Design, Synthesis And Performance Study Of High Performance Anode Catalyst For Direct Methanol Fuel Cell

Direct Methanol Fuel Cell(DMFC)is considered as a power conversion device,electric vehicles,and other applications,which has the characteristics of high energy conversion efficiency and simple operation.it has received more and more attention.Platinum(Pt)are widely used as anode catalysts by DMFC.However,the price of Pt is expensive and the resources of Pt are scarce in the earth.Meanwhile,Pt suffer from carbon monoxide(CO)poisoning and deactivation,which limits the commercialization of DMFC.Therefore,it is very important to design new anodic catalysts to improve the conversion efficiency of DMFC.The catalytic activity of methanol oxidation was improved by the synthesis of Pt-based catalysts with low Pt loading or non-Pt catalysts.Pd is the congeners of Pt,they have similar crystal structures and electronic configurations so that they have similar chemical properties.The content of Pd in nature is more abundant than that of Pt.,Pd has higher oxidation activity than Pt for the intermediate products of methanol oxidation in alkaline environment.Therefore,Pd based catalysts have great research value.In order to accelerate the development of DMFC,this paper further improved the electronic structure and geometric structure of the catalysts:(1)Pt-skined platinum-silver bimetallic nanotubes(Pt/Pt Ag NTs)were synthesized step by step using template and replacement methods.Compared with Pt Ag bimetallic nanoparticles and commercialized Pt/C,it has better catalytic activity and stability in methanol electrooxidation.The formation of Pt thin layer on the surface of Pt/Pt Ag NTs is mainly due to the adjustment of the ratio of Pt to Ag precursors and nitric acid etching.The results have shown that the Pt skin on the Pt Ag bimetallic nanotubes significantly optimizes the electronic structure of Pt,greatly enhances the dissociative adsorption capacity of methanol.And the skin improved the CO poisoning resistance,current density of methanol oxidation,stability and accelerated electrode kinetics.In addition,this paper used the above-mentioned sacrificial template method to dope the third element rhodium(Rh)and palladium(Pd)to synthesize trimetal porous nanotubes Pt Ag Rh nanotubes(Pt Ag Rh NTs)and Pt Ag Pd nanotubes(Pt Ag Pd NTs),both of which showed excellent methanol oxidation performance and CO poisoning resistance.The peak current densities of methanol oxidation of Pt Ag Rh NTs /C and Pt Ag Pd NTs /C in acidic solution are 2.1 and 1.4 times of those of Pt Ag nanotubes(Pt Ag NTs/C),5.9 and 3.9 times of those of commercial Pt/C,respectively.This advanced one-dimensional construction also endows Pt Ag Rh NTs and Pt Ag Pd NTs with more favorable stability than Pd/C.This strategy can be used to synthesize high-performance catalysts for other alloys,providing more directions for a wide range of catalytic applications.(2)The palladium silver nanoflowers(PdAgNFs/C)with rich atomic defects and 3D hierarchical layers were successfully prepared by using carbon monoxide(CO)as structural guide and ascorbic acid as reducing agent in this paper.The chemical structure and surface structure of Pd-based alloy catalyst were adjusted.The methanol oxidation peak current density of PdAg NS/C catalyst is 1.6 times and 4.1 times higher than that of Pd NS/C and commercial Pd/C catalyst,and it has good electrooxidation stability.The modification of electronic structure,novel structure and abundant lattice defects of Pd are the important reasons for enhancing methanol oxidation.