RotatingElectrodeMethodsandOxygenReductionEl

ROTATINGELECTRODEMETHODSANDOXYGENREDUCTIONELECTROCATALYSTSEditedbyWEIXINGStateKeyLaboratoryofElectroanalyticalChemistryChangchunInstituteofAppliedChemistryChangchunPRChinaGEPINGYINSchoolofChemicalEngineeringandTechnologyHarbinInstituteofTechnologyHarbinChinaandJIUJUNZHANGEnergy,MiningandEnvironmentNationalResearchCouncilofCanadaVancouver,BCCanadaAMSTERDAM�BOSTON�HEIDELBERG�LONDON�NEWYORK�OXFORDPARIS�SANDIEGO�SANFRANCISCO�SINGAPORE�SYDNEY�TOKYOElsevierRadarweg29,POBox211,1000AEAmsterdam,TheNetherlandsTheBoulevard,LangfordLane,Kidlington,Oxford,OX51GB,UK225WymanStreet,Waltham,MA02451,USA
2014ElsevierB.V.Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmittedinanyformorbyanymeanselectronic,mechanical,photocopying,recordingorotherwisewithoutthepriorwrittenpermissionofthepublisherPermissionsmaybesoughtdirectlyfromElsevier’sScience&TechnologyRightsDepartmentinOxford,UK:phone[phone];fax[phone];email:[e-mail]tyourrequestonlinebyvisitingtheElsevierwebsiteat:978-0-444-63278-4ForinformationonallElsevierpublicationsvisitourwebsiteatstore.elsevier.comPrintedandboundinPoland141516171810987654321PREFACERotatingdiskelectrode(RDE)androtatingring-diskelectrode(RRDE)techniquesareonekindoftheimportantandcommonlyusedmethodsinelectrochemicalscienceandtechnology,par-ticularly,inthefundamentalunderstandingofelectrochemicalcatalyticreactionmechanismssuchaselectrocatalyticoxygenreductionreaction(ORR).ThekineticsandmechanismsofORRcatalyzedbybothnoblemetal-andnonnoblemetal-basedelectrocatalystsarethemostimportantaspectsinfuelcellandotherORR-relatedelectrochemicaltechnologies.UsingRDEandRRDEtoevaluatetheactivitiesofcatalystsandtheircatalyzedORRmechanismsisnecessaryandalsooneofthemostfeasibleapproachesinthedevelopmentofORRelectrocatalysts.IndevelopingORRelectrocatalysts,significantchallengesexistinachievinghighcatalystactivityandstability.Tofacilitatetheefforttoovercomethesechallenges,abookwithfocusonthecatalyzedORRanditsassociatedtestinganddiagnosisofORRcatalystsisparticularlyuseful.AlthoughallresearchersintheareaofORR-relatedelectrocatalystsuseRDE/RRDEasroutinetechniquestoevaluatetheircatalystsandexplorethecatalyzedORRmechanisms,basedonourobservation,however,afunda-mentalunderstandingofthesemethodsseemsnotbeingfullyachieved.SomeconfusioncanbefoundintheliteraturewhenRDE/RRDEmethodswereusedandthedataexplained.There-fore,adetailedandcomprehensivedescriptionaboutthesetechniquesfromfundamentalstoapplicationsisdefinitelyhelpfulandmaybenecessary.InChapter1ofthisbook,thenecessaryparametersforbothRDE/RRDEanalysisinORRstudy,suchasO2solubility,O2dif-fusioncoefficient,andtheviscosityoftheaqueouselectrolytesolutions,arediscussedindepthintermsoftheirdefinitions,theoreticalbackground,andexperimentalmeasurements.Theeffectsoftype/concentrationofelectrolyte,temperature,andpressureonvaluesoftheseparametersarealsodiscussed.Toprovidethereaderswithusefulinformation,thevaluesoftheseparametersarecollectedfromtheliterature,andsummarizedinseveraltables.Inaddition,thevaluesofboththeO2solubilityanddiffusioncoefficientinNafion
membranesorionomersarealsolistedinthetables.Hopefully,thischapterwouldbeabletoserveasadatasourceforthelaterchaptersofthisbook,andalsothereaderscouldfinditusefulintheirexperimentaldataanalysis.InChapter2,tofacilitateunderstandingandpreparingthebasicknowledgeforrotatingelectrodetheory,boththeelectronPREFACExitransferandreactanttransporttheoriesattheinterfaceofelec-trode/electrolytearepresented.Regardingthereactanttrans-port,threetransportationmodessuchasdiffusion,migration,andconvectionaredescribed.AfocusingdiscussionisgiventothereactantdiffusionneartheelectrodesurfaceusingbothFick’sfirstandsecondlaws.Inaddition,basedontheapproachintheliterature,thekineticsofreactanttransportnearandwithinporousmatrixelectrodelayeranditseffectontheelec-trontransferprocessisalsopresentedusingasimpleequivalentelectrode/electrolyteinterface.InChapter3,togivesomebasicknowledgeandconcepts,somefundamentalsaboutthecatalystactivityandstabilityofORRelectrocatalysts,whicharethetargetedresearchsystemsbyrotatingelectrodemethods,arepresented.Adetaileddescriptionabouttheelectrocatalystsandcatalystlayersandtheirapplica-tionsforORRintermsoftheirtypes,structures,properties,catalyticactivity/stability,aswellastheirresearchprogressinthepastseveraldecadesarealsogiven.Furthermore,boththesynthesisandcharacterizationmethodsforORRelectrocatalysts,andthefabricationproce