《文献汇报》PPT课件.ppt

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1、1PaperReview李俊乾化学工程（专）14102932Synthesis,characterizationandelectrochemicalstudiesofnano-structuredCaWO4asplatinumsupportforoxygenreductionreaction(纳米钨酸钙的合成、表征和其负载铂对氧还原反应的电催化)2Literaturesource3ContentsIntroduction12Experimentalsection1Conclusions234Resultsanddiscussion41.IntroductionInrecentyea

2、rs,protonexchangemembranefuelcells(PEMFCs)havebeenrecognizedaspromisingdevicesforportableandtransportapplicationsduetotheirgoodenergyconversionefficiency,highpowerdensity,lowoperatingtemperature,andeasytransport.PEMFC’Sworkingprinciple:51.IntroductionThecathodicreactionofoxygenreductionreactio

3、n(ORR)TheanodicreactionofhydrogenoxidationreactionforH2+2M→2MH2MH→2M+2H++2e-O2+H++M+e-→MHO2MHO2+H++e-→MO+H2OMO+H++e-→MOHMOH+H++e-→M+H2OElectrocatalyticreactionmechanism:6Inthefuelcellintheworkprocess,theplatinumcatalystactivesurfaceareawillbegraduallyreduced,resultingintheattenuationoffuelcell

4、performance.thepropertiesofPt/PtMalloyrecessionschematicdiagram7Experimentalsection282.ExperimentalsectionSynthesisofnanostructuredCaWO4:80°CpH=7whiteprecipitateswerecollectedbycentrifugationNa2WO42H2O(5mM)CaCl26H2O(5mM)CaWO4mixedtogetherdriedinitiallyatroomtemperaturecalcinate500Cfor5h92.Expe

5、rimentalsectionCatalystpreparation:calciumtungstate(1)Graphite(2)CaWO4/graphiteelectrodeK2PtCl4（2.5mM）H2SO4（0.25M）thecatalystofPt/CaWO4-graphite30wt.%ofn-eicosaneheatedelectrochemicallyprecipitated1023Resultsanddiscussion113.ResultsanddiscussionTheapproximatecrystallitesizesofsampleswereestima

6、tedbytheScherrer’sformula:TheparticlesizeandmorphologyofCaWO4wereexaminedusingTEM，D=10–25nm.123.ResultsanddiscussionThesereductionpeaksarenotsymmetricbecauseofdepletionofPtCl42-ionsinthevicinityoftheelectrodesinpotentialsmorenegativethanthepeakpotentials.Cyclicvoltammogramsduringelectrodeposit

7、ionPtonbothgraphiteandnano-CaWO4/graphite.133.Resultsanddiscussion(a)and(b)ScanningelectronmicroscopyimagesofPt/CaWO4-graphite.Inthesepictures,brighterareascorrespondedtoPtandCaWO4thattheplatinumparticlesaredispersedoverthesurfaceofthes