Electroactivity of Pt-Ru-polyaniline composite catalyst-electrodes prepared by electrochemical depos(4)

Fuel Cell

S.Kim,S.-J.Park/SolidStateIonics178(2008)1915–1921

1917

Fig.2.X-raydiffractionpatternsofPt–Ru/CBscatalystspreparedfordifferentplatingtimesof(a)6,(b)12,(c)24,and(d)36

min.

electronmicroscopewithaspatialresolutionof1nm.Beforetakingtheelectronmicrographs,thecatalystsampleswereultrasonicallydispersedinisopropylalcohol,andadropoftheresultantdispersionwasdepositedanddriedonastandardcopper-gridcoatedwithapolymerfilm.Theappliedvoltagewas100kVforthecatalysts.

AnXRDanalysiswascarriedoutonthecatalyststhatwerepreparedfromdifferentconditions,bymeansofaRigakuD/MAX-ШBX-RaydiffractometerusingaCuKαsourceoper-atingat45kVand100mA.1TheXRDpatternswereplottedatascanningrateof4°min withanangularresolutionof0.05°for2θscans.X-raydiffractogramswereobtainedfor2θvaluesvaryingbetween30°and85°.TheaveragecrystallinesizesoftheparticlesweredeterminedfromtheX-raydffractograms,usingtheScherrerEq.(1)[41].L¼

0:9k

B2hcoshmax

ð1Þ

whereλistheX-raywavelength(1.54056ÅfortheCuKαradiation),B2θisthewidthofthediffractionpeakathalf-height,andθmaxistheangleatthepeakmaximumposition.

Fig.3.X-raydiffractionpatternsofPt–Ru/polyanilinecatalystspreparedfordifferentplatingtimesof(a)6,(b)12,(c)24,and(d)36min.

Table1

MeansizeandloadingcontentsofPt–Ru/CBscatalystsPlatingtimeCrystallinesizeParticlesizePtRuAlloyedRu(min)(nm)a(nm)b(wt.%)c(wt.%)c(%)6–

8.12.11.021125.2±0.35.43.91.224243.4±0.23.66.12.13236

4.2±0.2

4.6

7.2

3.1

26

aMeasuredfromXRDresults.b

MeasuredfromTEMresults.c

MeasuredfromICP-AESresults.

TheloadingmassofthePt–RuwasdeterminedbyInductivelyCoupledPlasma-AtomicEmissionSpectroscopy(ICP-AES)usingaJobinYvonUltima-CSpectrometer.2.4.Electrochemicalmeasurements

Electrochemicalmeasurementswerecarriedoutinaconven-tionalthree-electrodeelectrochemicalcellat25°C.ApieceofPtwirewasusedasthecounterelectrode,andKCl-saturatedAg/AgClwasusedasthereferenceelectrode.Theglassycarbonelectrode,asaworkingelectrode,wascoveredwithcatalystpowder.Allofthesolutionswerepreparedwithultra-purewater.Asolutionof1MCH3OHand0.5MH2SO4wasstirredconstantlyandpurgedwithultra-pureargongas.Electroche-micalexperimentswereperformedusinganAutolabwithaPGSTAT30(EcoChemieB.V.;Netherlands).3.Resultsanddiscussion

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