Nanomaterials and Their ApplicationsSeries Editor: M. MeyyappanCarbon Nanotubes: Reinforced Metal Matrix CompositesArvind Agarwal, Srinivasa Rao Bakshi, Debrupa LahiriInorganic Nanoparticles: Synthesis, Applications, and PerspectivesEdited by Claudia Altavilla, Enrico CilibertoNanorobotics: An IntroductionLixin Dong, Bradley J. NelsonGraphene: Synthesis and ApplicationsWonbong Choi, Jo-won LeeEdited byClaudia AltavillaEnrico CilibertoCRC Press is an imprint of theTaylor & Francis Group, an informa businessBoca Raton London New YorkCRC PressTaylor & Francis Group6000 Broken Sound Parkway NW, Suite 300Boca Raton, FL 33487-2742 2011 by Taylor and Francis Group, LLCCRC Press is an imprint of Taylor & Francis Group, an Informa businessNo claim to original U.S. Government worksPrinted in the United States of America on acid-free paper10 9 8 7 6 5 4 3 2 1International Standard Book Number-13: 978-1-4398-1762-9 (Ebook-PDF)Thisbookcontainsinformationobtainedfromauthenticandhighlyregardedsources.Reasonableeffortshavebeen made to publish reliable data and information, but the author and publisher cannot assume responsibility for the valid-ity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint.Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or uti-lized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopy-ing, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers.Forpermissiontophotocopyorusematerialelectronicallyfromthiswork,pleaseaccesswww.copyright.com(http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400.CCCisanot-for-profitorganizationthatprovideslicensesandregistrationforavarietyofusers.For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged.TrademarkNotice:Productorcorporatenamesmaybetrademarksorregisteredtrademarks,andareusedonlyfor identification and explanation without intent to infringe.Visit the Taylor & Francis Web site athttp://www.taylorandfrancis.comand the CRC Press Web site athttp://www.crcpress.com This book is dedicatedto my parents Ida and Nicolthe guiding lights,to my husband Giuseppe,the true love,and to my daughter Maridathe best reason to become a better personClaudia AltavillaTo my Family and to my MentorsEnrico CilibertoviiContentsForeword .........................................................................................................................................ixAcknowledgments .........................................................................................................................xiEditors ........................................................................................................................................... xiiiContributors ...................................................................................................................................xv1Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview .................................................................................................................................. 1Claudia Altavilla and Enrico Ciliberto2Inorganic Nanoparticles for the Conservation of Works of Art ................................. 17Piero Baglioni and Rodorico Giorgi3Magnetic Nanoparticle for Information Storage Applications ................................... 33Natalie A. Frey and Shouheng Sun4Inorganic Nanoparticles Gas Sensors .............................................................................. 69B.R. Mehta, V.N. Singh, and Manika Khanuja5Light-Emitting Devices Based on Direct Band Gap Semiconductor Nanoparticles ....................................................................................................................... 109Ekaterina Neshataeva, Tilmar Kmmell, and Gerd Bacher6Formation of Nanosized Aluminum and Its Applications in Condensed Phase Reactions ................................................................................................................... 133Jan A. Puszynski and Lori J. Groven7Nanoparticles for Fuel Cell Applications ...................................................................... 159Jin Luo, Bin Fang, Bridgid N. Wanjala, Peter N. Njoki, Rameshwori Loukrakpam, Jun Yin, Derrick Mott, Stephanie Lim, and Chuan-Jian Zhong8Inorganic Nanoparticles for Photovoltaic Applications ............................................. 185Elif Arici9Inorganic Nanoparticles and Rechargeable Batteries ................................................. 213Doron Aurbach and Ortal Haik 10Quantum Dots Designed for Biomedical Applications ............................................. 257Andrea Ragusa, Antonella Zacheo, Alessandra Aloisi, and Teresa Pellegrino 11Magnetic Nanoparticles for Drug Delivery .................................................................. 313Claudia Altavilla 12Nanoparticle Thermotherapy: A New Approach in Cancer Therapy ...................... 343Joerg Lehmann and Brita LehmannviiiContents 13Inorganic Particles against Reactive Oxygen Species for Sun Protective Products ................................................................................................................................ 355Wilson A. Lee and Miriam Raifailovich 14Innovative Inorganic Nanoparticles with Antibacterial Properties Attached to Textiles by Sonochemistry ........................................................................................... 367Nina Perkas, Aharon Gedanken, Eva Wehrschuetz-Sigl, Georg M. Guebitz, Ilana Perelshtein, and Guy Applerot 15Inorganic Nanoparticles for Environmental Remediation ........................................ 393Thomas B. Scott 16Inorganic Nanotubes and Fullerene-Like StructuresFrom Synthesis to Applications ......................................................................................................................... 441Maya Bar-Sadan and Reshef Tenne 17Inorganic Nanoparticles for Catalysis ............................................................................ 475Naoki Toshima 18Nanocatalysts: A New Dimension for Nanoparticles? ........................................... 511Paolo Ciambelli, Diana Sannino, and Maria SarnoIndex ............................................................................................................................................. 547ixForewordDevelopment, characterization, and exploitation of nanophase materials are all fundamen-tal to the anticipated nanotechnology revolution. In the last decade, research activities on carbon nanotubes, inorganic nanowires, quantum dots, and nanoparticles have increased exponentially,asevidencedbythelargenumberofpapersinpeer-reviewedjournals andconferencepresentationsacrosstheworld.Amongthevariousnanomaterials,inor-ganicnanoparticlesassumespecialimportancebecausetheyareeasierandcheaperto synthesizeinthelaboratoryandtomassproducethansomeothernanomaterialslike carbonnanotubes,forexample.Itisforthisreasonalsothattheycanbemorereadily integrated into applications. As synthesis, characterization, and application development using nanoparticles continues strongly, there is a need to capture the fundamentals and the current advances in a textbook for the beneftofresearchers, graduate students,and colleagues in various industries. This book by Drs. Claudia Altavilla and Enrico Ciliberto meetstheaboveneedadmirably.Anexcellentgroupofexpertshavebeenassembledto discuss the diverse applications of inorganic nanoparticles, which would otherwise have been impossible to cover by just one or two people.After an overview on material synthesis and general perspectives in Chapter 1, the book delves into myriad applications of nanoparticles. Chapter 2 covers a very interesting and uniqueapplicationintheconservationofart.Magneticmaterialshavefoundtheirway intomagneticstoragemedialongago,andChapter3coverstheuseofnanoparticlesin thisdomain.Oxidethinflms,especiallytinoxide,havebeentheconductingmediain commercial gas and vapor sensors, and Chapter 4 provides a discussion as to how their performancecanbeimprovedusingmetalandoxidenanoparticles.Solid-statelighting hasattractedattentionworldwideduetoitshighereffciencycomparedtoconventional lighting,butthecostsremainveryhigh.Advancesinmaterials,devicefabrication,and large-scale production are urgently required to reduce global energy demands. Chapter 5 discusses the advances in semiconductor nanoparticles for light-emitting devices.Besides lighting, other areas related to the energy sector, such as solar energy and energy storage devices (fuel cells, rechargeable batteries, etc.), can also beneft from the properties ofnanomaterials.ThesearecoveredinChapters7through9.Anotherindustrialsector thatislikelytofeeltheimpactofnanotechnologyisthebiomedicalfeld.Severalchap-ters are devoted to quantum dots for bioimaging, nanoparticle-based cancer therapy, drug delivery, antibacterial agents, and others. Last but not the least is the long-standing appli-cation in catalysis and the role of nanosized particles in this established feld.Ihopethereadersfndthistreatiseusefulasatextbookandresearchresource.Nora Konopka of CRC Press deserves praise for initiating the book series on nanomaterials.Meya MeyyappanMoffett Field, CaliforniaxiAcknowledgmentsWe thank all the contributors to this book for their extra effort in presenting state-of-the-art developments in their areas of expertise. This book would not have been possible without them. Additionally, we would like to acknowledge Dr. Meya Meyyappan for his trust and support in the realization of this project, and Nora Konopka and Kari Budyk of CRC Press for their constant technical support during all the stages of production. Tom Schott, who designed the cover of the book, is also heartily acknowledged. Finally, a special thanks to our families for their endless patience, which allowed us to spend time on the preparation of this book.xiiiEditorsDr. Claudia Altavilla graduated in chemistry (cum laude) in 2001 from the University of Catania, Italy. She received her PhD in chemistry in 2006 from the same university with adissertationonthesynthesisandcharacterizationofnanostructuredmaterialsassem-bledoninorganicsubstrates.SheworkedasavisitingscientistatLudwigMaximillians Universitat in Munich, Germany, with Professor Wolfgang Parak, and at the University of Florence,Italy,withProfessorDanteGatteschi,whereshewasinvolvedinthemagnetic characterization of nanoparticle monolayers on silicon substrates. Since 2005, she has been aprofessorofinorganicprotectiveandconsolidantmethodsinculturalheritageatthe University of Catania.Dr.Altavillascurrentresearchincludesthechemicalsynthesisofinorganicnanopar-ticles of ferrite, chalcogenite, and metals functionalized by different organic coatings for application in magnetic storage media, lubricants, magnetorheological fuids, and biomed-icine; and self-assembled monolayers of inorganic and organic nanostructures on different substrates and CVD synthesis of carbon nanotubes on silicon substrates using transition metal oxide nanoparticles as catalyst. She has published several papers and monographs. Sheisarefereeforinternationaljournalsonmaterialscienceandnanotechnologysuch asACSNano,ChemistryofMaterials,andtheJournalofMaterialChemistry.Currentlyshe is a research fellow in the Department of Chemical and Food Engineering, University of Salerno, Italy.Dr. Enrico Ciliberto is a full professor of inorganic chemistry at the University of Catania andthepresidentoftheCulturalHeritageTechnologiesFacultyattheUniversityof Syracuse, Italy. His research focuses on the chemistry of materials, including surface sci-ence and cultural heritage materials, both from an archaeometric and conservative point of view, and covers Minoan mortars in Crete, Michelangelos David in Florence, and Saint Marks Basilica in Venice. His current scientifc interest includes the application of nano-technologies for the conservation of works of art. He has also published over 100 scientifc papers.xvContributorsAlessandra AloisiNational Nanotechnology Laboratory of CNR-INFMItalian Institute of Technology Research UnitLecce, ItalyClaudia AltavillaDepartment of Chemical and Food EngineeringUniversity of SalernoFisciano, ItalyGuy ApplerotDepartment of ChemistryandKanbar Laboratory for NanomaterialsBar-Ilan University Center for Advanced Materials and NanotechnologyBar-Ilan UniversityRamat-Gan, IsraelElif AriciLinz Institute for Organic Solar CellsInstitute of Physical ChemistryJohannes Kepler UniversityLinz, AustriaDoron AurbachDepartment of ChemistryBar-Ilan UniversityRamat Gan, IsraelGerd BacherWerkstoffe der Elektrotechnik and Center for Nanointegration Duisburg-EssenUniversity Duisburg-EssenDuisburg, GermanyPiero BaglioniDepartment of Chemistry and Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande InterfaseUniversity of FlorenceSesto Fiorentino, ItalyMaya Bar-SadanInstitute of Solid State ResearchErnst Ruska-Centre for Microscopy and Spectroscopy with ElectronsResearch Centre JuelichJuelich, GermanyPaolo CiambelliDepartment of Chemical and Food EngineeringandCentre NANO_MATESUniversity of SalernoFisciano, ItalyEnrico CilibertoDipartimento di Scienze ChimicheUniversit di of CataniaCatania, ItalyBin FangDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkNatalie A. FreyDepartment of ChemistryBrown UniversityProvidence, Rhode IslandxviContributorsAharon GedankenDepartment of ChemistryandKanbar Laboratory for NanomaterialsBar-Ilan University Center for Advanced Materials and NanotechnologyBar-Ilan UniversityRamat-Gan, IsraelRodorico GiorgiDepartment of Chemistry and Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande InterfaseUniversity of FlorenceSesto Fiorentino, ItalyLori J. GrovenChemical and Biological Engineering DepartmentSouth Dakota School of Mines and TechnologyRapid City, South DakotaGeorg M. GuebitzInstitute of Environmental BiotechnologyGraz University of TechnologyGraz, AustriaOrtal HaikDepartment of ChemistryBar-Ilan UniversityRamat Gan, IsraelManika KhanujaThin Film LaboratoryDepartment of PhysicsIndian Institute of TechnologyNew Delhi, IndiaTilmar KmmellWerkstoffe der Elektrotechnik and Center for Nanointegration Duisburg-EssenUniversity Duisburg-EssenDuisburg, GermanyWilson A. LeeEstee Lauder Companies, Inc.Melville, New YorkBrita LehmannDepartment of RadiologySchool of MedicineUniversity of California DavisSacramento, CaliforniaJoerg LehmannDepartment of Radiation OncologySchool of MedicineUniversity of California DavisSacramento, CaliforniaStephanie LimDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkRameshwori LoukrakpamDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkJin LuoDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkB.R. MehtaThin Film LaboratoryDepartment of PhysicsIndian Institute of TechnologyNew Delhi, IndiaDerrick MottDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkEkaterina NeshataevaWerkstoffe der Elektrotechnik and Center for Nanointegration Duisburg-EssenUniversity Duisburg-EssenDuisburg, GermanyContributorsxviiPeter N. NjokiDepartment of ChemistryState University of New York BinghamtonBinghamton, New YorkTeresa PellegrinoNational Nanotechnology Laboratory of CNR-INFMItalian Institute of Technology Research UnitLecce, ItalyandIstituto Italiano di TecnologiaGenova, ItalyIlana PerelshteinDepartment of ChemistryandKanbar Laboratory for NanomaterialsBar-Ilan University Center for Advanced Materials and NanotechnologyBar-Ilan UniversityRamat-Gan, IsraelNina PerkasDepartment of ChemistryandKanbar Laboratory for NanomaterialsBar-Ilan University Center for Advanced Materials and NanotechnologyBar-Ilan UniversityRamat-Gan, IsraelJan A. PuszynskiChemical and Biological Engineering DepartmentSouth Dakota School of Mines and TechnologyRapid City, South DakotaMiriam RaifailovichMaterial Science and Engineering DepartmentStony Brook UniversityStony Brook, New YorkAndrea RagusaNational Nanotechnology Laboratory of CNR-INFMItalian Institute of Technology Research UnitLecce, ItalyDiana SanninoDepartment of Chemical and Food EngineeringandCentre for NANOMAterials and NanoTEchnologyUniversity of SalernoFisciano, ItalyMaria SarnoDepartment of Chemical and Food EngineeringandCentre for NANOMAterials and NanoTEchnologyUniversity of SalernoFisciano, ItalyThomas B. ScottInterface Analysis CentreUniversity of BristolBristol, United KingdomV.N. SinghThin Film LaboratoryDepartment of PhysicsIndian Institute of TechnologyNew Delhi, IndiaShouheng SunDepartment of ChemistryBrown UniversityProvidence, Rhode IslandReshef TenneMaterials and Interfaces DepartmentWeizmann Institue of ScienceRehovot, IsraelxviiiContributorsNaoki ToshimaDepartment of Applied ChemistryTokyo University of Science, YamaguchiSanyo-Onoda, JapanandCore Research for Evolutional Science and Technology (CREST)Japan Science and Technology AgencyKawaguchi, JapanBridgid N. WanjalaDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkEva Wehrschuetz-SiglInstitute of Environmental BiotechnologyGraz University of TechnologyGraz, AustriaJun YinDepartment of ChemistryState University of New York, BinghamtonBinghamton, New YorkAntonella ZacheoNational Nanotechnology Laboratory of CNR-INFMItalian Institute of Technology Research UnitLecce, ItalyChuan-Jian ZhongDepartment of ChemistryState University of New York, BinghamtonBinghamton, New York11Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn OverviewClaudia Altavilla and Enrico Ciliberto1.1IntroductionOver the last few years, a variety of inorganic nanomaterials such as nanoparticles, nanow-ires, and nanotubes have been created or modifed in order to obtain superior properties withgreaterfunctionalversatility.Theadventofnanoscalescienceandtechnologyhas stimulatedabigefforttodevelopnewstrategiesforthesynthesisofnanomaterialsofa controlledsizeandshape.Inparticular,nanoparticlesduetotheirsize,intherangeof 1100 nm, have been examined for their uses as tools for a new generation of technological devices. Moreover, due to their dimensions and shapes being similar to several biological structures (e.g., membrane cell genes, proteins, and viruses), they have been proposed for investigating biological processes as well as for sensing and treating diseases. Nowadays, thevolumeofstudiesdealingwiththesetopicsrepresentsoneofthemostimpressive phenomenoninallofscientifchistory.EvensoonlyoneNobelprize,sharedbythree scientists, has been awarded for the development of the studies in this feld in the last 20 years, in 1996, Robert F. Curl Jr., Sir Harold W. Kroto, and Richard E. Smalley were awarded for their discovery of fullerenes. In Figure 1.1, the number of scientifc articles and papers with reference to the themes of nanoparticles from 1996 until 2009 is reported: the expo-nentialtrendclearlyindicatesthatthescientifcandtechnologicalinterestiscontinuing to increase.Compared with the notable amount of scientifc and technological studies in this feld, only one Nobel prize could sound quite inadequate. One reason can probably be attributed to the fact that nanotechnologies are very old, even though several of the relationships between dimension and properties have only been clarifed in the nineteenth century. In fact, very few people know that even in the sixth century BC, nanotechnology was com-monly used in the Attic region (Greece). During the Archaic and Classical periods, roughly 620300BC,intheregionofAttica,dominatedbythecityofAthens,theproductionof CONTENTS1.1Introduction ............................................................................................................................ 11.2Properties of Nanoparticles .................................................................................................. 51.3Synthesis Strategies ............................................................................................................... 61.4Applications ............................................................................................................................ 81.5Conclusion ............................................................................................................................ 13References ....................................................................................................................................... 142Inorganic Nanoparticles: Synthesis, Applications, and Perspectivesdecorated vases reached an extraordinary artistic level due to the development of a highly original fring technique that obtained a magnifcent black/red dichromatism, the secret of Greek vases (Figure 1.2) (Boardman 1991).Thereasonwhyadeepblackcolorformed onthevasesurfacewasdiscoveredonlya few years ago. During the fring process, spinel-like nanoparticles formed inside a glassy layer, which is a few microns thick (Maniatis et al. 1992). In Figure 1.3, a secondary electron microscope(SEM)imageofsubmicronparticlesinsideaglossylayerofasixthcentury BC Greek vase is reported. The magnetite particles, looking whitish in the backscattered mode, show different sizes (100300 nm) and different shapes. A skillful alternation of the 1996199719981999200020012002200320042005200620072008200905,00010,00015,00020,00025,0000.35%1.02%1.41%1.76%2.45%2.73%3.41%4.78%6.49%9.08%11.46%14.33%18.28%>100,000 recordsRecord countPublication year21.78%FIGURE 1.1Temporal evolution in the number of scientifc papers on nanoparticles published from 1996 to 2009. More than 100,000 records were found and more than 54% of the articles have been published in the last 3 years. (Data from ISI Web of Knowledge.)FIGURE 1.2Attic black fgure krater, sixth century BC. (Courtesy of Prof. Enrico Ciliberto.)Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview3oxidizing and reduction processes, induced by either opening or closing the oven vents, stimulated the formation of black magnetite nanoparticles (Hemelrijk 1991).Inaddition,lusterceramicdecorationshavebeenrevealedbytransmissionelectron microscopy (TEM) to have been ancient nanostructured metallic thin flms made by man. Considering this type of decoration in the context of cultural heritage, it is a remarkable discoveryinthehistoryoftechnology,becausenanocrystalflmshavebeenproduced empirically since medieval times (Borgia et al. 2002; Padovani et al. 2003). Luster is a type of ceramic decoration, which results in a beautiful metallic shine and colored iridescence on the surface of the ceramic object. The earliest luster was probably made in Iraq in the early ninth century AD on tin-glazed ceramics. However, luster technology spread from the Middle East to Persia, Egypt, Spain, and Italy, and its splendid production continued in the centuries that followed through to the present day. In TEM, luster layers appear with a homogeneous surface microstructure formed by small quasispherical clusters, embedded in an amorphous glassy matrix (Figure 1.4).The total thickness of this structure is 200500 nm. An initial outer layer is formed by the biggest clusters, which have a diameter of about 50 nm. The diameter of the next layer, with smaller inner clusters, is 520 nm. With respect to the composition of these clusters, transmission electron microscopy (TEM) ftted with energy dispersive x-ray spectroscopy (EDS) analyses indicate that the nanoclusters are particles of pure copper and silver (Perez-Arantegui and Larrea 2003).In addition, red glasses that are very ancient are colored due to the presence of nanopar-ticles. In fact, excavations at Qantir, on the Nile Delta, have given insight into the organi-zation and development of an industrial estate in Ramesside, Egypt. In founding the new capitalofEgypt,Piramesses,duringthenineteenthdynasty,ahugebronze-castingfac-tory was built, accompanied by a range of other, nonmetallic high-temperature industries. 1 m* Mag = 26.76 K XWD = 8 mmSignal A = QBSDEHT = 15.00 kVDate : 20 Jun 2008Time : 12:58:08FIGURE 1.3Back scattered electron image of submicron magnetite particles inside the black glossy layer of the vase reported in Figure 1.2. (Courtesy of Prof. Enrico Ciliberto.)4Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesBesides, an abundant production of faience implements, coated with copper-colored glazes, and the manufacturing of Egyptian blue, the coloration of large quantities of red glass also playedamajorrole.Theproductionofglassisattestedbynumerouscrucibles,mostly with adhering traces of red glass. While evidence of glass working by artisans is absent, there are indications that the production of both raw glass and glass coloring took place. The nature and complexity of high-temperature industrial debris found at Qantir suggest a highly specialized organization of labor within a framework of shared technologies and skills of closely controlled temperatures and redox conditions. This cross-craft workshop pattern further reveals a signifcant level of intracraft specialization as well as the spatial separation of glass making, coloring, and fnally working in the LateBronzeAge Egypt (Rehrenetal.1998).Wenowknowthattheredcolorisduetometalnanoparticlescon-tained in the glass network. The use of metal nanoparticles dispersed in an optically clear matrix by potters and glassmakers from the Bronze Age up to the present time has been reviewedbyColombanfromasolid-statechemistryandmaterialsciencepointofview. Thenature ofmetal(gold, silver,orcopper)and the importanceof some otherelements (Fe, Sn, Sb, and Bi) added to control metal reduction in the glass in relation to the fring atmosphere (combined reducing oxidizing sequences and role of hydrogen and water) are considered in the light of ancient treatises and recent analyses using advanced techniques (TEM,extendedx-rayabsorptionfnestructure(EXAFS),etc.)aswellasclassicalmeth-ods (optical microscopy, UVvisible absorption). The different types of color production, by absorption/refection (red and yellow) or diffraction (iridescence), as well as the rela-tionship between nanostructures (metal particle dispersion and layer stacking) and luster color have been also discussed. It has also been shown that Raman scattering is a very use-ful technique in order to study the local glass structure around the metal particles as well as detect incomplete metal reduction or residues tracing the preparation route; therefore, making it possible to differentiate between genuine artifacts and fakes (Colomban 2009).In all the aforementioned cases, old technology surpassed the scientifc interpretation of the related phenomena and, today, experimental experience remains the basis of modern 30 nmFIGURE 1.4TEM image of a smalt from an Italian Renaissance Luster Majolica. Copper nanoparticles show diameters rang-ing from 7 to 10 nm. (Courtesy of Prof. Bruno Brunetti.)Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview5progress, even if thermodynamic and quantum mechanics have already explained many of the properties of nanoscale materials (Lafait 2006; Cavalcante et al. 2009).1.2Properties of NanoparticlesOnthenanoscale,materialsbehaveverydifferentlycomparedtolargerscales.Infact, nanoparticlesoftenhaveuniquephysicalandchemicalproperties.Forexample,the electronic, optical, and chemical properties of nanoparticles may be very different from those of each component in the bulk. By increasing the surface area with respect to the volumeofaparticle,acorrespondingincreasingofimportanceofthebehaviorofthe surface atoms can be observed, and a modifcation of the properties of the particle itself as well as of its interaction with the surrounding environment take place. Moreover, in ordertobecomesmallenough,atransitionfromclassicalphysicsbehaviortoaquan-tum mechanic, one describes the particle that can now be viewed as an artifcial atom, an object that possesses discrete electronic states, similar to naturally occurring atoms. Anelectroninanartifcialatomthatcanbedescribedbyaquantumwave-function that issimilartothe oneused for an electron in asingle atom, even though its energy is spread coherentlyoverthe lattice of atomicnuclei. Asthe sizeofacrystal decreases to the nanometer regime, the size of the particle begins to modify the properties of the crystal. The electronic structure is altered by the continuous electronic bands to discrete or quantized electronic levels. As a result, the continuous optical transitions between the electronicbandsbecomediscreteandthepropertiesofthenanomaterialbecomesize-dependent. Therefore, optical, thermal, and electrical properties of the particles become dependent on their sizes and shapes. These properties have been recently reviewed by Burda et al. (2005).However, some of the properties of the nanoparticles might not be predicted by under-standing the increasing infuence of surface atoms or quantum effect. For instance, it has beenshownthatsiliconnanoparticlesintherangeof20100 nmaresuperhardinthe 3050 GParangeafterworkhardening(Gerberichetal.2003).Thenanospherehardness fallsbetweentheconventionalhardnessofsapphiresanddiamonds,whichareamong thehardestknownmaterials.Theextremelysmalldimensionsofnanobuildingblocks have created diffcult challenges to many existing instruments, methodologies, and even theories.Themethodsthathavebeendevelopedandusedformeasuringthemechani-cal properties of isolated individual nanobuilding blocks include uniaxial tensile loading usingananomanipulationstage,in-situcompressionofnanoparticlesandnanopillars, mechanical/electric-feld-inducedresonance,atomicforcemicroscopy(AFM)bending, andnanoindentation(Uchicetal.2004).Thesemethodscertainlyrepresentimportant instruments that help scientists in designing low-cost superhard materials from nanoscale building blocks.Whilenanoparticlesdisplaypropertiesthatdifferfromthoseofbulksamplesofthe samematerial,groupsofnanoparticlescanhavecollectivepropertiesthataredifferent to those displayed by individual nanoparticles and bulk samples. For realizing versatile functions, an assembly of nanoparticles in regular patterns on surfaces and at interfaces is required (Altavilla 2007). Assembling nanoparticles generates new nanostructures, which have unforeseen collective, intrinsic physical properties. These properties can be exploited for multipurpose applications in nanoelectronics, spintronics, sensors, etc. (Nie et al. 2010).6Inorganic Nanoparticles: Synthesis, Applications, and Perspectives1.3Synthesis StrategiesThere are a wide variety of techniques for producing nanoparticles. These essentially fall intothreecategories:physicalmethods,chemicalsyntheses,andmechanicalprocesses such as milling.Amongthephysicalmethods,pulsedlaserablationhasbeendemonstratedtobea powerfulandversatiletechniqueforpreparinghigh-puritynanoparticlesornanoflms (Longstreth-Spoor et al. 2008). In general, the targets used for the preparation of nanopar-ticlesorflmsbylaserablationarebulksizes,andthelasersareeitherexcimer,pulsed yttriumaluminiumgarnet(YAG),orfemtosecondlasers.Thequalityandsizesofthe nanoparticlespreparedbythesesystemsarecontrolledbyoptimizingeitherthelaser parameters or ambient-gas pressure. The main advantage of laser ablation is the congruent (stoichiometric) material transport above the threshold fuence, which is used for depos-itingcomplexcompoundssuchashigh-Tcsuperconductors(Kangetal.2006).Inaddi-tion, high-melting-point materials (e.g., C, W, and refractory ceramics) are easily deposited (Ullmann et al. 2002; Chen et al. 2004). Passivated -Fe nanoparticles can also be prepared at atmospheric pressure by pulsed laser ablation of an Fe wire and a bulk Fe target (Wang et al. 2009). Other physical methods used in preparing nanoparticles belong to the category of vapor condensation. This approach is used to prepare metallic and metal oxide ceramic nanoparticles. It involves the evaporation of a solid metal followed by rapid condensation to form the fnal nanostructured material. Different methods can be adopted to produce metal vapors. An inert gas is also used to inhibit oxidizing phenomena but in some cases, oxygen atmosphere is used to make metal oxide nanoparticles. The main advantage of this approach is low contamination levels. Final particle size is controlled by the variation of temperature, fux parameters, and gas environment (Swihart 2003).Themostwidelyusedchemicalsynthesisessentiallyconsistsofgrowingnanoparti-clesinaliquidmediummadeupofvariousreactants.Thechemicalgrowthofbulkor nanometer-sized materials inevitably involves the process of precipitation of a solid phase from a solution. For a particular solvent, there is a certain solubility for a solute, whereby addition of any excess solute will result in the precipitation and formation of nanocrystals. Thus, in the case of nanoparticle formation, for nucleation to occur, the solution must be supersaturatedeitherbydirectlydissolvingthesoluteathighertemperaturesandthen cooling to low temperatures or by adding the necessary reactants to produce a supersatu-ratedsolutionduringthereaction.Theprecipitationprocessthenbasicallyconsistsofa nucleation step followed by particle growth stages (Peng et al. 1998). For a homogeneous nucleation that occurs in the absence of a solid interface, the phenomenon can be described by the overall free energy change (G) because the supersaturated solutions are not stable fromathermodynamicpointofview.Ithasbeen demonstratedthatGdependsonthe saturation ratio of the solution as well as the radius of nuclei formed (Burda et al. 2005).G shows a maximum critical value of the radius (rc) that corresponds to a critical size of the particle (see Figure 1.5). This maximum free energy is the activation energy for nucle-ation. Nuclei larger than the critical size will further decrease their free energy for growth and form stable nuclei that grow to form particles.Thegrowthprocessofnanocrystalscanoccurintwodifferentways,focusingand defocusing, depending on the concentration of the solution. A critical size exists at any given concentration. At a high concentration, the critical size is small so that all the par-ticles grow. In this situation, smaller particles, slightly larger than the critical size, have a high free energy driving force and grow faster than the larger ones. As a result, the size Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview7distributioncanbefocuseddowntoonethatisnearlymonodisperse.Ifthemonomer concentration is below a critical threshold, small nanocrystals are depleted as larger ones grow and the size distribution broadens, or defocuses (Yin and Alivisatos 2005).The preparation of nearly monodisperse spherical particles can be achieved by stopping the reaction while it is still in the focusing regime, with a large concentration of monomer still present (Peng et al. 1998). In general, it is desirable for nucleation to be separated in time from the growth step in order to obtain relatively monodisperse samples. This means that nucleation must occur on a short timescale. This may be achieved by rapidly injecting suitable precursors into the solvent at high temperatures to generate transient supersatura-tion in solutions and induce a nucleation burst. In addition to this kind of growth, where soluble species deposit on the solid surface, particles can grow by aggregation with other particles, and this is called secondary growth. The rate of particle growth by aggregation is much larger than by molecular addition. Finally, the control over size, size distribution, and secondary growth becomes a more challenging problem in such dimensional regimes. In the synthesis of colloidal nanoparticles, the key strategy stands within the use of spe-cifcmolecules,whichactasterminatingorstabilizingagents,ensuringaslowgrowth rate,preventinginterparticleagglomeration,andconferringstabilityaswellasfurther processabilitytotheresultingnanoparticles.Thesemoleculesareoftenchosenamong various classes of surfactants. Surfactants are molecules composed of a polar head group andoneormorehydrocarbonchainswithahydrophobicnature.Themostcommonly used in colloidal syntheses include alkyl thiols, amines, carboxylic and phosphonic acids, phosphines, phosphine oxides, phosphates, phosphonates, as well as various coordinating solvents (Cozzoli et al. 2006).Animportantstepinthegenerationofcolloidalinorganicnanoparticlesistheiden-tifcationofsuitableprecursormoleculessuchasmetalcomplexesandorganometallic compounds.Theprecursorsneedtorapidlydecomposeorreactattherequiredgrowth temperature to yield reactive atomic or molecular species (often called monomers), which then cause nanocrystal nucleation and growth (Stuczynski et al. 1989; Steigerwald 1994). In this sense,these chemicalmethodsoperatingin solutionscan be relatedtothe metal organic chemical vapor deposition where volatile precursors in vapor phase react and/or decompose on the substrate surface to produce a desired deposit at much higher growth GrcrFIGURE 1.5Free energy G as a function of the radius of particle; rc, critical radius size.8Inorganic Nanoparticles: Synthesis, Applications, and Perspectivestemperatures (Sun et al. 2004; Aptiga et al. 2007; Creighton et al. 2008). The two approaches share many features including similar basic chemical reactions involved.Along with the mechanical techniques used to prepare nanoparticles, a method that has received a great deal of interest from the industrial world is bead milling. The particle size achieved from a bead mill is a direct function of the size of the beads used for the grind-ing process. The average particle size that can be quickly achieved in a bead mill is about 1/1000thesizeofthegrindingmedia.Thesmallestbeadsizeregularlyusedonacom-mercial basis is 200300 m. The applications of this media are primarily in the pigment manufacturing and ink industry for the fne grinding and dispersion of pigments such as phthalocyanine blue and green as well as carbon black. The uses for these inks are in the ink jet market, textile inks, etc. (Czekai 1996).Sonochemistryischaracterizedbybothmechanicalandchemicalproperties.Infact, sonochemical methods refer to chemical reactions that are induced by acoustic cavitations. In organic solvents, the high-temperature conditions generated during acoustic cavitations havebeenusedtosynthesizemetalandothernanomaterials.Inwater,avarietyofpri-mary and secondary radicals are generated during acoustic cavitations that can be used for a series of redox reactionsin aqueous solutions.Moreover, it has been demonstrated how the size, size distribution, and, to some extent, the shape of metal nanoparticles may be controlled by the sonochemical preparation method (Muthupandian 2008).1.4ApplicationsThe goal of this book is to describe the most important applications of nanoparticles.In Chapter 2, Piero Baglioni and Rodorico Giorgi introduce the use of nanoparticles in thefeldofculturalheritageconservation.Thecontributionofsciencetotheconserva-tionofculturalheritagehasradicallyincreasedoverthelastyears,manythankstothe advancements in the knowledge of the physicochemical composition and properties of the materials constituting the works of art (Ciliberto 2000).Nanoparticlesofcalciumhydroxidegiveaconsistentimprovementovertheclassical application of a calcium hydroxide solution. In fact, the use of Ca(OH)2 dispersions over-comethelimitationduetothelowsolubilityinwater,alcoholsarelessaggressivethan watertowardfragilemuralpaintings,andthequickcarbonationofhydroxidesgivesa strong consolidation effect. Calcium and magnesium hydroxide as a nonaqueous disper-sion also give excellent results for the treatment of cellulose-based materials. These pref-erably require waterless solvents and need an alkaline reserve to protect the object from further degradation due to pollution or internal acid production as a consequence of the natural aging of the materials. Humble particles of calcium or magnesium hydroxide give excellent results and ensure high physicochemical compatibility with the substrates that grant the durability of the treatment and long-lasting protection of the works of art. With illustrative examples on the consolidation of wall paintings and deacidifcation of books andwood,thiscontributionalsoreportsonsomerecentcasestudies,highlightingthe improvedperformancesofnanoparticlesandnanocontainers(micelles,microemulsion, nanogels, etc.) in respect to traditional conservation methodologies.Theuse ofmagneticnanoparticlesfor aninformation storage applicationis discussed by Natalie A. Frey and Shouheng Sun in Chapter 3. High-quality monodisperse magnetic nanoparticleswithhighcoercivitycanbemadefromvariouschemicalsynthesisroutes Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview9andprovideawayaroundthesuperparamagneticlimitthatiscurrentlyencroaching uponthegranularmediathatisusedinharddiskdrivestoday.Consideringthatsyn-thesized nanoparticles are usually superparamagnetic, some novel approaches have been used to anneal the particles at high temperature, facilitating the face centered cube (fcc) to face centered tetragonal (fct) phase transition in FePt nanoparticles while keeping the par-ticles from sintering and allowing the particles to be dispersed again in organic solvents. In order to increase packing density to maximize areal density for media, the shapes can becontrolledand self-assemblycan beemployedtocontrol interparticlespacing,which inturnprovidescontrolovermagneticinteractions.Evenhigheranisotropicrareearth-transitionmetalnanoparticlesarebeingsynthesized,thoughthechallengesassociated withtheirsynthesesaresignifcant.Inthecaseof SmCo5,nanoscalepowderswith high coercivity have been made after reductively annealing core-shell structures. More needs to be done to protect these particles from sintering during the annealing process and the issue of chemical stability needs to be addressed. The results presented paint a promising picture for the future of magnetic nanoparticles in recording technology.Gas sensor technologies have received a signifcant boost from nanoparticles. There is alargevolume ofdata ontheuse ofmetaloxidenanoparticles and nanoparticlelayers for gas sensor applications. Lack of accurate and reliable information about nanoparticle size, size distribution, metal additive, composition, and confguration makes the analysis ofthisdataachallengingtask,butB.R.Mehtaetal.describethecurrentstateofartof thistopicinChapter4.Duetothepercentageofatomsonthesurfaceincreasingwith thedecreaseinparticlesizeasthesurface-to-volumeratioisinverselyproportionalto radius, nanoparticles will offer a large surface area for gas adsorption, which is always thefrststepinthegas-sensingmechanism.However,foramoredetailedandclearer understanding of the dependence of gas sensing properties on nanoparticle size and the nature of the metal additive, it is important to use synthesis methods suitable for yield-ingwell-defnednanoparticlesizesandcompositeconfguration.Someofthecurrent researchdirectionsincludetheuseofsynthesismethodsforwell-defnednanoparticle sizes,areliableandscaleelectroniccharacterizationofnanoparticlesusingconducting AFM and scanning tunneling microscopy on gas exposure, as well as the fabrication of nanowirenanoparticle or decorated nanowire composites.Nowadays,thedemandforlow-costlightemittersishigh,coveringawiderangeof different applications in the advertising and giveaway industry, low-cost indicators, and displaysforconsumerelectronics,mobilephones,toys,andmanymore.InChapter5, Ekaterina Neshataeva et al. discuss light-emitting devices (LEDs) based on semiconductor nanoparticles.VersatileimplementationsofnanocrystalsinLEDsareexpectedtocom-bine the robustness and effciency of conventional semiconductor LEDs with low-cost pro-cessingtechniquesusedforlarge-areaorganicLEDs.Thisfascinatingresearchfeldnot only requires the development of innovative fabrication and processing techniques using nanoparticles but also opens a path toward novel applications and devices. In the chapter, anoverviewofvariousdeviceconceptsandtechnicalapproachesisgivenfocusingon thedevices,wherenanoparticlesareusedasactivematerials.Bothdirectandalternat-ing current-driven light emitters are also discussed, covering the time span from early to recent developments in the feld.The formation of nanosize aluminum and its applications in condensed phase reaction has been reviewed by Jan A. Puszynski and Lori J. Groven in Chapter 6. They clearly indi-cate that the use of nanosize reactants in condensed phase exothermic reactions leads to a signifcant increase in the energy release rate. Such high-energy release rates, not com-monly observed between oxidizer and fuel particles, make these nanoenergetic systems 10Inorganic Nanoparticles: Synthesis, Applications, and Perspectivessuitablecandidatesforenvironmentallybenignmacro-andmicroinitiatorsaswellas energeticcomponentsofmicrothrustersandotherapplicationsrequiringfastcombus-tion front velocities. The recent developments in the formation of aluminum nanopow-ders indicate that high-temperature methods seem to be more suitable for scale-up than low-temperature wet chemistry synthesis routes. The mechanical reduction of aluminum particlesizeseemstobeanotherpromisingapproachformakinglargerquantitiesof reactive aluminum nanopowders.Fuel cells using hydrogen represent an important form of tomorrows energy due to it not only being an effcient fuel but also environmentally clean. The auto industry, which relies onoil-fuelledcars,isperhapsthebiggestdrivingforcebehindthemassiveinvestment in fuel cell development. Jin Luo et al. have reviewed this interesting area of research in Chapter 7. In particular, they claim that the molecular encapsulation approach to the syn-thesis and processing of bimetallic/trimetallic nanoparticles is effective in producing alloy nanoparticles in the 25 nm regime with controllable composition and carbon-supported catalystsforfuelcellreactions.Thisapproachdiffersfromothertraditionalpreparation approaches of supported catalysts in the abilities to control the nanoscale size, multimetal-lic composition, phase properties, and surface properties. As demonstrated by the bime-tallic AuPt alloy nanoparticle catalysts, synergistic activity is possible in which Au atoms surroundingPtprovideeffectivesitesforthereactionadsorbatesintheelectrocatalytic reaction. The fact that this bimetallic nanoparticle system displays a unique single-phase property different from the miscibility gap of its bulk-scale counterpart serves as an impor-tantindicationoftheoperationofnanoscalephenomenainthecatalysts,whichcanbe further exploited for the design and preparation of the nanostructured bimetallic catalysts for fuel cells. Trimetallic nanoparticle catalysts have displayed enhanced electrocatalytic activity. For carbon-supported ternary PtVFe and PtNiFe nanoparticle catalysts, the size, composition, and loading of the nanoparticles on carbon support have been shown to be controllable, as well as processible by controlled thermal treatment and calcination, which can be optimized in order to achieve the effective shell removal and alloying of the ternary catalysts.Themeasurementsoftheintrinsickineticactivitiesofthecatalyststowardan oxygen reduction reaction have shown high electrocatalytic activities, and the trimetallic PtVFenanoparticlecatalystspreparedbythenanoengineeredsynthesisandprocessing methods have exhibited a much better performance in proton exchange membrane (PEM) fuelcellcathodethanthecommercialPtcatalyst.Italsobecomesclearthatthesynthe-sis and processing approach to the preparation of nanoparticle catalysts is promising for delivering much higher catalyst utilization than those of conventional methods, which has important implications on the improved design of fuel cell cathode catalysts.Solarcells,devicesthatconverttheenergyofsunlightdirectlyintoelectricity,based on organicinorganic hybrid blends arediscussedby Elif Arici-Bogner in Chapter8. He describesthecurrentstateofartinorganicinorganichybridsolarcellsthatusenano-crystalline inorganic materials in two different functions: as anodes and inorganic dyes in dye-sensitized solar cells as well as in bulk heterojunction solar cells. The basic parameters of photovoltaic devices and their characterization, synthesis aspects of inorganic nanopar-ticles investigated as active materials in solar cells as well as the material characterization methods, and the new developments for integration of inorganic nanoparticles in photo-voltaic devices are discussed in this chapter.Therelationshipbetweennanoparticlesandrechargeablebatteriesisdescribedin Chapter 9 by Doron Aurbach and Ortal Haik. This chapter deals with the possible use of nanomaterials in devices for energy storage and conversion, with an emphasis on inorganic species (e.g., alloys transition metal oxides and sulfdes and carbon nanotubes). Four types Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesAn Overview11of devices are discussed and classifed: batteries (primary and secondary), fuel cells, super electricdouble-layercapacitors,andphotovoltaiccellswiththemainfocusonrecharge-able batteries. For fuel cells, the main interest in nanomaterials relates to the catalysts. For low temperatures,hydrogen/oxygen, and alcohol/oxygen (direct) fuel cells, the catalysts are metallic particles comprising mostly platinum and its alloys. The authors mention dye-sensitized photovoltaic cells in which the anode material is semiconducting titanium oxide wheretherequiredhighsurfaceareaisreachedthroughtheuseofnanoparticles.For super capacitors, whose energy storage mechanism is based on electrostatic interactions, nanostructured carbonaceous materials may provide the necessary high surface area and hencehighcapacity.Forrechargeablebatteries,theuseofnanomaterialsmayenablea high capability rate, because of the short length for solid-state diffusion (which is usually the determining step rate for intercalation materials). However, nanomaterials may have high surface reactivity, which can be detrimental for Li ion battery systems, in which there isno thermodynamicstability between mostoftherelevant electrodematerialsandthe nonaqueous polar electrolyte solutions. There are some cases in which the use of nanoma-terials is crucial: LiMPO4 olivine cathode materials, silicon- and tin-based anode materials, as well as anodes based on conversion reactions (e.g., MO + Li = Li2O + M). Nano-alumina and silica may be a desirable component in polymeric electrolytes because of the existence of ionic conductance mechanisms based on the interactions between Li ions and surface oxygens of the nanoparticles. The various battery components are classifed and discussed in connection with the possible use of nanomaterials.Nanobiotechnology, the combination of nanotechnology with biology, allows the use of nanotools and nanodevices to interact with, detect, and alter biological processes at a cel-lular and molecular level. A. Ragusa et al. in Chapter 10 describe the use of semiconductor quantumdotsforbiomedicalapplications.Semiconductornanocrystals,alsoknownas quantum dots (QDs), representan emerging class of inorganic fuorescent markers.Due totheirinorganicnature,theyofferrevolutionaryfuorescenceperformanceincluding narrowandsymmetricalemissionspectraforlowinterchanneloverlap,broadadsorp-tionspectraandextremelybrightemittingcolorsforsimplesingle-excitationmulticolor analysis,long-termphotostabilityforlive-cellimaging,anddynamicsstudies.Sincethe frst proof of the concept of the application of QDs as fuorescent probe on living cells in 1998, numerous groups have demonstrated the signifcant potential of such a tool in biol-ogy. In this chapter, the authors provide an overview of the exploitation of QDs in different biological applications ranging from biosensoring to labeling and imaging, both on in vitro models and in vivo animal studies. They also consider their use in photodynamic therapy and multimodal imaging techniquesfelds of research that have only recently been cre-ated but are already attracting a lot of attention.Aninterestingstrategy,withimmensepotentiality,thatcanbeusedtoremotelycon-trolthedeliveryofadrugorgeneistheuseofmagneticnanoparticlesmanipulatedby an external magnetic feld. After a brief description of the physical principles underlying some current biomedical applications of nanoparticles (superparamagnetism, hyperther-mia, and manipulation of magnetic nanoparticles inside blood vessel), Claudia Altavilla, in Chapter 11, reviews the most important wet chemistry strategies to design, synthesize, protect, and functionalize magnetic nanoparticles and/or multifunctional systems as drug delivery carrier. Some of the most explicative and signifcant recent studies on the applica-tion of these smart drug delivery systems in vivo and in vitro are fnally reported.Thermotherapy,elevationoftissuetemperaturetoabove40C41C,haslongbeen described and researched for cancer therapy. The addition of magnetic nanoparticles was introducedinthehopeforamorefocusedandhomogenousdistributioninthecancer 12Inorganic Nanoparticles: Synthesis, Applications, and Perspectivestissuewhilesparinghealthytissue.Theprincipleofnanoparticlethermotherapy,dis-cussed by Joerg Lehmann and Brita Lehmann in Chapter 12, is the excitement of magnetic nanoparticles, which have been brought in close proximity to cancer cells through the use of an alternating magnetic feld. Heat is produced through the transfer of the energy of the alternating magnetic feld via magnetic hysteresis losses and Brownian relaxation losses. Thereisevidencethatthetechnologyiscapableofprovidingaseriousblowtocancer, possibly even complete remission. However, in relation to this point, only mice have been cured. The methods of nanoparticle delivery to cancer cells and creating the alternating magnetic feld are reviewed in this chapter, as well as the properties of the nanoparticles. Referenceismadetoanimalstudiesandinitialclinicaltrials.Thistrulyinterdisciplin-aryfeldinvolvingchemists,biologists,physicians,andphysicistsisverymuchunder development.InChapter13,WilsonA.LeeandMiriamRaifailovichdescribetheuseofinorganic particles against reactive oxygen species for sun protection products. The chemical graft-ingofantioxidantmoleculesandanionicpolymerencapsulatedinahydrophobicpoly-merdirectlyontoTiO2particlesurfaceisfoundtomitigatephotocatalyticdegradation, enabling highly effective fltering against UV radiation. The coating consists of a densely graftedpolymer,ananionicpolymer,andafreeradicalscavenger.Theadditionofthe coated particles prevents scission and even possible hydrolysis of the DNA after exposure to UVA, UVB, and even UVC radiation.Metaloxidenanoparticlescanbeuniformlydepositedontothesurfaceofdifferent kindsoftextilesbyasonochemicalmethodinordertoachieveantibacterialproperties. The topic is discussed by Nina Perkas et al. in Chapter 14. The coating can be performed byasimple,effcient,one-stepprocedureusingenvironmentallyfriendlyreagents.The physical and chemical analyses demonstrated that nanocrystals of 2030 nm in size are fnely dispersed onto fabric surfaces without any signifcant damage to the structure of the yarn. The mechanism of nanooxide formation and adhesion to the textile is also discussed. It is based on the local melting of the substrate due to the high rate and temperature of the nanoparticles thrown at the solid surface by sonochemical microjets. The strong adhesion of the metal nanooxides to the substrate has been demonstrated in terms of the absence of the leaching of the nanoparticles into the washing solution. The performance of fabrics coatedwithalowcontentofnanooxides( Li2O + M0 (Villevieille et al. 2007; Chen et al. 2009). The condition for a reversible behavior of these reactions is the use of nanopowder of MO. Figure 9.10 illus-tratesthemaindifferencesbetweenconversionandintercalationreactionsinwhichLi ions are involved.Conversion reactions of thetype presented in Figure 9.10 were demonstrated not only withtransitionmetaloxidesbutalsowithmetalfuorides(AmatucciandPereira2007) and magnesium hydride (Oumellal et al. 2009). Most of them exhibit a reversible capacity between400and700 mAh/g,twicehigherthatthatofthecommonlyusedLigraphite anodes.Theirpotentialprofleisslopingbetween21.5 Vand0 Vvs.Li/Li+.Thesetrac-tionsinvolvecomplicatedinteractionswithsolutionspecies,especiallyatthelow-volt-age domain. They suffer from pronounced hysteresis: there may be a difference of more than0.5 Vbetweenthechargeanddischargepotentials.Thereareincreasingnumbers of reports inthe literature about these kinds of reactionsdue to the scientifc interest in them. However,the opinionof the authors of thischapteristhat these reactions arenot reallypractical,becausealltypesofrelevantsolutionspeciesarethermodynamically very unstable with the nano powders at the low potentials in which they interact with Li ions and undergo conversion reactions. Hence, it is hard to expect from electrodes based onthesereactionsthenecessarystabilityinrealbatterysystems,especiallyatelevated temperatures.Anotherpossibleapplicationfornano-materialsinLi-ionbatteriesrelatestotheso-called intermetallic anodes. One of the alternatives for the problematic Li metal anode are Li alloys. Li can alloy reversibly with such Al, Mg, Sn, and Si at high capacities (e.g., around 900 and 4000 mA h/g for Li4.4Sn and Li4.4Si, respectively, compared to 372 mA h/g for Ligraphite, LiC6) (Anani and Huggins 1992). However, these alloying processes are accom-panied by very pronounced volume changes. For instance, full alloying of Sn and Si with lithium leads to 300% volume increase. Such volume changes lead to stresses and strains that crack and disintegrate the active mass upon repeated lithiationdelithiation cycling. Moreover, these volume changes interfere very badly with the anodes passivation, which Inorganic Nanoparticles and Rechargeable Batteries237is mandatory for their operation in rechargeable Li batteries. At the low potentials of these Lialloyingprocesses,alltherelevantpolaraprotic,electrolytesolutionsusedinLibat-teries, are reduced on the electrodes and hence they are unstable. The apparent stability ofmost ofaproticLisalt solutionswith Li,LiC,orLiM(any metal) anodesisbecause the reduction of most of aprotic Li salt solutions forms as products insoluble Li salts and oligomericspeciesthatprecipitateontheelectrodesaspassivatingsurfaceflms.These surface flms when reaching a certain thickness block electrons transfer and, hence, avoid continuous reduction of the solutions but allow Li ions transport through them. Thus, if anode materials are not stable and cannot develop steady passivation, they cannot be used in rechargeable batteries. The most important approach to improve the reversibility of Li alloying with elements such as tin and silicon (the most important candidates as alternative high capacity anode materials to graphite, for Li-ion batteries) in aprotic Li salt solutions is the use of nanoparticles. Upon lithiation of nano-powders of tin or silicon, the stresses and strains related to the volume changes are better relieved (Winter and Besenhard 1999). The pronounced surface reactivity of nanoparticles of LiSn or LiSi alloys can be handled by the use of appropriate binders and additives in solutions which enhance formation of stable passivating surface flms (Li et al. 2007a; Hochgatterer et al. 2008).In addition to the use of nanoparticles, the reversibility of the LiSn or LiSi alloying pro-cesses can be improved by the use of multicomponent systems. For instance, the new com-mercial, Nexelion advanced Li-ion batteries from Sony, contains anodes that comprise Sn, carbon, and Co composites (Wolfenstine et al. 2006). The main anode process is of course lithiationoftin,whilethelattertwoelementsactasstressesandstrainrelieverswhich keeptheactivemasswellintegrateduponcycling,byabsorbingthevolumechanges duetoLiSnalloying.TherearemanyreportsonLiSnCandLiSiCcompositesas improved anode materials. Especially interesting are the development of SiC composites InsertionConversionMMDischargeDischargeChargeChargeMX2eeeeLiMX2Li2X + M3050 3050 MX + 2e + 2Li+M + Li2XMX2 + e + Li+Li+Li+Li+Li++ LiMX2Li XMXMX2MXFIGURE 9.10(See color insert following page 302.) A schematic illustration of insertion (top) and conversion (bottom) reac-tionsinwhichLiionsareinvolved.(ReprintedfromArmand,M.andTarascon,J.-M.,Nature,451,652,2008. With permission.)238Inorganic Nanoparticles: Synthesis, Applications, and Perspectiveswith core-shell structure (Kim and Cho 2008). There are also many reports on ternary and quaternary LiSn(Si)M1(M2) composites as potentially important anode materials. With all of these composite materials, there is an advantage to the use of nanoparticles (Vaughey et al. 2001).9.5.2.3Positive ElectrodesIngeneral,thepositiveelectrodeshavetobeelectrochemicallyactiveatrelativelyhigh redoxpotentials.The cathode materialsforLi-ionbatteriesare lithiatedtransitionmetal oxidesandsulfdes(LixMOy,LixMSy),andLiMPO4olivinecompounds(M = Fe,Mn,Co). These materials are the source of lithium in Li-ion battery systems.Afrstprocessinthesesystemsisalwayscharging,inwhichthecathodematerialis delithiated and the lithium ions are intercalated in the negative electrode (the mass bal-ance has to take into account the irreversible capacity of the negative electrodes, part of whichisinvolvedintheestablishmentoftheirpassivationbysurfaceflmsformation). Most of the lithiated transition metal oxides relevant as cathode materials for Li-ion bat-teries are reactive with alkyl carbonates/LiPF6 solutions and develop surface flms. Hence, their electrochemical behavior and stability are largely infuenced by their surface chem-istry(Aurbachetal.1998a,b;Aurbach1999).Thereby,mostofLixMOycathodematerials cannot be used as nanoparticles because they become covered by too thick surface layers that impedeLi ionstransport. It may be possible to use nano LixMOy cathode materials when they are covered by carbon layers (Odani et al. 2006) or by other protecting surface layers that can act as a buffer zone that protect the active mass from detrimental interac-tions with solution species (e.g., acidic moieties) (Cho et al. 2000; Gnanaraj et al. 2003; Park et al. 2008).About a decade ago,LiFePO4 olivinewasintroducedasa promising cathode material for rechargeable Li batteries (Padhi et al. 1997). Since then, many hundreds of publications appeared in the literature on this material and it even became commercial. The electron and Li-ion transport properties of this material are very poor. However, it was discovered thatbytheuseofnanoparticlesandcoatingwithverythinconductinglayers(likecar-bon), it is possible to overcome the poor kinetics of Li insertion, deinsertion into/from this material, and to make it a very fast cathode material. A recent, most promising achieve-ment is the performance of the LiFePO4 cathode material described in Figure 9.11 (Kang and Ceder 2009).The challenge with these olivine materials is to develop practical LiMnPO4 and LiCoPO4 as practical cathode materials because their redox potentials are 4.1 and 4.8 V vs. Li, respec-tively, a gain of 0.6 and 1.3 V, respectively, compared to LiFePO4, yet at the same theoretical capacity (close to 170 mA h/g).Figure9.12presentssomerecentdatarelatedtoLiMnPO4thatdemonstratetheprom-isingpotentialofthisfamilyofcompoundstoserveassuperbcathodematerialsin advancedLi-ionbatteries(Marthaetal.2009).Thisfgureshowshigh-resolutiontrans-mission electron microscopy (TEM) images of the active mass, which comprises carbon-coatednanoparticles;thegaininpotentialofLiMnPO4comparedtoLiFePO4;andsome voltageproflesmeasuredupondischargeofcompositeLiMnPO4cathodesatdifferent rates (Martha et al. 2009). It should be emphasized that further modifcation of this cathode material can considerably improve its rate capability.Upper right chart: comparison of the voltage profles of LiMnPO4 and LiFePO4. Lower rightchart:voltageproflesmeasuredduringgalvanostatic(constantcurrent)discharge processes at different rates. 5C mean discharging the electrodes capacity within 12 min.Inorganic Nanoparticles and Rechargeable Batteries2394.03.5Voltage (V)3.02.52.00 20 40 60 80Capacity (mA h/g)100 12050C 2C140 160 1802C10C20C30C40C50C500 nmFIGURE 9.11Presentation of an ultrafast LiFePO4 cathode. Left: Voltage profles obtained upon discharging this material at different rates. Note that a fate of 50C means discharging most of the capacity of the cathode material within around 1.2 min. Right: A scanning electron microscopy (SEM) image of the LiFePO4 nanoparticles. (Reprinted from Kang, B. and Ceder, G., Nature, 458, 190, 2009. With permission.)Carbon layer~15 nmLiMnPO4nano-particle~30 nmLiMnPO4 nano-particled-spacing0.34 nmd-spacing0.27 nmd-spacing0.34 nmCarbon layer2.50 25 50 75Discharge capacity (mA h/g)100 125 150C/10C/20Operating voltage = 2.7 V 4.4 VT = 30C5C 2C C C/2 C/50 25 50 75Discharge capacity (mA h/g)1000.7 VAt C/20 rate and 30CLiMnPO4LiFePO4125 175 1503.03.54.04.52.53.0Cell voltage (V)Cell voltage (V)3.54.04.55 nm20 nmFIGURE 9.12Presentation of some data related to LiMnPO4 electrodes. Left: High resolution images of the active mass-carbon coatednanoparticlesofLiMnPO4.Upperright:ComparisonofthevoltageproflesofLiMnPO4andLiFePO4. Lower right: Voltage profles measured during galvanostatic (constant current) discharge processes at different rates. 5C mean discharging the electrodes capacity within 12 min.240Inorganic Nanoparticles: Synthesis, Applications, and PerspectivesThesecathodesbasedontheLiMPO4olivinecompoundsmarkthemostsuccessful application of nano-materials in rechargeable batteries. The nanosize means short enough lengthforthesolid-statediffusionofLiionsthatmaybearate-determiningstepforLi insertion processes into inorganic hosts. It is the opinion of the authors of this chapter that it is possible to use LiMPO4 compounds as nano-powder in composite cathodes for Li-ion batteries (in contrast to the case of LixMOy compounds), because the oxygen atoms of these compounds that are bound to P5+ cations are not too nucleophilic or basic and, hence, there surface reactions, even when the active mass have high specifc surface area, are very mod-erateanddonotformisolatingsurfaceflmsthatinterferebadlywiththeinter-particle electricalcontactandleadtohighimpedance(asisthecaseforelectrodescomprising nanoparticles of lithiated transition metal oxides (Talyossef et al. 2007)).9.5.2.4Electrolyte SystemsThere are fve major electrolyte systems relevant to batteries and related devices:1.Liquidsolutionsbasedonwell-dissolvedelectrolytesinpolarsolvents,with goodionseparation.Theseliquidsystemsincludeaqueoussolutionsinwhich wateristhesolvent,ornonaqueoussystemsinwhichthesolventsareusually polar aprotic (as dealt with later). Aqueous solutions are used in several important systems,includingZnMnO2,Znair, NiCd, NiMH,andleadacid.Exceptfor the last system, in which the electrolyte is H2SO4, for all the other batteries in the listthesolutionsarealkaline,usingKOHastheelectrolyte.Nonaqueouselec-trolyte solutions are relevant mostly to Li and Li-ion batteries and related devel-opments, e.g., rechargeable magnesium batteries. The most important families of solvents are ethers, esters, and alkyl carbonates. There may be some use of nitriles and sulfones as well (miscellaneous).2.Liquidsystemsbasedonionicliquids(ILs)(Armandetal.2009),i.e.,molten salts.Herethesolventsareionicmedia,therebyprovidingtheelectrolyticfunc-tion. ILs are now being intensively studied in connection with Li and Mg batteries because they are stable, nonfammable, and may provide very wide electrochemi-cal windows (and thus can be suitable for high-voltage batteries).3.Gel electrolytes: In these systems, the active electrolyte systems consist of solvents and salts, contained in an inert polymeric matrix. Such systems can be treated as liquid electrolyte solutions, since their ionic conductivity is similar in the order of 103 s cm1, and the interfacial properties of the electrodes are determined by their surface reactions with the solvents and the salt anions (Stephan 2006).4.Polymeric electrolytes: Here the solvent system consists of polymers, derivatives of polyethers. Polyethers can dissolve Li salts because of the strong interaction of Liionswiththeoxygenatomsthatenabletheseparationofcharges.Theroom-temperature ionic conductivity of a polyether/Li salt system is lower by 2.5 orders of magnitude, compared to that of liquid solutions (106105 vs. 103102 s cm1). Thus,polymeric,solvent-freeelectrolytesareexpectedtoworkatelevatedtem-peratures>60C.Thereactivityofthesesystemstowardlithiumismuchlower than that of liquid systems. However, they are not inert toward lithium because Li metal attacks ether linkages. Impressive innovative efforts are underway to syn-thesizederivativesofpolyethersthatfacilitatechargeseparationandtransport. Critical efforts in this feld relate to increasing the low-temperature conductivity Inorganic Nanoparticles and Rechargeable Batteries241and the transference number of Li ions (which should lower the detrimental con-centration gradients) (Stephan and Nahm 2006).5.Ceramicelectrolytes:Solidssuchas-alumina,Li3PO4,andboron-basedglass can transport active metal ions (e.g., Li+, Na+). Intensive work is underway on solid conductorsforprotonandoxygenionsforhigh-temperaturefuelcells.Mostof theceramicelectrolytesareplannedtoworkathightemperatures,hundredsof degrees centigrade. However, the fabrication of microbatteries in which the elec-trolyte systems are thin flms of solids such as Li3PO4 enable operation at ambient temperatures (Duclot and Souquet 2001; Zhang et al. 2005).We can classify the following major differences between liquid (items 1 through 3 above) and solid (items 4 and 5 above) electrolyte systems:1.Thetemperaturerangeofinterestisquitedifferent.Forliquidelectrolytesolu-tions,the highestrelevanttemperaturesare40C. The range for polymeric electrolytes (gels and solvent-free systems) may be room temperature up to 60C. The temperature range of interest for ceramic electrolytes may be from ambient temperature up to 1000C.2.The ion transportmechanismsarepronouncedly differentwhen comparing liq-uid and solid electrolytes. Hence, while the same electrochemical methods can be applied forcharacterization,theirinterpretationis completelydifferent forsolid and liquid electrolyte systems.3.Theinterfacialchargetransferisalsodifferentintermsofcontactpoints.While the liquidelectrode interfaces are continuous and do not contain voids, the contact between electrodes and solid electrolyte matrices may not be continuous. Hence, not the entire electrode surface in contact with the solid electrolyte is really active.4.Phenomenarelatedtotheelectrodessurfacechemistry,suchascorrosion,pas-sivation, and surface flm formation, are much less pronounced with solid electro-lytes than with liquid electrolyte solutions. This is due to the much lower expected reactivity of solid electrolytes toward all electrode materials, as compared to that ofliquidsystems.Hence,theelectrochemicalresponsefromelectrodeliquidor electrodesolid interfaces is quite different and relates to different types of charge transfer processes.5.The engineering aspects are, of course, much different. When liquid solutions are used, a solid separator isneeded as a spacer between theelectrodes (and which is usually a porous polymeric flm soaked with the electrolyte solution). In solid state systems, the solid electrolyte can also serve as the inter-electrode spacer.We can distinguish among four classes of solid electrolytes for batteries:1.Gelelectrolytesolidpolymericmatricesthataresoakedwithliquidelectrolyte solutions: the solvent dissolves the electrolyte (Osaka et al. 1997).2.Solvent-free polymeric electrolyte: the polymeric chains can dissolve Li salts. This is relevant mostly to poly-ethers and their derivatives (Sun and Kerr 2006).3.Compositescomprisingpolymerceramicmaterialsandelectrolytesystems:in thesesystems,theceramicmaterialsthataremostpreferredarenanopowders, e.g., SiO2, Al2O3, dispersed within the polymeric matrices and provide additional conductingmechanismsofionsviamigrationontheirhighsurfacearea.The 242Inorganic Nanoparticles: Synthesis, Applications, and Perspectivesuse of such composite systems is relevant to both gel- and solvent-free polymeric matrices (Wachtler et al. 2004).4.Ceramic materials and solid-state electrolytes (Shahi et al. 1983).Composite systems comprising polymers, salt, and ceramic powders (item 3 above) are very promising electrolytes because it is possible to achieve high ionic conductivity despite the solid structure. For these composite matrices, nanoparticles of ceramic materials such as silica and alumina are critical components. The surface oxygen atoms of the particles are involved in a main conducting mechanism of Li ions in the matrix and the nanosize oftheparticlesensuresthenecessaryhighsurfaceareaforthisconductingmechanism (Peled et al. 1995; Tominaga et al. 2005; Bhattacharyya et al. 2006).9.5.2.5Separators and MembranesTheelectrodesinbatterieshavetobeseparatedinordertopreventshortcircuit,i.e., mechanicalseparation,andalsotopreventtheexchangeofions/compoundsthatinter-fere badly with the desired electrochemical reactions of the electrodes, i.e., chemical sep-aration.Theroleofseparators/membranesinbatteriesiscritical,anditaffectsinternal resistance, rates, stability, cycle life, temperature range, and safety features. In most of the battery systems, the active mass is contained, stable in solid electrodes, and the same ions in solution react with both electrodes. This is the case for all alkaline stationary batteries, leadacidsystems,andnonaqueousLi,Li-ion,andMgbatteries.Insuchcases,whatare neededbetweentheelectrodesareseparatorsthatmaintainthemechanicalstabilityof the systems. In NiCd, NiMH, and LA systems, the aqueous solutions are involved in theelectrochemicalreactions.Thus,theyhavetobethickenoughtocontaintheappro-priateamountofsolution.Inthecaseofthebatteriesinwhichthesolutionservesonly asanionconductor,theseparatorshouldbeasthinaspossible,porous,butyetstrong enoughtomaintainthemechanicalandelectricalseparationbetweentworoughcom-positeelectrodes.Forinstance,porouspolypropyleneorpolyethyleneflms(afewtens of microns thick) are used for Li-ion batteries. Although the main components in separa-tors for batteries are of course polymeric matrices, there is a great advantage for the use of composite separators that contain ceramic nanoparticles. In Li metal batteries, a main problem is thedendrite formationduringcharging(Lidepositionprocesses). Separators containing ceramic nanoparticles may be useful for preventing dendrite growth and pen-etration through the separator. The design of composite separators is a special art. There is a compromise between the degree of porosity and mechanical strength. In addition, the wettability of the pores is important. Ceramic particles embedded in the porous polymeric matricesofseparatorsmayfacilitatetheirwettingbyallkindofsolutionsforbatteries application (both aqueous and nonaqueous) (Arora and Zhang 2004).9.6On the Synthesis of Nano-Materials for Rechargeable Li-Ion BatteriesThere are many thousands of reports in the literature on the synthesis of nano-materials for batteries. Hence, it is impossible to cover this matter in a single chapter (or even in a single book). We describe below a few selected syntheses modes that produce nano-mate-rials that are relevant to Li batteries.Inorganic Nanoparticles and Rechargeable Batteries2439.6.1Self-Combustion ReactionsThese are simple methods for synthesizing nanosized lithiated mixed metal oxides. This methodinvolvesexothermicreactionbetweenmetalnitratesintherightstoichiometry andsomeinorganicororganicreducingcompounds(fuel)andhavebeendevelopedin recent years (Verneker 1986; Dhas and Patil 1993; Patil et al. 2002; Gopukumar et al. 2004; Hwang et al. 2006).The main advantages are the good mixing between the atoms and the formation of nano size clusters, whose further calcination produces nanoparticles of mixed metal oxides. The heat needed for the synthesis of these metal oxides is provided by the exothermic reaction between the fuel and the oxidizers, namely, the precursors that are the metal nitrates.Forexample,theself-combustionreaction(SCR)ofthelayeredLiNixMnyCozO2com-pounds, using sucrose as the fuel can be written as follows (Haik et al. 2009):LiNO3 + Ni(NO3)2 + Mn(NO3)2 + Co(NO3)2 + C12H22O11 LiNixMnyCozO2 + CO2 + H2O + NO SCRs can be carried out in glass or ceramic vessels, in which the starting solutions are initially heated to 150C. At this temperature, ignition of the SCR takes place leading to spontaneous exothermal reactions that involve fame and gas evolution. The fnal parti-cles size (from nano to micro) can be well controlled by two parameters: further heating (up to 1000C) in air and heating duration. It should be noted that as the calcination tem-peratures are higher, the particles thus formed are bigger and more ordered, possessing smoother facets. However, calcinations at too high temperatures (e.g. >950C) may lead tooxygenevolutionand,hence,totheformationofoxygen-defcientLiNixMnyCozO2w products.Fortunately,itispossibletoreoxidizesuchspeciesbyfurtherannealingin oxygen-containing atmosphere at lower temperatures (e.g., 1500 m2/gE-modulus 1000 GPaInorganic Nanoparticles and Rechargeable Batteries249The application of these unique materials in devices for energy storage and conversion is in its frst stage. However, it is possible to draw several promising directions for the use of CNT in batteries and EDL capacitors.In general, CNT can be used as both active electrodes materials and as supporting com-ponents in composite electrodes.MWCNTs can serve as Li insertion anode material in Li-ion batteries (Endo et al. 2004; Sheem et al. 2006). The high electrical conductivity, the very high aspect ratio, and the con-sequent high specifc surface area make them suitable electrodes material for super (EDL) capacitors(Jungetal.2004;Wenetal.2006).Thesamepropertiesplustheirimpressive mechanical strength make them very desirable components in composite electrodes of all kinds of batteries, which can enhance remarkably the mechanical and electrical integrity of electrodes for rechargeable batteries (Odani et al. 2003; Endo et al. 2008). The possibil-ityofmodifyingCNTbygrafting,thusattachingtothemfunctionalgroupsandpoly-meric species (Tasis et al. 2006; Piran et al. 2009), make them even more attractive to use in batteries. In recent years, we see attempts to develop new organic cathode materials for rechargeable Li batteries that may replace the inorganic host materials which are currently inuse.TheseincludepolymerswithSSbonds(Dengetal.2006;Lietal.2007a,b)and compounds with multi C=O double bonds (Chen et al. 2008) that can be reversibly reduced and interact with Li ions at high enough potentials. Most of the organic cathode materi-als presented to date suffer from severe kinetic limitations, due to poor electron transfer to compounds which are electrical insulators. Functionalizing CNT, which can conducts electrons very well, by oxygenated or sulfur containing groups, may create superb, high-capacityandfast,organic,grincathodematerialsforrechargeableLibatteries.These possible approaches can be considered as a major challenge for nano-materials in connec-tion with energy storage and conversion.ReferencesAifantis, K.E., Dempsey, J.P., and Hackney, S.A. 2005. 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