Construction Of Nickel-based Transition Metal Electrocatalysts And Study On Catalytic Property

Hydrogen energy is regarded as the most promising energy source in the 21st century because of the advantages of cleanliness,high energy density and carbon-free.The conversion and utilization of electric energy efficiently can be achieved by the combination of photovoltaic,wind power and electrocatalytic hydrogen production with a wide range of raw materials and pollution-free production process.It is necessary to develop efficient catalysts or replace oxygen evolution reaction（OER）with organic small molecule oxidation to reduce the reaction barrier and energy consumption because of the slow kinetics of anodic OER in the process of water electrolysis hydrogen production and emormous barrier of reaction energy.Nickel-based transition metal compounds have glorious electrical conductivity,unique electronic structure and excellent catalytic activity.In recent years,an important research direction in the field of electrocatalysis is to exploit high-efficiency electrocatalyst with abundant nickel ore reserves based on the abundent reserves of nickel ore.In this paper,the nickel-based transition metal electrocatalysts with high electrocatalytic performance was designed and synthesized by using interface engineering and atom doping strategy.Then the controlled synthesis and characterization,electrocatalytic performance and the effect of heterogeneous interface and atom doping on electron transfer were investigated.The specific research content are as follows:（1）Construction of Fe-Ni₃S₄@Ni（OH）₂ coated nanosheet electrocatalyst and study on electrolysis performance in alkaline solution.In this study,Fe-Ni₃S₄nanosheets supported on the nickel foam were prepared by two-step hydrothermal method under the guidance of atomic doping strategy,and then Ni（OH）₂ was deposited on the surface of Fe-Ni₃S₄ by electrochemical deposition to form the coating structure Fe-Ni₃S₄@Ni（OH）₂.The overpotentials of Fe-Ni₃S₄@Ni（OH）₂ are 48 m V of the cathodic hydrogen evolution（HER）and 248 m V of OER at the current density is 10 m A cm^-2,respectively.Fe-Ni₃S₄@Ni（OH）₂ was used as the cathode and anode to construct a dual-electrode cell.The applied voltage was 1.602(η₅₀)and 1.823V(η₈₀),respectively.Fe-doping can adjust the electron configuration in the material and stimulate the electron interaction between different components,thus improving the electrochemical performance.（1）Rational designing Schottky heterojunction to regulate local charge distribution for efficient urea oxidation and hydrogen evolution reaction.Guided by density functional theory（DFT）calculations,we propose a simple strategy to synthesize MoS₂/Ni₃S₂ electrocatalyst,which was used as a bifunctional electrocatalyst for overall urea electrolysis.It only gives low overpotentials of 109 m V to deliver 10 m A cm^-2 for anodic urea oxidation reaction（UOR）and 166 m V to deliver 10 m A cm^-2 for HER in 1.0M KOH,respectively.Being adopted as both cathode and anode to assemble a two-electrode cell,the MoS₂/Ni₃S₂ also revealed excellent performance for urea oxidation.The band bending on Mott-Schottky heterogeneous interface promotes charge redistribution,generates strong built-in electric field,improves catalytic activity and makes the interface relatively stable.Furthermore,urea molecules contain both electron-donating groups（amino）and electron-absorbing groups（carbon）,the strong built-in electric field generated by Mott-Schottky heterojunction will affect the adsorption behavior and catalytic activity of urea molecules on the catalyst surface.This study provides a feasible strategy and guidance for the development and application of nickel-based transition metal electrocatalysts,which has great potential in alleviating energy crisis and controlling environmental pollution,and great significance for the realization of the carbon peaking and carbon neutrality goals.