Editedby PierrePichat PhotocatalysisandWater Purification RelatedTitles Duke,M.,Zhao,D.,Semiat,R.(eds.) Ganoulis,J. Functional Nanostructured RiskAnalysis ofWaterPollution Materials andMembranesfor 2009 WaterTreatment ISBN:978-3-527-32173-5 2013 Parmon,V.N.,Vorontsov,A.V., ISBN:978-3-527-32987-8 Kozlov,D.,Smirniotis,P. Cecen,F.,Aktas,O¨. Photocatalysis Activated CarbonforWaterand Catalysts,KineticsandReactors Wastewater Treatment 2008 IntegrationofAdsorptionandBiological ISBN:978-3-527-31784-4 Treatment Wiesmann,U.,Choi,I.S., 2012 Dombrowski,E.-M. ISBN:978-3-527-32471-2 Biological Wastewater Gottschalk,C.,Libra,J.A.,Saupe,A. Treatment Ozonation ofWaterandWaste Fundamentals,Microbiology,Industrial ProcessIntegration Water APracticalGuidetoUnderstandingOzone 2007 anditsApplications ISBN:978-3-527-31219-1 2010 Turovskiy,I.S.,Mathai,P.K. ISBN:978-3-527-31962-6 WastewaterSludge Processing 2006 ISBN:978-0-471-70054-8 Edited by Pierre Pichat Photocatalysis and Water Purification From Fundamentals to Recent Applications TheEditors AllbookspublishedbyWiley-VCHare carefullyproduced.Nevertheless,authors, editors,andpublisherdonotwarrantthe Prof.Dr.PierrePichat informationcontainedinthesebooks, CNRS,EcoleCentraledeLyon includingthisbook,tobefreeoferrors. (STMS),Photocatalyseet Readersareadvisedtokeepinmindthat Environnement statements,data,illustrations,procedural 69134EcullyCEDEX detailsorotheritemsmayinadvertentlybe France inaccurate. LibraryofCongressCardNo.:appliedfor BritishLibraryCataloguing-in-Publication Data Acataloguerecordforthisbookisavailable fromtheBritishLibrary. Bibliographicinformationpublishedbythe DeutscheNationalbibliothek TheDeutscheNationalbibliothek liststhispublicationintheDeutsche Nationalbibliografie;detailedbibliographic dataareavailableontheInternetat <http://dnb.d-nb.de>. 2013Wiley-VCHVerlagGmbH&Co. KGaA,Boschstr.12,69469Weinheim, Germany Allrightsreserved(includingthoseof translationintootherlanguages).Nopart ofthisbookmaybereproducedinany form–byphotoprinting,microfilm,orany othermeans–nortransmittedortranslated intoamachinelanguagewithoutwritten permissionfromthepublishers.Registered names,trademarks,etc.usedinthisbook, evenwhennotspecificallymarkedassuch, arenottobeconsideredunprotectedbylaw. PrintISBN: 978-3-527-33187-1 ePDFISBN: 978-3-527-64542-8 ePubISBN: 978-3-527-64541-1 mobiISBN: 978-3-527-64543-5 oBookISBN: 978-3-527-64540-4 Materialsforsustainableenergyand development(Print)ISSN: 2194-7813 Materialsforsustainableenergyand development(Internet)ISSN: 2194-7821 CoverDesign LaserwordsPrivateLimited, Chennai,India Typesetting LaserwordsPrivateLimited, Chennai,India PrintingandBinding MarkonoPrintMedia PteLtd,Singapore V Editorial Board Members of the Advisory Board of the ‘‘Materials for Sustainable Energy and Development’’Series ProfessorHuimingCheng ProfessorCalumDrummond ProfessorMorinobuEndo ProfessorMichaelGra¨tzel ProfessorKevinKendall ProfessorKatsumiKaneko ProfessorCanLi ProfessorArthurNozik ProfessorDetlevSto¨ver ProfessorFerdiSchu¨th ProfessorRalphYang VII Contents SeriesEditorPreface XVII Preface XIX AbouttheSeriesEditor XXIII AbouttheVolumeEditor XXV ListofContributors XXVII PartI Fundamentals:ActiveSpecies,Mechanisms,Reaction Pathways 1 1 IdentificationandRolesoftheActiveSpeciesGeneratedonVarious Photocatalysts 3 YoshioNosakaandAtsukoY.Nosaka 1.1 KeySpeciesinPhotocatalyticReactions 3 1.2 TrappedElectronandHole 6 •− 1.3 SuperoxideRadicalandHydrogenPeroxide(O andH O ) 7 2 2 2 • 1.4 HydroxylRadical(OH ) 9 1.5 SingletMolecularOxygen(1O ) 12 2 1.6 ReactionMechanismsforBareTiO 15 2 1.7 ReactionMechanismsofVisible-Light-ResponsivePhotocatalysts 17 1.8 Conclusion 20 References 21 2 PhotocatalyticReactionPathways–EffectsofMolecularStructure, Catalyst,andWavelength 25 WilliamS.Jenks 2.1 Introduction 25 2.2 MethodsforPathwayDetermination 27 2.3 PrototypicalOxidativeReactivityinPhotocatalyticDegradations 29 2.3.1 OxidationofArenesandtheImportanceofAdsorption 30 2.3.1.1 HydroxylationandtheSourceofOxygen 30 2.3.1.2 Ring-OpeningReactions 32 VIII Contents 2.3.1.3 IndicatorsofSETversusHydroxylChemistryinAromatic Systems 32 2.3.2 CarboxylicAcids 35 2.3.3 AlcoholFragmentationandOxidation 36 2.3.4 OxidationofAlkylSubstituents 37 2.3.5 ApparentHydrolysisReactions 38 2.3.6 Sulfur-BearingCompounds 39 2.4 PrototypicalReductiveReactivityinPhotocatalyticDegradations 39 2.5 TheUseofOrganicMoleculesasTestProbesforNext-Generation Photocatalysts 41 2.6 ModifiedCatalysts:Wavelength-DependentChemistryofOrganic Probes 42 2.7 Conclusions 44 References 45 3 PhotocatalyticMechanismsandReactionPathwaysDrawnfromKinetic andProbeMolecules 53 ClaudioMinero,ValterMaurino,andDavideVione 3.1 ThePhotocatalyicRate 53 3.1.1 OtherKineticModels 55 3.1.2 Substrate-MediatedRecombination 57 3.2 SurfaceSpeciation 60 3.2.1 DifferentCommercialCatalysts 60 3.2.2 SurfaceManipulation 61 3.2.3 CrystalFaces 62 3.2.4 SurfaceTrapsforHoles 64 3.3 MultisiteKineticModel 65 3.4 Conclusion 68 References 68 PartII ImprovingthePhotocatalyticEfficacy 73 4 DesignandDevelopmentofActiveTitaniaandRelated Photocatalysts 75 BunshoOhtani 4.1 Introduction–aThermodynamicAspectofPhotocatalysis 75 4.2 PhotocatalyticActivity:Reexamination 77 4.3 DesignofActivePhotocatalysts 78 4.4 AConventionalKineticsinPhotocatalysis:First-OrderKinetics 79 4.5 AConventionalKineticsinPhotocatalysis:Langmuir–Hinshelwood Mechanism 80 4.6 TopicsandProblemsRelatedtoParticleSizeofPhotocatalysts 82 4.7 RecombinationofaPhotoexcitedElectronandaPositiveHole 85 4.8 EvaluationofCrystallinityasaPropertyAffectingPhotocatalytic Activity 86 Contents IX 4.9 ElectronTrapsasaPossibleCandidateofaRecombinationCenter 87 4.10 DonorLevels–aMeaningofn-TypeSemiconductor 89 4.11 DependenceofPhotocatalyticActivitiesonPhysicalandStructural Properties 90 4.11.1 CorrelationbetweenPhysicalPropertiesandPhotocatalytic Activities 90 4.11.2 StatisticalAnalysisofCorrelationbetweenPhysicalPropertiesand PhotocatalyticActivities–aTrial 92 4.11.3 CommonFeaturesofTitaniaParticleswithHigherPhotocatalytic Activity 94 4.11.4 HighlyActiveMesoscopicAnataseParticlesofPolyhedralShape 95 4.12 SynergeticEffect 96 4.13 Doping 97 4.14 ConclusiveRemarks 98 Acknowledgments 99 References 99 5 ModifiedPhotocatalysts 103 NuritShaham-WaldmannandYaronPaz 5.1 WhyModifying? 103 5.2 FormsofModification 104 5.3 ModifiedPhysicochemicalProperties 106 5.3.1 CrystallinityandPhaseStability 106 5.3.2 SurfaceMorphology,SurfaceArea,andAdsorption 107 5.3.3 AdsorptionofOxygen 111 5.3.4 ConcentrationofSurfaceOH 111 5.3.5 Specificity 112 5.3.5.1 TiO SurfaceOvercoating 115 2 5.3.5.2 CompositesComprisedofTiO andMetallicNanoislands 116 2 5.3.5.3 DopingwithMetalIonsandOxides 116 5.3.5.4 Utilizingthe‘‘AdsorbandShuttle’’MechanismtoObtain Specificity 117 5.3.5.5 MesoporousMaterials 119 5.3.5.6 MolecularImprinting 120 5.3.6 Products’Control 122 5.3.6.1 SurfaceModificationbyMolecularImprinting 123 5.3.6.2 CompositesComprisedofTiO andMetallicNanoislands 124 2 5.3.6.3 DopingwithMetalIons 124 5.3.6.4 NonmetallicComposite 125 5.3.6.5 TiO MorphologyandCrystallinePhase 125 2 5.3.7 ReducingDeactivation 125 5.3.8 RecombinationRatesandChargeSeparation 126 5.3.8.1 StructureModification 127 5.3.8.2 Composites–MetalIslands 127 5.3.8.3 CompositesComprisingCarbonaceousMaterials 128 X Contents 5.3.8.4 CompositesComposedofTiO andNonoxideSemiconductors 128 2 5.3.8.5 CompositesComposedofTiO andOtherOxides 129 2 5.3.8.6 DopingwithMetals 131 5.3.8.7 DopingwithNonmetals 132 5.3.9 VisibleLightActivity 132 5.3.10 Charging–Discharging 132 5.3.11 MassTransfer 133 5.3.12 FacilitatingPhotocatalysisinDeaeratedSuspensions 134 Summary 134 References 134 6 ImmobilizationofaSemiconductorPhotocatalystonSolidSupports: Methods,Materials,andApplications 145 DidierRobert,Vale´rieKeller,andNicolasKeller 6.1 Introduction 145 6.2 ImmobilizationTechniques 147 6.3 Supports 152 6.3.1 Packed-BedPhotocatalyticMaterials 153 6.3.2 MonolithicPhotocatalyticMaterials 155 6.3.3 OpticalFibers 164 6.4 LaboratoryandIndustrialApplicationsofSupported Photocatalysts 168 6.5 Conclusion 171 References 172 7 WastewaterTreatmentUsingHighlyFunctionalImmobilizedTiO 2 Thin-FilmPhotocatalysts 179 MasayaMatsuoka,TakashiToyao,YuHoriuchi,MasatoTakeuchi,and MasakazuAnpo 7.1 Introduction 179 7.2 ApplicationofaCascadeFalling-FilmPhotoreactor(CFFP)forthe RemediationofPollutedWaterandAirunderSolarLight Irradiation 180 7.3 ApplicationofTiO Thin-Film-CoatedFibersfortheRemediationof 2 PollutedWater 184 7.4 ApplicationofTiO ThinFilmforPhotofuelCells(PFC) 186 2 7.5 PreparationofVisible-Light-ResponsiveTiO ThinFilmsandTheir 2 ApplicationtotheRemediationofPollutedWater 187 7.5.1 Visible-Light-ResponsiveTiO ThinFilmsPreparedbyCationor 2 AnionDoping 188 7.5.2 Visible-Light-ResponsiveTiO ThinFilmsPreparedbytheMagnetron 2 SputteringDepositionMethod 190 7.6 Conclusions 195 References 195 Contents XI 8 SensitizationofTitaniaSemiconductor:APromisingStrategytoUtilize VisibleLight 199 ZhaohuiWang,ChunchengChen,WanhongMa,andJincaiZhao 8.1 Introduction 199 8.2 PrincipleofPhotosensitization 200 8.3 DyeSensitization 201 8.3.1 FundamentalsofDyeSensitization 202 8.3.1.1 GeometryandElectronicStructureofInterface 202 8.3.1.2 Excited-StateRedoxPropertiesofDyes 203 8.3.1.3 ElectronTransferfromDyestoTiO 205 2 8.3.2 ApplicationofDyeSensitization 208 8.3.2.1 NonregenerativeDyeSensitization 208 8.3.2.2 RegenerativeDyeSensitization 211 8.4 PolymerSensitization 213 8.4.1 CarbonNitridePolymer 213 8.4.2 ConductingPolymers 214 8.5 Surface-Complex-MediatedSensitization 214 8.5.1 OrganicLigand 215 8.5.2 InorganicLigand 217 8.6 SolidSemiconductor/MetalSensitization 218 8.6.1 Small-Band-GapSemiconductor 219 8.6.1.1 BasicConcepts 219 8.6.1.2 CategoryinTermsofChargeTransferProcess 219 8.6.2 PlasmonicMetal 222 8.6.2.1 BasicConcepts 222 8.6.2.2 ProposedMechanisms 224 8.6.2.3 CriticalParameters 225 8.7 OtherStrategiestoMakeTitaniaVisibleLightActive 226 8.7.1 BandGapEngineering 226 8.7.1.1 MetalDoping 226 8.7.1.2 NonmetalDoping 227 8.7.1.3 Codoping 227 8.7.2 Structure/SurfaceEngineering 228 8.8 Conclusions 230 Acknowledgment 231 References 231 9 PhotoelectrocatalysisforWaterPurification 241 RossanoAmadelliandLucaSamiolo 9.1 Introduction 241 9.2 PhotoeffectsatSemiconductorInterfaces 242 9.3 WaterDepollutionatPhotoelectrodes 245 9.3.1 MorphologyandMicrostructure 245 9.3.2 EffectofAppliedPotential 247 9.3.3 EffectofpH 247