化学信息学

Carbonsupportedplatinum–goldalloycatalystfordirectformicacidfuelcells碳负载Pt-Au型催化剂的直接甲酸燃料电池钟永红、丁淑英一、数据库和期刊杂志主要英文数据库:Elsevier,Science,Nature等二、文章信息和关键字四、摘要三、作者香港科技大学机械工程学系五、引言•Liquidfuel-feedfuelcells,giventheirrelativelysimplesystemdesignandcelloperation,areattractiveasapowersourceforportableelectronicdevices.Amongvariousliquidfuel-feedfuelcells,directmethanolfuelcells(直接甲醇燃料电池)(DMFCs)havebeenextensivelyinvestigatedandasignificantprogresshasbeenmadeinthedevelopmentofthistypeoffuelcell.•液体燃料电池因为其设计和使用相对较简单，对于便携式电力装置，是一种比较有吸引力的能源。各种燃料电池中，甲醇燃料电池已经被广泛研究，并取得重大进展。•However,despitemanyyearsofintensiveresearchintotheDMFCtechnology,inherentlimitationsstillremain.Methanolistoxicandsluggishintheanodicoxidationkinetics;moreover,DMFCssufferfromfuelcrossoverthroughNafion-basedmembranes.Forthesereasons,increasingattentionhasbeenpaidtothesearchforalterativeliquidfuels.•由于集中研究甲醇燃料电池技术，比较局限。在阳极氧化动力学上反应迟钝，有毒，更重要的是，甲醇燃料电池的燃料要交叉通过全氟磺酸膜。越来越多的研究改变液体燃料。•FormicacidexhibitsasmallercrossoverfluxthroughNafionmembranethandoesmethanol,allowingtheuseofhighconcentratedfuelsolutionsandthinnermembranesindirectformicacidfuelcells(DFAFCs).DFAFCsalsohaveahigherelectromotiveforce,ascalculatedfromtheGibbsfreeenergy,thanDMFCs.Inaddition,formicacidisastrongelectrolytethatfacilitatesprotontransportincatalystlayers.•甲酸比甲醇表现出更低的交叉跨界，甲酸燃料电池可以利用更高浓度的液体燃料和更薄的薄膜，用Gibbs自由能计算，甲酸燃料电池比甲醇有更高的电动势，甲酸是强电解质，可以促进质子在催化剂层中的流动。相比甲醇燃料电池，甲酸电池可以变得更轻、更小、更低温。1、试剂六、实验20mlH2PtCl6和HAuCl4DMF溶液混合、紫外灯照射3小时182mg碳粉末、用力搅拌40ml0.2MNaoH溶液形成沉淀，离心分离出沉淀乙醇和水多次洗涤、烘干2、催化剂的制备Electrochemicalmeasurements（电化学测量）werecarriedoutbycyclicvoltamm-etry(CV)usingapotentiostat（稳压器）.Aconventional,three-electrodecell（三电极电解池）consistingofGCEwithanareaof0.125cm2astheworkingelectrode（电极）,Ptfoilasthecounterelectrode,andasaturatedcalomelelectrode（饱和甘汞电极）(SCE)asthereferenceelectrodewasused.Thereferenceelectrode（参考电极）wasplacedinaseparatechamber（在一个单独的室）,whichwaslocatedneartheworkingelectrodethroughaLuggincapillarytube（毛细管）.TheworkingelectrodewasmodifiedwiththecatalystlayerachievedbydroppingasuitableamountofcatalystinkontheGCE.3、组装装置Thecatalystinkwaspreparedbyultrasonicallydispersing（超声分散）10mgof30wt%ofPt/CandPtAu/Cin1.9mLofethanol,towhich0.1mLof5wt%Nafion（全氟磺酸）solutionwasadded,andthedispersionwasultrasonicated(超声)for30mintoobtainahomogeneoussolution.Aquantityof6µLofthedispersion(分散)waspipettedout(吸取)onthetopoftheGCEanddriedinairtoyieldametalloading（金属负载）of72µgcm−2.TheCVexperimentswereperformedin0.5MH2SO4solutioncontaining0.5MHCOOHatascanrate（扫描速率）of50mVs−1.SolutionswerepreparedfromanalyticalgradereagentsandDIwater（分析纯试剂和去离子水）.Allexperimentsweredoneatroomtemperatureinnitrogen（氮气）(99.9%)saturatedsolutions.Thein-house(内部)fabricatedDFAFCconsistedofamembraneelectrodeassembly（膜电极）(MEA),withanactiveareaof2.3cm×2.3cm,sandwichedbetweentwobipolarplates（夹在两个双极板）,whichwerefixedby（固定）twofixtureplates（两个夹具板）.TheMEAconsistedofaNafion（全氟磺酸）115membraneandtwoelectrodes.Forfabricationoftheanode（制造的阳极）,commercial-grade30wt%Teflon-treatedcarbonpaper（聚四氟乙烯处理碳纸）(E-TEK)wasemployedasthebackinglayer.Thegasdiffusionlayer（气体扩散层）(GDL)wasfabricatedon装配在onesideofthecarbonpapercomprisingVulcanXC-72carbonand30wt%Teflon聚四氟乙烯.Tofabricateanodecatalystlayers制造阳极催化剂层,theanodeinks阳极油墨werepreparedbymixingin-house-made30wt%PtAu/CandPt/Cwith10wt%Nafioninethanol.Thepreparedanodeinks(阳极油墨)wereuniformlybrushed(刷)ontheGDLina5.3cm2areatogiveanapproximatemetalloading(金属负载)of2.0mgcm−2ontheanode(阳极).Finally,0.5mgcm−2ofNafion(全氟磺酸)wasuniformly(均匀地)coatedon(涂布在)theanodecatalystlayersanddriedat80◦Cinoven.ThecommercialPtblack（铂黑）(4mgcm−2)catalystwasusedatthecathode.(阴极).TheMEA（膜电极）wasformedbysandwiching(夹层铺料)theNafion115membrane（膜电极）betweentheanodeandthecathode（阴极）andbyhotpressing(热压烧结)at135◦Cunderapressure(压力)of4MPafor3min.TheMEAs（膜电极）fabricated（制造）byusingthePtAu/CandPt/Ccatalystsattheanodeweretestedinasinglecellfixture(电池夹具)(withanactiveareaof5.29cm2)havingthree-passserpentineflowchannels(有三通式蛇形流动通道)withbothwidthsanddepths(同时与宽度和深度)of0.7mm.TheMEAswereinitiallyactivated(最初激活)at60◦Cfor24hbyfeeding2Mformicacidataflowrate(在流量)of2mLmin−1totheanodeanddryoxygengasataflowrate(在流量)of100sccmtothecathode.Aftertheactivationprocess(在激活过程,)theDFAFCperformancecurves(性能曲线)wererecordedbyfixingtheloadcurrent(固定负载电流),whichwascontrolledwithanelectricloadsystem(电动加载系统)(BT2000,ArbinInstrument,Inc.).七、表征结果与讨论1、PtAu/C纳米粒子的物理化学性能表征：根据透射电镜（TEM）可以发现，Pt–Au纳米粒子呈球形均匀的分散并且没有发生聚集。asevidencedbythelatticefringesacrossthefullextentofimage.Fig.2showsthedistributionofparticlediameterestimatedfromanensembleof150particlesinanarbitrarilychosenareaoftheHRTEMimages.TheevaluationofthecharacteristicdiameterofthePt–Auparticlesindicatesasizedistributionfrom2.4to5.8nmwithanaveragediameterof3.8nm.任意一个区域以150个Pt–Au粒子为一组的粒子直径分布图，粒子直径大小分布为2.4-5.8nm，平均直径3.8nm元素组成为50.6at%Pt、49.4at%Au,Pt:Au比例为1：1ThecompositionofPt–AuparticlesanalyzedbyEDSisshowninFig.3.Ithasanelementalcompositionof50.6at%Ptand49.4at%Au,whichisconsistentwiththePt:Auratiointheprecursor(withplatinumtogoldmoleratioof1:1).结果表明碳粉上形成了Pt–Au合金，PtAu/C催化剂的平均直径为3.0nm。1、