ElectroactivityofPt-Ru-polyanilinecompositecatalyst-elecFuelCellAvailableonlineatSolidStateIonics178(2021)1915–1921/locate/ssiElectroactivityofPt–Ru/polyanilinecompositecatalyst-electrodespreparedbyelectrochemicaldepositionmethodsSeokKima,Soo-JinParkb,aAdvancedMaterialsDivision,KoreaResearchInstituteofChemicalTechnology,P.O.Box107,Yuseong,Daejeon305-600,SouthKoreabDepartmentofChemistry,InhaUniversity,253,Nam-gu,Incheon402-751,SouthKoreaReceived6September2021;receivedinrevisedform17December2021;accepted21December2021AbstractTheelectrochemicaldepositionofPt–Runanoparticlesonconductingpolymersupportsandcarbonsupports,aswellastheirelectro-catalyticactivities,wereinvestigated.Pt–Rucatalystsof3–8nmaveragesizeweregrownonsupportsbystep-potentialplatingmethods.Thecatalysts'loadingcontentswereenhancedbyincreasingtheplatingtimeofthedepositionmethod.Polyanilineandcarbonblacks(CBs)wereselectedandcomparedascatalystsupports.TheparticlesizesandmorphologicalstructuresofthePt–Ru/supportcatalystswereevaluatedusingX-raydiffraction(XRD)andtransmissionelectronmicroscopy(TEM).TheelectrochemicalbehaviorsofthePt–Ru/supportcatalystsformethanoloxidationwereinvestigatedaccordingtotheircharacteristiccurrent-voltagecurvesandchronoamperometryinamethanolsolution.Asaresult,theelectrochemicalactivitywasenhancedwithincreasedplatingtime,reachingthemaximumat24min,andthendecreased.Thespecificcurrentdensityforthepolyaniline-supportedcatalystswashigherthanthatfortheCBs-supportedones.Theenhancedcatalyticactivitywasrelatedtothehigherelectricalconductivityofthepolyaniline,theincreasedelectrochemicalsurfaceareaofcatalysts,orthehigheriondiffusionbehaviours.2021ElsevierB.V.Allrightsreserved.Keywords:Catalyst-electrodes;Platingmethods;Electroactivity;Supportmaterials;Fuelcells1.IntroductionDirectmethanolfuelcells(DMFCs)areanattractivepor-tablepowersourceowingtotheirhighenergydensity,easyfuelhandling,andalowoperatingtemperature[1–4].However,DMFCsentailsomeserioustechnicalobstacles.Oneistherelativelyslowkineticsofthemethanoloxidationreactionatananode,whichleadstohighover-potentials[5].Platinum(Pt)hasahighactivityformethanoloxidation,andhasbeenusedinanodeelectrocatalystsformanyyears[6–8].However,thePtelectrocatalystwillbepoisonedbyintermediatesofmethanoloxidation,suchasCO.Sincethemid-1970s,topromotemethanolelectro-oxidationbyPt,thecatalystsurfacehasbeenmodifiedbytheadditionofasecondmetaltoPt[9–11].TheresultingPt–Rubinarymetalliccatalystiscommonlyacceptedasthebestelectrocatalystformethanoloxidation[12–15].TheCorrespondingauthor.Tel./fax:+82328608438.E-mailaddress:sjpark@inha.ac.kr(S.-J.Park).0167-2738/$-seefrontmatter2021ElsevierB.V.Allrightsreserved.doi:10.1016/j.ssi.2021.12.074otherissueinDMFCsisthemethanolcrossoverfromanodetocathodeacrossthemembrane.Itiswellknownthatmethanolcrossoverlowersfuelutilizationandcausescathodeover-potential[16–19].Pt–Rucatalystscanbepreparedbyanelectrochemicalplatingmethodaswellasaconventionalchemical-reductionmethod[20–22].Recently,electrochemicaldepositionofmetalcatalystshasbeenreceivingmoreandmoreattentionduetoadvantagessuchasitshighpurityofdeposits,simpledepositionprocess,andeasycontroloftheloadingmass.Byapplyingaspecificcurrentforashorttime,andthenrepeatingtheprocessduringelectrodeposition,eachcycleofthisprocesscangeneratenewmetalparticles[23].Therefore,bycontrollingthem...