Preparation Of Transition Metal-based （Fe、Co、Ni） Compound Electrode Materials And Their Electrocatalytic Water Splitting Performance

Hydrogen energy has become one of the optimal solutions for meeting the challenge about energy and environmental crises due to its clean and environmentally friendly characteristics.Electrolysis of water,as a safe and sustainable technology,can fabricate hydrogen energy economically and efficiently.On account of high-cost and poor stability properties,noble metal-based catalysts suffer from limited application in spite of their high activity.Therefore,it is urgent to develop novel catalysts for applying in water electrolysis with low-cost and efficient performance.Transition metals and their compounds potentially become a candidate of high-efficiency water electrolysis catalysts own to their abundant reserves,low-cost and multifarious valence state.However,a single catalyst material still fails to achieve high activity in comparison of noble metal-based counterparts.Previous reports have shown that the electrocatalytic activity can be effectively improved by means of tailoring the surface structure and electronic structure of the catalyst,result in a catalyst with low overpotential,high current density and long-term stabilization.This paper is dedicated to preparing economical and efficient Ni/Co/Fe-based catalyst in application of water electrolysis hydrogen production via multiple strategies,including morphology design,phase recombination,interface engineering,ion doping,etc.Furthermore.The main contents and results of this research are as follows:（1）Nitrogen doped nickel sulfide/cobalt sulfide（N-Ni₃S₂/Co S₂）catalyst with a heterogeneous structure were prepared by a simple in-situ cathodic electrodeposition method,where Ni Co LDH nanosheets uniformly grown on the nickel foam（NF）.The obtained N-Ni₃S₂/Co S₂/NF catalyst exhibits excellent electrocatalytic activity in both HER and OER because of numbers of lattice defects and heterogeneous interfaces in catalysts,which is beneficial for chemisorption of H⁺and OH^-.The current density of10 m A·cm^-2driven by N-Ni₃S₂/Co S₂in 1.0M KOH of OER and HER requires only 245and 100 m V low overpotential.Besides,OER and HER have lower Tafel slopes of 84m V·Dec^-1and 89 m V·Dec^-1,respectively.As a dual-function catalyst,the N-Ni₃S₂/Co S₂catalyst can drive the current density of 10 m A·cm^-2in the hydrolysis system at an ultralow cell voltage of 1.56 V during the total hydrolysis of water,accompanying with excellent long-term stability.（2）Through a facile room temperature immersion etching method,Sulphur-doped Fe Ni layered double hydroxide（S-Ni Fe（OH）_x）with precise anion regulation have been prepared on Fe Foam（FF）.Because of the precise doping of sulfur ions,the catalyst has the excellent electronic structure,which is conducive to the adsorption of OH^-and the precipitation of O₂.The obtained S-Ni Fe（OH）_x-0.01/FF can drive the current density of100 m A·cm^-2in 1 M KOH electrolyte with a low overpotential of only 270 m V.Additionally,it also has a low Tafel slope(86 m V Dec^-1)and excellent long-term stability.This paper processes several advantages,such as facile method,low-cost raw material,mild experimental conditions and economical preparation.And the as-prepared catalyst material has good electrolysis water catalytic activity,which provide some reference value for the design of efficient and cheap electrolysis water catalyst.