Synthesis Of WC Based Anode Catalyst For Alcohol Fuel Cell And Research On Mircostructure-electrooxidation Activity Relationship

In this dissertation,WC based composites were obtained through three different methods in which tungsten precursor was AMT.The electrocatalytic property of Pt deposited WC based catalysts and the relationship between electrocatalytic activity and microstructure of supports were evaluated and discussed.The following three aspects have been covered.1.The spray-dried spheres within a W/Pt multi-separation can be used to prepare discrete nano-sized core-shell WC@C/Pt nanocatalysts through a typical carburization production mechanism at 800 oC.In contrast with previous studies of the WC/Pt synthesis,the reaction observed here proceeds through an indirect annealing mechanism at 600 oC wherein species diffuse,thereby resulting in core-shell structure and Pt nanoparticles successfully polydispersed in size/shape and randomly scattered across the in situ produced C nanospheres.Through direct carburization or at higher initial hydrochloroplatinic acid concentrations,however,complete reaction with core-shell spheres were not observed.Indirect carburization reduces the strain felt by the bonds featuring the larger WC particles and allows the motion of carbon around and WC and Pt nanoparticles were reserved.The synthesis of WC-C compsite with highly-dispersed was carried out through polymerization-hydrothermal reaction and reduction carbonization procedure,using formaldehyde and resorcin as monomers,NH3·H2O as catalyst for polymerization,SDBS as surfactant,solution of water and alcohol as solvent,AMT as tungsten precursor,ferric nitrate as Fe precursor.The series of WC-C-Pt catalysts in which the WC-C supports were prepared from different mass of Fe?NO₃?₃.The WC-C-?0.10?Pt composite has uniform size,fine dispersion and the biggest specific surface area?146.14 m2/g?when the mass of Fe?NO₃?₃ equal to 0.10 grams.We also studied the electrocatalytic property for methanol oxidation on WC@C/Pt and WC-C-Pt series electrodes by electrochemical methods.It turned out that indirect-carb WC@C/Pt and WC-C-?0.10?Pt catalysts exhibited better catalytic activity for electrochemical methanol oxidation reaction.Compared with indirect-carb WC@C/Pt sample,WC-C-?0.10?Pt have advantages for methanol oxidation performance,it can be mainly attributed to the special structure,particle size,pore distribution,specific surface area and combination of the various components2.The composite precursors with W/Fe multi-components for preparing nanocomposites was obtained through AMT and Fe?NO₃?₃ self-assembled process in an aqueous solution.The synthesis of WC-CNT-Fe compsite was carried out through calcining at 600°C in air and reduction carbonization at 900°C procedure.In the WC-CNT-Fe composite,WC nanoparticles are first setting doped on carbon nanotubes?CNT?by in-situ growth in presence catalysis of transition metals and the agglomerate phenomena can be effectively avoided during carbonizing process.Meanwhile,introduction of transition metals even can provide a medium to supported Pt by a temperature-control metal replacement reaction and acquired a series of Pt@CNT-WC catalysts,the relationship between microstructure and electrocatalytic activity for catalysts were investigated through modified the mass ratio of W/Fe.Noticeably,an unusual electrocatalytic activity,low onset potential,a large electrochemical surface area and better durability are achieved for the Pt@WC-CNT catalyst with a mass ratio of W and Fe as 4:0.25.