In-situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis

Preface

Chapter 1. In situ FTIR studies on the acid-base equilibria of adsorbed species on well-defined metal electrode surfaces

Antonio Berná, Antonio Rodes, Juan M. Feliu

1. Introduction2. Experimental3. Results3.1 Experimental results for M(111) electrodes in CO2-saturated solutions3.2 The influence of pH upon oxalic acid adsorption on platinum single crystal electrodes3.3 The influence of the surface structure on the surface acid-base equilibria of oxalic acid4. Discussion and conclusions4.1 Carbon dioxide adsorption4.2 Oxalic acid adsorption5. Concluding remarks6. Acknowledgements References

Chapter 2. Contributions of External Reflection Infrared Spectroscopy to Study the Oxidation of Small Organic Molecules

Teresa Iwasita, Giuseppe A. Camara

1. INTRODUCTION2. ELECTROCATALYSIS OF CO OXIDATION2.1 Carbon Monoxide Electrooxidation: adsorbed vs bulk CO2.2 Potential dependent FTIR spectra of CO adlayers at Pt (111)2.3 The OH stretching region2.4 The dependence on the admission potential2.5 The inhibition of CO bulk oxidation3. ELECTROCATALYSIS OF METHANOL OXIDATION3.1 The Influence of the Base Electrolyte on Methanol Oxidation as demonstrated in FTIR spectra3.2 Time dependence of the band intensity for CO2. Kinetic implications3.3 The yields of methanol oxidation pathways3.4 On the mechanism of methanol oxidation3.5 The parallel reactions and the catalysis of methanol oxidation by PtRu4. ELECTROOXIDATION OF ETHANOL4.1 The Influence of Ethanol Concentration on the Oxidation Pathways4.2 The influence of the catalyst: Ethanol oxidation on PtRu electrodeposits5. Concluding remarks

References

Chapter 3. Contribution of in situ Infrared Reflectance Spectroscopy in the study of nanostructured fuel cell electrodes

Jean-Michel Léger and Françoise Hahn

Introduction1. Fuel cells and Electrocatalysis2. In situ infrared reflectance spectroscopy 3. Introduction4. Methods5. In situ reflectance spectra6. In situ infrared reflectance spectroscopy studies of reactions involved in fuel cells 7. Introduction8. Cases of CO and methanol oxidation at PtRu bulk alloy electrodes.9. Preparation of nanostructured electrocatalysts10. Influence of particle size11. Effect of the structure of nanoparticles: example of Pt-Ru/C.12. Adsorbed CO poison or reactive intermediate for methanol oxidation?13. Oxidation of ethanol at Pt-Sn/C.14. Mobility of CO at the electrode surface.15. Behavior of trimetallic platinum-based nanostructured electrocatalyst.16. Electroreduction of oxygen17. Conclusion18. Acknowledgments References

Chapter 4. In-situ FTIR spectroscopic studies of the adsorption and oxidation of small organic molecules at the Ru(0001) electrode under various conditions

Wen-Feng Lin, Paul A Christensen and Jia-Mei Jin

1. Introduction 2. Experimental 3. Results and discussion 1. Surface structure and electrochemical characterization of the Ru(0001) electrode in

perchloric acid solution 3.2. Reactivity of the Ru(0001) electrode towards the adsorption and electrooxidation of CO

in perchloric acid solution as a function of temperature 3.2.1. The FTIR data at 25 C 3.2.2. The FTIR data at 10 and 50 C 3.2.3. Comparison of rate of oxidation of the CO adlayer at constant potential at 10, 25 and 50 C 3.2.4. Surface relaxation and compression of the sub-monolayer CO adlayer 3.3. Reactivity of the Ru(0001) electrode towards the adsorption and electrooxidation of

formaldehyde, formic acid and methanol as a function of temperature 3.3.1. Formaldehyde electrooxidation

3.3.2. Formic acid electrooxidation 3.3.3 Methanol electrooxidation 3.4. Reactivity of the Ru(0001) towards the oxidation of CO adsorbates under open circuit

conditions 3.4.1 The open circuit oxidation of CO adsorbates on the Ru(0001) in perchloric acid solution 3.4.2 The open circuit oxidation of CO adsorbates on the Ru(0001) electrode in sulfuric acid

solution 3.5. The possible mechanisms of CO oxidation under open circuit conditions — a comparison

of the data obtained at gas/solid and electrolyte/solid interfaces 4. Concluding remarks References

Chapter 5. In situ microscope FTIR reflection spectroscopy and its applications in electrochemical adsorption and electrocatalysis on nanostructured surfaces

Shi-Gang Sun and Zhi-You Zhou

1.Introduction2. Instrumentation and principle of in situ microscope FTIR reflection spectroscopy

(MFTIRS)2.1 The setup of MFTIRS2.2 The principle of MFTIRS2.3 The technology of in situ time-resolved MFTIRS4. Surface combinatorial studies of anomalous IR properties of nanostructured surfaces of

Pt and Ru using in situ MFTIRS3.1 The individua1 addressable array of microelectrode (IAM)3.2 The combination of in situ MFTIRS with the IAM3.3 Nanostructured Pt thin films constructed through the induction of fast potential cycling (FPC)3.4 Nanostructured Pt thin films formed through square wave potential cycling3.5 Nanostructured Ru thin films prepared through electrodeposition4. Studies of electrochemical kinetics using SSTR-MFTIRS4.1 Characterization of the SSTR-MFTIRS4.1.1 The time constant of the in situ IR cell4.1.2 Design of microelectrode for SSTR-MFTIRS4.1.3 Dynamics of CO adsorbed on nanostructured surfaces4.2 Dynamics of irreversible reaction on nanostructured surfaces4.2.1 The design of flow thin layer IR cell and microelectrode4.2.2 The kinetics of CO oxidation5. Studies of electrocatalytic oxidation of methanol on nanostructured Pt using rapid-scan time-

resolved MFTIRS (RSTR-FTIRS)5.1 RSTR-MFTIR spectra of methanol oxidation5.2 Dynamic processes of methanol oxidation5.3 Mechanism of methanol oxidation on

nanostructured Pt microelectrode in alkaline solutions6. SummaryAcknowledgementsReferences

Chapter 6. IR spectroelectrochemistry: instrumentation and applications of external reflection, ATR and transmission sampling

C. Korzeniewski

1. INTRODUCTION2. INSTRUMENTATION AND SPECTRAL ACQUISITION METHODS 2.1. In situ sampling methods2.2. Spectrometer systems 2.3. Sensitivity considerations3. APPLICATIONS3.1. Recent applications of external reflection sampling for studies in electrocatalysis3.1.1. Single crystal electrodes3.1.2. Bimetallic Electrodes 3.1.3. Nanoparticle catalysts3.2. External reflection sampling for quantitative studies of molecular orientation on

electrodes3.3 Applications of SEIRA spectroscopy in electrochemistry3.4 Applications of transmission infrared sampling in electrochemistry3.4.1. Spectroelectrochemistry of redox proteins 3.4.2. Quantitative CO2 determinations3.4.3. Studies of polymer electrolyte membrane 4. Summary

References

Chapter 7 Electrocatalytic Reactions on Platinum Electrodes Studied by Dynamic Surface-Enhanced Infrared Absorption Spectroscopy (SEIRAS)

M. Osawa

1. Introduction2. Mechanism of SEIRA3. Experimental aspects

3.1. Electrochemical cell and optics3.2. Preparation of thin film electrodes

4. Selected examples4.1. Adsorption and oxidation of CO on Pt4.2. Formic acid oxidation

4.2.1. Combined CV and SEIRAS measurements4.2.2. Reaction intermediate4.2.3. Kinetics of formic acid oxidation4.2.4. Electrochemical oscillations in formic acid oxidation

4.3. Methanol Oxidation4.3.1. Reaction intermediate in the direct path4.3.2. Oxygen source for CO oxidation

4.4. Hydrogen evolution and oxidation on Pt 4.5. Other electrocatalytic reaction systems5. Summary and future prospects

AknowledgementsReferences

Chapter 8In-situ spectroscopy of operating fuel cellsEugene S. Smotkin

1. Introduction2. Infrared reflectance spectroscopy of CO adsorbed on arc-melted Pt alloy surfaces3. Infrared spectroscopy of CO adsorbed on MEA surfaces in operating fuel cells 4. X-ray absorption spectroscopy of operating fuel cells5. Summary

References

Chapter 9 Vibrational and electronic spectroscopic investigation of the electrochemical interface using IR-Visible Sum Frequency Generation and related nonlinear optical techniques

Abderrahmane Tadjeddine, Franck Vidal

1. Introduction2. Basic concepts of second order nonlinear optical processes at interfaces3. Experimental part3.1. SFG experiments 3.2. Electrochemical cells4. Spectroscopic investigations of the electrochemical interface4.1. IR-visible sfg vibrational spectroscopy4.2. Time-resolved studies of vibrational dynamics4.3. Studies of the surface electronic properties 5. ConclusionReferences

Chapter 10 In situ Raman Spectroscopic Studies of Pyridine Adsorption on Different Transition-Metal Surfaces

Bin Ren, De-Yin Wu, Zhong-Qun Tian

1. Background2. Experimental2.1. Preparation of SERS-active electrode surface2.1.1. Electrochemical oxidation-reduction cycles (ORC) for preparing Fe, Co and Ni

electrodes2.1.2.Electrochemical ORC for preparing Pt and Pd electrodes

2.2 Raman Instrumentation2.2.1. Strategies to Increase the Detection Sensitivity2.2.2. Confocal Raman Microscope2.2.3. Optimization of the Experimental Setup3. Vibrational Properties of Pyridine3.1. Molecular structure and basic vibrational properties of free pyridine3.2. Vibrational properties of surface species3.3. Surface Selection Rules4. Experimental results4.1 Pyridine adsorption on Fe4.2 Pyridine adsorption on Co4.3 Pyridine adsorption on Ni4.4 Pyridine adsorption on Pd4.5 Pyridine adsorption on Pt5. Comparison of the experimental results of pyridine adsorption on different metal

surfaces5.1. The frequencies of the ν1 and ν6a modes for pyridine on different metal surfaces5.2. The relative intensity of the ν6a, ν9a and ν8a modes to the ν1 mode5.3. The relative intensity change of the ν12 (1037 cm-1) and ν18a (1067 cm-1) bands5.4. The intensity and frequency of the M-N band6. Theoretical calculation6.1. Vibrational frequency shift and binding interaction6.2. Interpretation of the relative intensity changes based on the surface enhanced non-

resonance Raman effect6.3. Charge-transfer enhancement7. Summary8. Acknowledgement9. References

Chapter 11 In-situ Surface X-ray Scattering and Infra-red Reflection Adsorption Spectroscopy of CO Chemisorption at the Electrochemical Interface

Christopher A. Lucasa and Nenad M. Markovicb

1. Introduction2. Instrumentation and methods of characterization2.1. Electrochemical measurements2.2. Surface x-ray scattering2.3. IRAS measurements3. CO adsorption onto Pt and Au3.1. High pressure UHV studies3.2. Structural studies in electrochemistry3.2.1. CO ordering on the Pt(111) surface3.2.2. Au(hkl) Surfaces3.3. Au versus Pt3.4. Structure sensitivity and reaction mechanism3.5. New challenges4. Summary

AcknowledgementsReferences

Chapter 12 Resonance elastic and inelastic X-ray Scattering Processes for in-situ Investigation of Electrochemical Interfaces

K.-C. Chang, A. Menzel, V. Komanicky, H. YouJ. Inukai, A. WieckowskiE.

1. Introduction2. X-ray interactions with atoms3. Experimental4. X-ray Fluorescence Studies4.1. Glancing-incidence x-ray fluorescence spectroscopy4.2. High-resolution fluorescence spectroscopy4.3. Fluorescence spectra from surfaces of nanoparticles5. Surface Anomalous Resonance X-ray Scattering and Polarization Dependence5.1. Platinum surface anodic oxidation5.2. Sulfate adsorbed on Pt(111) surface5.3. Carbon monoxide adsorbed on Pt(111)6. ConclusionAcknowledgementReferences

Chapter 13 In-situ ESR for studies of paramagnetic species on electrode surfaces and electron spins inside electrode materials

Lin Zhuang, Juntao Lu*

1. Introduction2. ESR principles

2.1. Electron spin resonance2.2. Hyperfine splitting 2.3. Line width2.4. Anisotropies of g-factor and hfs-constant2.5. Curie spins and Pauli spins2.6. Microwave penetration depth in conducting samples and Dyson line shape

3. Cell design for in-situ esr measurements4. Simultaneous electrochemical and esr measurements5. Paramagnetic species on electrode surfaces

5.1. Adsorbed radicals5.2. FeFc modified electrodes

6. Conducting polymers6.1. Simultaneous electrochemical-resistance-ESR measurements6.2. Variable temperature in-situ ESR measurements

7. Lithium intercalation into carbons7.1. The band model for lithium intercalation into carbons7.2. ESR determination of density of electronic states at Fermi level for lithiated carbons

7.3. Separating the band model from other intercalation mechanisms8. Summary remarks

AcknowledgementReferences

Chapter 14Coupling Interfacial Electrochemistry with Nuclear Magnetic Resonance Spectroscopy: An Electronic Perspective

YuYe Tong

1. Introduction2. Fundamentals

2.1 NMR Basics2.2 d–Band Structure, d–Band Center, and the Ef–LDOS2.3 CO–Metal Bonding: Electronic Band Perspectives of the 5 Forward and 2*

Back Donation3. Electronic Nature of Stark tuning effect

3.1 CN– on Polycrystalline Pt Surfaces3.2 CO on Pt Surfaces: A Correlation between 13C EC-NMR and IR3.3 CO on Polycrystalline Pd Surfaces

4. Electronic Effect of Alloying Pt surfaces: Ru vs. Pd5. Summary and Outlook

AcknowledgmentsReferences

Chapter 15From stepped single crystal surfaces to ordered bimetallicelectrodes: Impact on electro catalysis and adsorption

Helmut Baltruschat, Rainer Bußar, Siegfried Ernst and Fernando HernandezInstitute of Physical and Theoretical Chemistry, University of Bonn, Roemerstr. 164,D-53117 Bonn, Germany

Introduction

1. Fundamentals1.1. Definition of a Monolayer and the Surface Unit Cell for Stepped Surfaces 1.2 . Preparation of Stepped Surfaces of Gold and Platinum Single Crystals1.3. Characterization by cyclic voltammetry1.4. Anion adsorption and the point of zero charge2. METAL DEPOSITION AT STEPPED SURFACES 2.1. Upd at stepped surfaces and step decoration2.1.1. Step decoration 2.1.2. Influence of steps on the rate of upd2.2. Bulk metal deposition at stepped surfaces3. Differential Electrochemical Mass Spectrometry 3.1. Calibration of the mass spectrometer3.2. Cell designs for DEMS3.2.1. The one compartment thin layer cell3.2.2. Dual thin layer cell for continuous flow through of electrolyte3.3. Mass spectrometric cyclic voltammetry 4. ROLE OF STEPS IN ELECTROCATALYSIS 4.1. Rate of hydrogen evolution and oxygen reduction4.2. Influence of steps on coverage4.3. Hydrogenation of adsorbed small organic molecules4.3.1. Hydrogenation of adsorbed benzene and cyclohexene4.3.2. Hydrogenation of adsorbed ethene4.4. Oxidation of CO and small organic molecules4.4.1. Oxidation of carbon monoxide4.4.2. Adsorption and oxidation of methanol5. step decorated surfaces as model bimetallic surfaces (influence of step decoration on

adsorption): 5.1. The action of cocatalysts5.2. Step decoration for studying cocatalytic effects in CO and methanol oxidation5.2.1. Pt/Ru5.2.2. Methanol oxidation at Ru modified Pt single crystal electrodes5.2.3. The influence of Sn and Mo on CO oxidation5.3. Pd on regularly stepped Au surfaces5.3.1. Pd dissolution on Au(332)/Pd5.3.2. CO and benzene on Au(332)/Pd5.3.3. H2 evolution on Au(332)/Pd6. Concluding remarks

Reference

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