Preparation Of Ni Fe-based Electrocatalyst And Its Performance In Water Electrolysis

The rapid development of the economy has led to a gradual increase in energy consumption.Compared to fossil fuels such as coal and oil,hydrogen and oxygen have advantages such as pollution-free,renewable,and zero carbon dioxide emissions.Therefore,to vigorously develop hydrogen energy and promote the energy revolution is the only way for world development.Electrolytic water process can not only produce high-purity hydrogen and oxygen by utilizing the abundant water resources on the surface,but also has the advantages of simple technology,convenient operation,green environmental protection,etc.It is considered as an ideal process for obtaining green energy.Suitable electrocatalysts can not only reduce the additional energy consumption in the electrolytic water process,but also improve its actual production efficiency.Therefore,they are of great significance for the large-scale application of electrolytic water technology.In recent years,the transition metal based electrocatalysts with rich reserves have gradually attracted people’s attention compared with the noble metal based electrocatalysts with high price and low stability.At present,there are still bottlenecks in the research of transition metal based electrocatalysis,and its catalytic activity and catalytic stability need to be further improved.In order to solve these problems,this thesis takes the cheap nickel iron based hydroxyl oxides and hydroxides as the research object,with the ultimate goal of improving the catalytic performance of the electrocatalysts,designs and synthesized a series of low-cost and high-performance electrocatalysts by doping and constructing heterostructures.The main research contents are as follows:（1）Nickel atom-doped ferric hydroxide(Ni_0.04-Fe OOH/CC)electrocatalyst was successfully prepared on carbon cloth substrate by simple hydrothermal method.Its catalytic performance is far superior to that of pure ferric hydroxide（Fe OOH/CC）.Further research has shown that the main reason for the improvement of catalyst activity is the doping effect of nickel atoms.The electrocatalyst doped with nickel atoms has a better crystallinity,a larger specific surface area,an increase in the electrochemical active area involved in the reaction,and a decrease in the resistance value.These changes are conducive to improving the electrocatalytic activity of the material.（2）In order to further improve the electrolytic water performance of the catalyst,based on the principle that the synergistic effect of binary metals can control the electronic structure of the catalyst,on the basis of（1）research,the binary basic nickel iron carbonate(Ni_0.75Fe_0.19CH/CC)with higher catalytic activity was successfully prepared by increasing the input of nickel source.The electrochemical test shows that the binary Ni_0.75Fe_0.19CH/CC has higher water electrolysis performance than the monovalent Ni CH/CC and the Ni_0.04-Fe OOH/CC synthesized in（1）.At the current density of 10 m A cm^-2,the over-potential of oxygen evolution of the electrocatalyst is 250 m V.（3）The heterostructure modification strategy was used to optimize the modification of the electrocatalyst to achieve the purpose of industrial application.On the basis of（2）research,Ni Fe/Ni Fe CH/CC composite electrode material with heterostructure was successfully prepared by electrodeposition of Ni Fe alloy at constant pressure.The results show that Ni Fe/Ni Fe CH/CC electrocatalyst has better water electrolysis performance.At 10 m A cm^-2 current density,the overvoltage of oxygen evolution reaction is 230 m V,the overvoltage of hydrogen evolution reaction is 92 m V,and the decomposition voltage required for overall water splitting is only1.49 V,and the catalytic performance is far better than that of commercial electrolytic cells.In addition,the composite has the characteristics of self-optimizing performance.After 150 h of electrochemical test,its oxygen evolution performance is improved by 21%compared with the original.