Functional Modification And Performance Study Of PT/CEO2 NWS Catalytic System For Direct Methanol Fuel Cells

The energy crisis became a more and more crucial problem for people,and also affected our daily life.Improving the utilization rate of energy was one way to mitigate the problem.Fuel cells,a device that converted chemical energy into electrical energy,which was expected to realize the maximization of energy conversion.Direct methanol fuel cell(DMFC),one of the types of fuel cell,got people's attention because of its merit,such as high energy density,high conversion rate and so on.Meanwhile the route to realizing its commercialization was still a long way,among whicht limited its commercialization was the catalyst.We mainly focused on the anode catalyst of DMFC,especially the support.The transition metal oxides ceria(CeO2)was selected as the object owing to its nature properties.Ceria nanowires,which was regarded as CeO2 NWS,was synthesized through a mild hydrothermal.In order to solve the poor conductivity of CeO2,urea was used as the source of nitrogen doped carbon layer,and CeO2 was modified by in-situ carbonization to improve electrical conductivity,at the same time the influence of the doping amount of urea was also studied and received the optimal proportion.Catalysts with different support,CeO2 NWS,CeO2 NP(homemade mesoporous)and XC-72(commercial),were compared to illustrate both catalytic activity and stability of the catalysts and Pt/CeO2 NWS showed the best catalytic activity.When the content of urea is 15%(rate of urea and the whole mass),Pt/CeO2Nws@C-N15 got the best performance and showed 1.79 times and 1.35 times than Pt/CeO2 NWS in electrochemical activity area(EAS)and the forward peak current density,respectively.The reason may be ascribed to the nitrogen doped carbon layer interacting with Pt and CeO2.As the increase of urea,interaction between Pt and CeO2 will weaken,which increased the conductivity and suppressed the migration and agglomeration of Pt nanoparticles.When the content of urea increased,the interaction between Pt and CeO2 would weaken.The specific wire-sheet inserted composite was prepared through combining graphite oxide(GO)with NWS for the first time.It can be found that Pt/GO4-CeO2 NWS showed best catalytic activity,namely the EAS and the forward peak current density of Pt/GO4-CeO2 NWS exhibited 2.57 times and 1.72 times than Pt/CeO2 NWS,respectively.The reason may be that the introducing of CeO2 NWS effectively reduced the stack of the GO and make Pt active sites more exposed,improving the utilization rate of Pt.Also the addition of CeO2 NWS formed a three-phase contact point:GO,CeO2 NWS and Pt and enhanced the stability of the catalyst at a certain extent.