad de la Laguna, [email protected]. Pilar Ocón, Universidad Autónoma de Madrid, [email protected]. References [1] Rivera, L. M.; Fajardo, S.; Arévalo, C.; García, G.; Pastor, E. S- and N-Doped Graphene Nanomaterials for the Oxygen Reduction Reaction. Catalysts 2017, 7 (9), 278. [2] Song, C.; Zhang, J. Electrocatalytic Oxygen Reduction Reaction. In PEM Fuel Cell Electrocatalysts and Catalysts Layers Fundamentals and Applications; Springer: London, 2008; pp 89–135. Acknowledgments Authors acknowledge the financial support given by the Spanish Ministry of Economy and Competitiveness (MINECO) through the project ENE2014-52158-C2-2-R (co-founded by FEDER) and ENE2016-77055-C3-1-R.

166

SURFACE ENHANCED RAMAN SCATTERING SPECTROELECTROCHEMISTRY OF GRAPHENE QUANTUM DOTS

L. Lubián-Hernando

Universidad de Burgos

e-mail: [email protected] Keywords: Graphene quantum dot. Raman Spectroelectrochemistry. SERS. Nanoparticles. Abstract: Graphene quantum dots (GQDs) are a new type of carbon nanomaterials with unique electronic and optical properties arising from its quantum confinement, which have many applications in different fields. One of the most interesting characteristics of GQDs is the photoluminescence (PL) of this low-toxic, eco-friendly and chemically inert material [1 ,2] .PL of GQDs depends on its oxidation state. However, this nanomaterial has been scarcely studied by electrochemistry. When GQDs are oxidized or reduced, its electronic structure undergoes important changes, and therefore its spectral properties also change. For this reason, spectroelectrochemistry (SEC) can be considered a fundamental tool to study the evolution of the spectral properties with potential. PL SEC has proven to be very powerful to study PL during the injection/removal of charge[1]. Particularly, Raman SEC provides fundamental information on the vibration modes of carbon. However, Raman sensitivity is very low and, therefore, the use of electrodes that enhance the Raman signal is essential to obtain high quality information. Surface-enhanced Raman scattering (SERS) is the most usual way to increase the Raman signal by using, for example, Ag, Cu or Au nanoparticles (NPs) [3]. Among them, Au NPs seems to be the best option to perform the electrochemical characterization of GQDs because of their higher potential window respect to Ag or Cu. In this work, different AuNPs were chemically synthesized and characterized using electrochemistry, UV/Vis absorption spectroscopy and TEM microscopy. These Au NPs were used to modify carbon screen-printed electrodes that were subsequently used as SERS substrates for SEC. Combination of SERS substrates and SEC allows us to obtain valuable information about the structural changes of GQDs during the injection/removal of charge. ADVISERS/MENTORS Álvaro Colina Santamaría, Universidad de Burgos, [email protected]. José Solla Gullón, Universidad de Alicante , [email protected]. References [1] Barrera, J.; Ibañez, D.; Heras, A.; Ruiz, V.; Colina, A. J. Phys. Chem. Lett. 2017, 8 (2), 531–537. [2] Lim, C. S.; Hola, K.; Ambrosi, A.; Zboril, R.; Pumera, M. Electrochem. commun. 2015, 52, 75–79. [3] Kundu, S. J. Mater. Chem. C 2013, 1 (4), 831–842.

167

DEVELOPMENT AND CHARACTERIZATION OF CARBON ELECTRODES MODIFIED WITH COPPER FOR DETERMINATION OF ANTIOXIDANT CAPACITY

María Teresa Moreno Muñoz

Departamento de Química Física, Instituto Universitario de Investigación en Química Fina y

Nanoquímica IUIQFN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain.

[email protected] Keywords: Carbon Modified Electrodes, Antioxidant Capacity, Copper, Antioxidants. Antioxidants, both natural and synthetic, are frequently used in the conservation of foods. The development of new methods assessing the antioxidant capacity is a main target in last years. Some electrochemical methods have been recently reported [1], but they present limitations dealing with the stability in non-aqueous media and the complexity of their preparations. CUPRAC is a spectrophotometric method based in the reduction of Cu(II) to Cu(I), limited by the color and turbidity of the sample and the working pH. To overcome all these limitations, the aim of this work is to investigate, develop and characterize electrodes based on the electrodeposition of copper on glassy carbon electrodes (GCE), which can be used as sensors for the antioxidant capacity of a wide range of samples. The reduction signal of Cu(II) to Cu(0) has been studied by cyclic voltammetry to establish the range of potentials where the charge-transfer is fast, the growth rate is controlled by the mass transfer and nucleation takes place. Copper electrodepositions were made on GCE from 0.5 M CuNO3 solutions, in acidic media. The potential and time of electrodeposition were optimized. The resulting electrodes were characterized by SEM. The modified electrodes were studied by cyclic voltammetry in phosphate buffer solution at pH 7. The stability and reproducibility of the electrodes were established by monitoring the anodic and cathodic peaks, and these parameters were related to the structure of the surfaces observed by SEM. In the presence of antioxidants (Ascorbic acid, Gallic acid and Trolox), the reduction signal in the reverse scan decreases when the concentration of antioxidant increases and, consequently, the electrode modified with copper (nano and/or aggregated) particles can be used to evaluate the antioxidant capacity. The electrodes have been optimized for their use in this way. ADVISERS/MENTORS José Miguel Rodríguez Mellado, Departamento de Química Física, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Universidad de Córdoba, Campus de Rabanales, Edificio Marie Curie, E-14071 Córdoba, Spain. [email protected] References [1] M.P. Rivas Romero, R. Estévez Brito, A. Palma, M. Ruiz Montoya, J.M. Rodríguez Mellado, R. Rodríguez-Amaro, J. Electrochem. Soc., 164 (2017) B97-B102 (and references cited)

168

EVALUATION OF PAPER-BASED ETHANOL FUEL CELLS FOR ALCOHOL DETECTION IN SALIVA

M. Navarro-Segarra

Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), C/ del Til·lers, Campus UAB, 08193 Bellaterra, Barcelona (Spain), [email protected] Keywords: saliva ethanol sensor, direct ethanol fuel cell, paper device, palladium The development of simple and low-cost point-of-care and on-site monitoring devices that fulfil clinical, environmental and industrial demands continue increasing [1]. Disposable sensors based on screen-printed carbon electrodes give the possibility of satisficing both practical and economic interests in a very simple, smart, affordable and ultimately user-friendly way [2]. This work presents a new alcoholmeter for saliva testing based on a paper fuel cell. Screen-printed carbon electrodes were employed as anode and cathode. Ethanol catalysis takes place at the anode, whose carbon surface has been modified with a palladium nanoparticle suspension. The anode was coupled to a non-limiting silver peroxide modified cathode. Paper was used as cell matrix to hold the saliva electrolyte. The ethanol oxidation catalysis reaction was studied with a 100mM KOH buffer containing ethanol within the range of 1 to 80mM. The activation protocol of the palladium-based anode has been optimized in order to obtain a linear response within the whole range of concentrations and the correlation between the fuel cell power output and the content of ethanol in the sample has been evaluated. The device holds promise to be an effective system to monitor alcohol content in human saliva as an alternative to the blood analysis gold standard. ADVISERS/MENTORS Neus Sabaté 1,4, [email protected], Juan Pablo Esquivel 1, [email protected] Sergio Rojas 2, [email protected], Elvira Gómez Valentín 3 (Tutor), [email protected] 1 Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193, Bellaterra, Barcelona, Spain 2 Instituto de Catálisis y Petroleoquímica, ICP (CSIC), C/ Marie Curie 2, 28049, Cantoblanco, Madrid, Spain 3 Departament de Ciència de Materials i Química Física, Universitat de Barcelona 4 Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluís Companys 23, 08010 Barcelona, Spain References [1] P.B. Luppa et al. Trends Anal. Chem. 30 (2011) 887–898. [2] J.P. Hart &, S.A. Wring, Trends Anal. Chem. 16 (1997) 89–103.






169

THREE-DIMENSIONAL GRAPHENE-BASED MICROELECTRODE ARRAYS FOR NEURAL INTERFACES

Peña Díaz. M

Catalan Institute of Nanoscience and Nanotechnology (ICN2), Av. De Serragalliners s/n, Bellaterra

08193, and Autonomous University of Barcelona (UAB), Bellaterra 08193; Barcelona, Spain. [email protected]

Keywords: graphene, graphene oxide, one-step electrodeposition, 2D materials, microelectrodes

The direct electrical interfacing of graphene-based devices with individual neurons is currently being considered for the development of the next generation of neuroprosthetic devices. Graphene is as a very good candidate for electrical interfacing with electrogenic cells due to its remarkable chemical and physical properties. Furthermore, graphene is known to possess good biocompatibility and can be easily integrated in flexible devices, which is crucial in neuroprosthetic applications. For these applications, a large electroactive area and a porous material reduce the impedance thereby improving the recording and stimulation performance [1]. The aim of this project is to explore an alternative synthesis of porous graphene-based electrodes through the electrodeposition of graphene oxide on platinum electrodes [2]. For that, electrodeposited reduced graphene oxide (eRGO) coatings were synthesized by cyclic voltammetry and by chronopotentiometry techniques. The physical characterization of eRGO has been carried out with Raman spectroscopy and SEM in order to analyse the reduction level of the graphene and its structure. Furthermore, electrochemical techniques such as cyclic voltammetry using the redox couple [Fe(CN)6 ]3-

/[Fe(CN)6]4- and electrochemical impedance spectroscopy have been used to study the electrode response before and after modifications. This new synthesis method will enable the fabrication of porous graphene microelectrodes arrays (MEAs) with 3D shapes, unlocking the limitation that they currently have to 2D arrays.

ADVISERS/MENTORS ICREA Prof. Jose A. Garrido, Catalan Institute of Nanoscience and Nanotechnology (ICN2), [email protected]. Prof. Iluminada Gallardo, Autonomous University of Barcelona (UAB), [email protected]. References [1] Kostarelos, K., Vincent, M., Hebert, C. and Garrido, J. “Graphene in the Design and Engineering of Next-Generation Neural Interfaces”. Advanced Materials. 29(42) (2017): p.1700909. [2] Molina, J., Fernández, J., García, C., del Río, A., Bonastre, J. and Cases, F. “Electrochemical characterization of electrochemically reduced graphene coatings on platinum. Electrochemical study of dye adsorption”. Electrochimica Acta, 166 (2015): pp.54-63. Acknowledgments This work has been partially supported by the European Union’s Horizon 2020 research and innovation programme under Grant Agreement Nº 696656 (Graphene Flagship). The ICN2 team was supported by the Severo Ochoa program from Spanish MINECO under Grant Nº SEV-2013-0295 and by the CERCA Programme from Generalitat de Catalunya.


170

POLYPYRROLE REACTIONS SENSE ELECTROLYTE CONCENTRATIONS.

Emil Tavárez

1Laboratory of Electrochemistry Intelligent Materials and Devices, Technical University of Cartagena, ETSII, Campus Alfonso XIII, 30203, Cartagena, Spain

e-mail: [email protected] Keywords: conducting polymers, molecular machines, conformational movements, sensing reactions, propioception. Those polypyrrole films were employed in this work are constituted by electrochemical molecular machines. The oxidation/reduction of the material mimics the intracellular matrix of muscle cells. The material has been synthesized on Pt by flow of a constant current through a monomeric solution. The reproducibility of the electrogeneration of the process was checked by voltammetric and gravimetric control. The influence of the electrolyte concentration on the reversible oxidation/reduction of the synthesized polypyrrole films was studied by potential sweeps, square potential waves or square current waves in various NaCl aqueous solutions. The evolution of the consumed energy by the reaction or that of any of Its components (charge and potential) vary as a function of (is a sensor of) the electrolyte concentration: the energy consumed by the reaction adapts to, or senses, the chemical energy of the reaction media. A theoretical description of the attained results is presented getting the sensing equation. Identical conclusions were attained employing NaSCN aqueous solutions. ADVISERS/MENTORS Toribio F. Otero, Laboratory of Electrochemistry Intelligent Material and Devices, Technical University of Cartagena, ETSII, Campus Alfonso XIII, 30203, Cartagena, Spain, e-mail: [email protected] References [1] T. F. Otero, Conducting Polymers: Bioinspired Intelligent Materials and Devices, RSC, 2015. [2] T. Otero, J. Martinez, J. Arias-Pardilla, Electroquimica Acta. 84 (2012) 112-128. [3] Handbook of Conducting Polymers. (Third Edition) T. A. Skotheim y J. R. Reynolds. CRC Press, Boca Ratón (2007) [4] T. F. Otero, J. G. Martinez, Prog. Polym. Sci 44 (2015) 62-78.

171

EFFECT OF FexCoy OBTAINED BY MECHANICAL ALLOYING ON ELECTROCATALYTICAL ACTIVITY FOR THE OXYGEN REDUCTION REACTION

Xiaolei Xu

Universidad Autónoma de Madrid, Depto. Química Física aplicada, C/Francisco Tomás y Valiente 7,

28049, Madrid, Spain E-mail: [email protected]

Keywords: FeCo alloy; Mechanical alloying; Oxygen Reduction Reaction (ORR); FeCo catalyst; Non-noble metal electrocatalyst Abstract: Transition metal has an important effect on the electrocatalytic activity of non-noble metal catalysts for Oxygen Reduction Reaction (ORR) [1]. In the present work, FexCoy alloyed particles were synthesized from high purity powders (Fe and Co) by means of the high-energy mechanical alloying. ORR electrocatalytic performance of the FexCoy alloys in acidic and alkaline media was evaluated by a rotating disk electrode (RDE) at room temperature. The structure of the catalysts was investigated with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Small-particle clusters with granular morphology and micro-metric sizes were obtained in all the cases. According to the RDE results, the prepared catalysts exhibit high electrocatalytic activities toward ORR under alkaline conditions, while the electrocatalytic activity under acidic conditions was not very ideal. The Fe80Co20 presents the highest electrocatalytic activity for ORR in both electrolytes (acidic and alkaline). ORR current density at 2000 rpm was 0.09 mA/cm2 @0.1 V (vs Ag/AgCl) in acidic solution and 3.52 mA/cm2 @-0.6 V (vs Ag/AgCl) in alkaline solution. Therefore, the chemical composition of Fe/Co played an important role in the electrocatalytic activity of these non-noble metal catalysts for ORR.

References: [1]: Banham, Dustin, et al. "A review of the stability and durability of non-precious metal catalysts for the oxygen reduction reaction in proton exchange membrane fuel cells." Journal of Power Sources 285(2015):334-348. Advisers/Mentors Pilar Herrasti González; Depto. Química Física Aplicada-Universidad Autónoma de Madrid, [email protected]. Nieves Menéndez González; Depto. Química Física Aplicada-Universidad Autónoma de Madrid, [email protected].

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