Preparation And Oxygen Evolution Of Multicomponent Transition Metal-based Electrocatalysts

With the growth of global energy demand,traditional fossil energy has been unable to meet the social demand,so the development of low-cost energy conversion equipment to reduce human dependence on fossil resources,has become an urgent research issue.As a low-carbon sustainable device,oxygen consuming batteries such as hydrogen oxygen battery,metal oxygen battery and methanol/ethanol oxygen battery are undoubtedly at the top of the green energy pyramid.Oxygen production by electrolysis of water is one of the common technologies.In the process of electrolysis of water,the use of catalyst can effectively reduce the anode overpotential and improve the reaction rate,so as to achieve efficient utilization of energy.However,in recent years,transition metals such as iron,copper,nickel,cobalt,manganese and other non-precious metal catalysts have been paid more attention because of their low price,large storage capacity,and high catalytic activity and stability of OER in basic electrolytes.However,some research results show that the traditional single non-precious metal catalyst has low catalytic activity or poor stability and other defects.Therefore,it is imperative to prepare efficient and stable multicomponent transition metal-based catalysts by a simple method.In this paper,composite catalyst Fe_xCu_yNi_1-x-y/FeOOH/NiOOH/CuO and amorphous carbonate catalyst CoCrFeMnMoCO₃ were synthesized by electrodeposition and hydrothermal methods,respectively.The composition and structure of the synthesized products were regulated and optimized to improve the catalytic ability of anodic OER reaction in the process of electrolytic water reaction.Specific research work is as follows:（1）Fe_xCu_yNi_1-x-y/FeOOH/NiOOH/CuO（FCN-x）transition metal composite catalyst was prepared by electrodeposition on glass carbon sheet.Forty-one kinds of Fe_xCu_yNi_1-x-y/FeOOH/NiOOH/CuO composites were reported by adjusting the ratio of Fe:Cu:Ni,and the mechanism of the influence of components on the OER properties of catalysts was investigated.Ni-Cu is an alloy material with high synergistic and electronic effects,and the addition of Fe can promote the rapid transfer of charge.The catalyst prepared by electrodeposition has loose porous structure and can provide abundant active sites,which can effectively improve the activity of the catalyst.The catalyst（FCN-7）showed the best catalytic activity when Fe:Cu:Ni=1:2:7 after extensive screening in 0.1 mol L^-1 KOH solution.At a mass specific activity of 2.21 A g^-1,it showed a relatively low overpotential（170.3 m V）,with a Tafel slope of 75.9m V dec^-1 and a loss of activity of about 29%after 10 hours of timing amperage testing.（2）Amorphous carbonates of Co,Cr,Fe,Mn and Mo were synthesized by hydrothermal method.The effect of hydrothermal time on the catalytic activity of amorphous carbonate CoCrFeMnMoCO₃ was studied.Its activity was tested in 1.0 mol L^-1 KOH solution,when the current density was 10 m A cm^-2,the amorphous compound of Co,Cr,Fe,Mn and Mo prepared at 80℃for 6 h had the best catalytic performance,and its overpotential was 301.5 m V.The Tafel slope is as low as 37.91 m V dec^-1;Chronopotentiometry was used to test the stability and durability of the catalyst.After 50 hours of ultra-long durability test,the overpotential was almost unchanged,which was better than most transition metal oxygen evolution catalysts reported in recent literature.