Construction Of Pt-Based Catalyst Modified By Bimetallic Phosphide/Phosphorus Doped Bimetallic Oxide Composites And Its Performance Of Methanol Electrooxidation

With the progress of present age and the development of science and technology,the storage of traditional energy has been unable to meet the growing needs of human development.Moreover,the use of traditional energy caused serious environment problems（such as acid rain,dust and greenhouse effect.）and aroused people’s wide attention.Therefore,the development of high energy density,low carbon and environmental protection of clean energy has become a hot research topic.Direct methanol fuel cell（DMFCS）,as a convenient mobile power supply device,is a hotspot in the field of energy research due to its high energy density,environmental friendliness and high conversion rate.The researches show that the Pt-based catalyst is one of the most commonly used anode catalysts for DMFCS,but there are still some problems,such as high cost,CO poisoning,poor catalytic performance.Therefore,the exploitation of catalysts with low cost,high performance and strong CO tolerance has become an effective approach for the commercial application of DMFCs.Some studies shown that the introduction of transition metal phosphates or oxides can effectively enhance the oxidation performance of methanol.In order to better settle the problems in methanol oxidation process,based on the study of transition metal oxide/phosphide used in MOR anode catalyst,this paper focuses on the construction of Pt-based catalyst composite support containing phosphorus and its effect on methanol oxidation performance.Specific research contents are as follows:（1）Nitrogen-doped porous carbon was formed by high temperature annealing with melamine and glucose as carbon source and（NH₄）₂HPO₄ as phosphorus source.Pt nanoparticles were supported by Na BH₄ reduction method,the nitrogen-doped porous carbon transition bimetallic phosphide composite catalyst of Pt-Ni WPx@NDPC was successfully constructed.Adjusted the annealing temperature and metal ratio to select the best annealing temperature and metal molar ratio.Electrochemical tests show that the catalyst Pt-Ni WP_x@NDPC-800 has the best electrocatalytic performance for methanol when the annealing temperature is 800℃and the Ni:W=1:1.Compared with the catalyst without（NH₄）₂HPO₄,the introduction of phosphorus increased the methanol oxidation activity effectively.（2）The results showed that the introduction of phosphorus enhanced the methanol oxidation activity.However,the composite carrier has some problems such as poor stability.Studies have shown that transition metal oxides have good stability,and transition metal oxides have more oxygen-containing groups.The synergistic effect between platinum and oxygen-philic components can enhance the oxidation of COads at adjacent Pt sites and enhance the activity of methanol oxidation.Pt-C/P-Cu WO₄composite support catalyst was successfully synthesized by hydrothermal,low temperature phosphating and Na BH₄ supported Pt nanoparticles using carbon black as support.The XPS test and electrochemical test showed that the doping of phosphorus enhanced the activity and stability of methanol oxidation compared with the unphosphorized Pt/C-Cu WO₄.The electrochemical specific surface area of Pt-C/P-Cu WO₄ was 103 m² g_Pt^-1 and the mass activity of Pt-C/P-Cu WO₄ was 1422 m A mg_Pt^-1under acidic electrolyte test conditions.The stripping voltammetry test of CO showed that Pt-C/P-Cu WO₄ had stronger resistance to CO poisoning.Pt-C/P-Cu WO₄is expected to be an ideal catalyst for methanol oxidation.