CO monolayer oxidation at Pt nanoparticles supported on glassy carbon electrodes.pdf

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1、JournalofElectroanalyticalChemistry554
/555(2003)241
/251www.elsevier.com/locate/jelechemCOmonolayeroxidationatPtnanoparticlessupportedonglassycarbonelectrodesa,baaa,b,O.V.Cherstiouk,P.A.Simonov,V.I.Zaikovskii,E.R.Savinova*aBoreskovInstituteofCatalysis,Pr.AkademikaLavrentieva5,630090Novos

2、ibirsk,RussiabTechnischeUniversita¨tMu¨nchen,Physik-DepartmentE19,James-Franck-Str.1,D-85748GarchingbeiMunchen,GermanyReceived8November2002;receivedinrevisedform18February2003;accepted21February2003AbstractCOmonolayeroxidationonglassycarbonsupported1
/2nmPtnanoparticlesisstudiedusingpoten

3、tialsweepandpotentialstepmethods.TheCOstrippingpeakonthenanoparticlesissignificantlyshiftedtopositivepotentialsvs.thecorrespondingfeatureatbulkpolycrystallinePt.Currenttransientsatnanoparticulateelectrodesarehighlyasymmetricwithasteeprise,maximumatuCO:/1/20.8
/0.9,andaslowdecayfollowingt

4、.TheexperimentalresultsarecomparedtothetheoreticalmodelsofadsorbedCOoxidationdescribedintheliterature.Atentativemodelissuggestedtoaccountfortheexperimentalobservations,whichcomprisesspatiallyconfinedformationofoxygencontainingspeciesatactivesites,andslowdiffusionofCOmoleculestotheactivesi

5、tes,wheretheyareoxidized.TheupperlimitoftheCOsurfacediffusioncoefficientatPtnanoparticlesisestimatedasapproximately15214/10cms.#2003ElsevierScienceB.V.Allrightsreserved.Keywords:Oxidation;Carbonmonoxide;Chronoamperometry;Nanoparticles;Platinum;Glassycarbon1.Introductioncatalysisandelec

6、trochemistry,whichisalsorelevanttothedevelopmentofCOtolerantanodesfordirectCatalyticandelectrocatalyticpropertiesofnanopar-methanolandPEMfuelcells.WestudyCOmonolayerticleshavebeenthesubjectofnumerousinvestigationsoxidationunderpotentiodynamic(COstripping)aswell(seee.g.Ref.[1]andreferences

7、therein).Theincentivesaspotentiostaticconditions(chronoamperometry).havebeentwofold:first,togainfundamentalknowledgeSincetherateofCOmonolayeroxidationisaffectedconcerningthepropertiesofsmallconfinedsystemsand,bothbypotentialandtime,investigationofthereactionsecond,t