Preparation Of Heteroatom-doped Carbon-supported Platinum Nanocomposites And Their Electrocatalytic Performance

Direct methanol fuel cells have the characteristics of rapid start at low temperature,convenient environmental protection and simple battery structure.But its catalytic performance needs further improvement.Graphene,mesoporous carbon and carbon nanotubes have the advantages of large specific surface area and good electrical conductivity,which make them widely used in carbon carriers of direct methanol fuel cells.Using graphene,mesoporous carbon and carbon nanotubes as carriers,this paper mainly includes the following two parts:N,P-doped mesoporous carbons were prepared using soft template method and heat treatment.PtCo_x@NPMC nanocomposites were prepared using N,P-doped mesoporous carbon and chloroplatinic acid as precursors.Undoped Pt@MC,PtCox@MC catalysts and Pt@NMC nanocomposites with nitrogen doping but no cobalt were prepared using similar method.Their characterizations and electrochemistry performance tests were carried out.Electrochemicalperformancetestsshowedthatthecurrentdensityof PtCo_x@NPMCcatalyst in the methanol oxidation of acidic and alkaline solutions were reached 1459mA/mg Pt and 1250mA/mg Pt.The current density of PtCo_x@NPMC in chronamperometry test remained stable,indicating that it has excellent catalytic performance for methanol electrooxidation.At the same time,PtCo_x@NPMC catalysts have better catalytic performance and stability in the oxygen reduction test.Nitrogen and phosphorus doping can improve the dispersion of the catalyst nanoparticles,and the alloy formed of platinum and cobalt can also geatly improve the performance of the catalyst.N-doped carbon nanotubes were prepared by chemical vaporous deposition method and added to the preparation process of graphene/platinum catalyst to prepare Pt/G-C15.Pt/G-C20,Pt/G-C10 with different carbon nanotube contents and Pt/G without Carbon nanotubes were prepared using similar method.Electrochemical performance tests showed that Pt/G-C15 catalyst has the best catalytic activity,and its current density of CV reached1228.4 mA/mg Pt in 0.5 mol/L KOH+1mol/L CH₃OH solution,which was higher than thoes ofPt/G-C20,Pt/G-C10 and Pt/G.The current density of the Pt/G-C15 catalyst in the chronoamperometry test curve remained at a relatively high level then Pt/G-C20,Pt/G-C10 and Pt/G,Proving that it has good stability during the catalytic reaction of alkaline fuel cells.Pt/G-C15 catalysts have better catalytic performance and stability in the oxygen reduction test.The synergistic effect of carbon nanotubes and graphene in the composites improves the dispersion of platinum nanoparticles and optimizes the performance of graphene,thus improving the catalytic performance of graphene/platinum-based materials.