Preparation And Properties Of Transition Metal Based Electrochemical Catalysts

As fossil fuels decline and environmental pollution aggravate,future societies have to rely on sustainable and regenerative energy sources for development.Hydrogen（H₂）gas produced by electrochemical water splitting,which can be powered by electricity from renewable sources,is deemed as a potential substitute because of its high energy density and environmental benignity.However,the practical applications of hydrogen production by electrochemical water splitting（EWS）has been greatly hindered because the splitting reactions,including the anodic oxygen evolution reaction（OER）and the cathodic hydrogen evolution（HER）are strongly uphill with large overpotentials.Therefore,the development of highly efficient and low-cost electrocatalysts such as earth abundant-based electrode materials is of great significance.In this paper,three kinds of transition metal-based electrocatalysts are prepared using flexible conductive carbon cloth（CC）as the substrate for EWS.1.Taking ZIF-67nanosheets as template,Mo source is introduced by solvothermal method and the composition and morphology of the material are changed simultaneously.Then,Mo-Co P_n-m material is obtained by phosphating treatment.By adjusting the doping amount of Mo and phosphating time,the electronic structure of cobalt phosphide can be modulated.Afterwards,the electrocatalyst Mo-Co P₁-10 with food performance is obtained.2.Using cobalt nitrate,nickel nitrate and ammonium metavanadate as Co,Ni and V metal sources respectively,the composite of Co/Ni vanadate and phosphide is synthesized by hydrothermal treatment and phosphating treatment.Through tuning propotions of Co and Ni,the morphology and electronic structure of the CNVO/CNP-3 material are optimized.3.Ni P/Fe P nanocubes with amorphous phase and Co P nanosheet with crystalline phase composite grown on carbon cloth（NiP/FeP/CoP）are constructed via the oxidation and phosphating process.The improved electrocatalytic activity of NiP/FeP/CoP is ascribed to the construction of composite material which optimizes the electronic structure of the catalyst and existence of amorphous structure which increases the number of exposed active sites.The materials are characterized by SEM and TEM,XRD and XPS are used to analyze the structure and surface composition.Electrochemical methods such as CV,LSV,I-t and muti-current step test are used to value the electrocatalytic properties of various materials.