Construction Of Pt/Metal Nitride/doped Graphene Two Dimensional Multilaer Catalyst And The Study Of Its Electrocatalytic Performance For Ethanol

Recently,the environmental problems caused by the economic development have become increasingly serious.The green energy will provide the impetus for human development and create a better life for us.Low-temperature fuel cells,such as the direct-alcohol fuel cells?DAFCs?,are widely recognized as a new type use of energy because of their higher energy conversion efficiency,lower pollution emissions and protability.However,anode catalysts in direct alcohol fuel cells are expensive,unstable,and prone to poisoning,which seriously hampers its marketization process.Unlike the traditional studies with the change of Pt-based catalysts or the modification of carbon carries,in this thesis,two dimensional double layer complex of transition metal nitride?M-N?M=Ti,Nb,Ta??and N-doped graphene are used as the carrier of platinum.Due to the advantages,such as the high Pt utilization,the high stability and the catalytic activity,of metal nitride and N-doped graphene,the catalyst could achieve three effects,including the low Pt loading,long durability and high CO tolerance,in electrocatalytic oxidation process.The details are as follows:The composite structure of Pt/TiN@N-doped graphene was synthesized by high temperature solid phase method.The influence of the thickness of N-doped graphene layer on the catalytic performance of the catalyst was systematically investigated.The crystal phase and morphology of the samples were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?and transmission electron microscopy?TEM?.The catalytic oxidation performance of the catalyst under acid conditions was tested by electrochemical technique?cyclic voltammetry and AC impedance method?.The results showed that the catalyst had high electrocatalytic activity to ethylene glycol.This may be due to TiN@N-doped graphene composite carrier has selective catalytic enhancement effect of ethylene glycol.The multilayer two-dimensional composite carrier of Nb₄N₅/N-doped graphene was synthesized by high temperature solid state method,and room temperature reduction method was used to load the platinum.The thickness of graphene in the carrier was altered by controlling the amount of carbon source.XRD,SEM,TEM,X-ray photoelectron spectroscopy?XPS?and Raman spectroscopy were used to characterize the obtained catalysts.Finally,by comparing the catalytic performances on the oxidation of methanol,ethanol and ethylene glycol of the catalyst,it was found that the Pt/Nb₄N₅/N-doped graphene catalyst with higher graphene content showed better electrocatalytic activity.And its catalytic activity for the ethanol oxidation is twice higher than that of commercial Pt/C catalyst.In order to explore the electrocatalytic activity of transition metal nitrogen oxides,we mainly use the high temperature solid state method to synthesize Pt/TaON/N-doped graphene composite two-dimensional multilayer catalyst.Using butanol as solvent,the content of graphene carbon material was increased,and the effect of graphene layer thickness on the catalytic performance of the catalyst was studied.Based on the structure characterization,the surface chemical analysis and electrochemistry test of the catalyst,it was found that the catalyst with high degree of graphene showed excellent CO tolerance and showed higher activity than commercial Pt/C in the electro-catalytic oxidation of various alcohols.