Preparation Of PtNi Bimetallic Nanoparticles Supported On Porous Graphene And Electrocatalytic Performance For Methanol Oxidation

The direct methanol fuel cells have been widely regarded as a broad prospect for development in portable devices,because of their high conversion efficiency and non-pollution or lower pollution.The noble metal platinum is extensively used as a common electrocatalyst owing to its prominent electrocatalytic properties during methanol oxidation reaction.However,there are several factors which lead to the impediment of Pt in large-scale commercialization,including the high price and the adsorpotion of intermediate generated during the MOR.Therefore,developing a high-performance electrocatalysts is especially important research area for methanol oxidation reaction.The introduction of non-noble metal nickel into platinum could form PtNi bimetallic catalyst,which not only reduces the preparation cost,but also exhibits better electrocatalytic activity due to the synergistic effect between Pt and Ni.A suitable catalyst supporting material could provide more abundant active sites,specific surface area and be beneficial to disperse PtNi bimetallic nanoparticles,thereby further improving the catalytic performance.Based on the above analysis,a nanocatalyst with PtNi bimetallic NPs supported by electrochemical reduction method using porous graphene and nitrogen-doped porous graphene as supporting material was prepared,and the nanocatalyst was used for the methanol oxidation reaction.The main content s are as follows:（1）Preparation of PtNi/ERPGO nanocatalyst towards methanol oxidation reactionIn this work,PtNi bimetallic nanoparticles（PtNi NPs）supported on the electrochemically reduced porous graphene oxide（ERPGO）was fabricated by one-step electrochemical reduction of the precursor hybrid of H₂PtCl₆,NiSO₄ and porous graphene oxide（PGO）.The obtained PtNi/ERPGO was interrogated using energy dispersive X-ray spectroscopy（EDS）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,etc.The results demonstrated the successful introduction of pore structure in graphene and PtNi NPs were uniformly dispersed on the porous graphene（PG）supporting material.Furthermore,the electrocatalytic activity of the PtNi/ERPGO used for MOR was evaluated by electrochemical method.The enhanced electrocatalytic activity might be mainly because of the synergistic effect between Pt and Ni,and the existence of unique pore structure on the surface of graphene sheets.（2）Preparation of PtNi/PNG nanocatalyst towards methanol oxidation reactionIn this work,nitrogen-doped porous graphene materials were achieved by hydrothermal method.Then PtNi NPs supported on the nitrogen-doped porous graphene（PGN）was fabricated by electrochemical reduction of the precursor hybrid of H₂PtCl₆,NiSO₄.The obtained PtNi/PNG was interrogated using EDS,XRD,XPS,etc.The results showed that the porous structure in the PNG was not destroyed by high temperature hydrothermal and the PtNi NPs were uniformly dispersed on the PNG.Furthermore,the electrocatalytic activity of the PtNi/PNG used for MOR was evaluated by electrochemical method.Compared with PtNi/PG,PNG not only can better disperse PtNi NPs,but also exposed more abundant active sites,which was beneficial to electron transport and reaction,thereby indirectly accelerating the adsorption and oxidation of methanol.Therefore,PtNi/PNG exhibited better catalytic activity and stability.