PtP Nanocrystals Supported On Transition Bimetallic Phosphides/carbon Composites For Enhanced Methanol Oxidation Performence

In recent years,with the increasing global energy demands and the urgent issues of environment,people urgently need to exploit clean,cheap and renewable new energy sources to replace traditional fossil fuels.Among numerous new energy that has been developed,DMFCs has attracted more attention from researchers due to their abundant fuel sources,environmental friendliness,high energy density,as well as convenient storage and carrying.However,the commercial application of DMFCs is limited due to the low catalytic activity and inferior stability of anode catalysts.Therefore,it is still a hot research topic in the field of DMFCs how to regulate the catalyst components,morphology and build appropriate catalyst support to improve the platinum catalytic methanol electrooxidation performance.In this paper,the following research work was carried out based on the basis of the current development status of anode catalyst.Firstly,worm-like Pt P nanocatalysts supported on Ni Co2Px/carbon(Ni Co2Px/C)composites were prepared by a combined hydrothermal,low temperature phosphidation and Na BH4 reduction process.TEM and EDS indicates that the generation of worm-like Pt P nanocrystals was caused by the introduction of transition metal phosphatides,and the presence and content of phosphorus(P)play a critical role in constructing worm-like Pt P nanostructures.Electrochemical tests show that the resulting Pt P-Ni Co2Px/C catalyst exhibits an extremely high mass activity of 1361 m A mg-1Pt for methanol oxidation,which is 3.5-and 7.6-fold greater than those of commercial Pt/C(393 m A mg-1Pt)and homemade Pt/C catalyst(180 m A mg-1Pt),respectively,with the molar ratio of n(Ni(NO3)2·6H2O)and n(Co(NO3)2·6H2O)is 1:2 after hydrothermal reaction for 12 h at 120?.Meanwhile,the co-catalytic performence of Ni Co2 Px is better than those of the Co P and Ni2 P for Pt-catalyzed methanol oxidation due to the synergistic effect of Co and Ni.Secondly,based on previous research work,it is found that transitional bimetallic phosphide has better co-catalytic performance than single metal phosphide for Pt catalyzed methanol oxidation.We continue to study the co-catalytic effect of bimetallic phosphide(Fe Co Px)for platinum-catalyzed methanol oxidation.The hydrothermal time and the molar ratio of Fe Cl3·6H2O and Co Cl2·6H2O were optimized for construction of Fe Co Px/C composites.The Electrochemical test results indicated that when the molar ratio of Fe to Co salt was 1:1 and the hydrothermal reaction for 12 h at 120?,the Pt P-Fe Co Px/C catalyst has excellent catalytic performance for methanol oxidation.The research results show that the introduction of Fe Co Px can promote the electrocatalytic oxidation of methanol and effective adjust the composition of the catalyst.Moreover,TEM and EDS studies revealed that the introduction of Fe element has a certain inhibitory effect for the formation of worm-like Pt P catalyst.In this paper,while the introduction of co-catalyst including Ni Co2 Px or Fe Co Px,the composition and structure of the catalyst was effectively adjusted.Benefitting from the co-catalytic promotion of transition bimetallic metal phosphides(Ni Co2 Px and Fe Co Px)and the effective adjustment of structure and components for the catalyst,the Pt P-Ni Co2Px/C and Pt P-Fe Co Px/C catalysts have excellent catalytic performance for methanol electrooxidation.Furthermore,this study provides a novel design idea for the construction of 1D Pt-based alloy nanocatalysts.It provides a reference for the subsequent research and development of anode catalyst for DMFCs.