Preparation Of Transition Metal Dihalides And Investigation Of Their Hydrogen Evolution Properties For Splitting Water

Hydrogen is highly efficient,renewable and environmentally friendly,and is considered as an important energy carrier to solve the global environment and energy crisis.Compared with traditional hydrogen production technology,electrochemical hydrogen production technology process exhibits the advantages of being simple and stable and environmentally benign,which has attracted great research interest.Currently,noble metal Platinum based catalysts are still the most effective electrocatalysts for water splitting hydrogen production,but their scarcity and expensive price limit their industrial applications.Therefore,finding highly active and low-cost catalysts is of great significance for large-scale application in hydrogen production.Transition metal dihalides（TMDs）are a class of layered materials that have been extensively studied due to some of their unique mechanical,electronic,catalytic,and electrochemical properties.Among them,single or few layers transition metal dihalides can exhibit different properties than their bulk counterparts including:a large specific surface area,which is able to expose more active sites,and large quantum size effects（light,electricity and superconductivity）.This paper mainly explores the preparation methods of TMDs（mainly aimed at the optimization and modification of MoS₂）and their electrocatalytic hydrogen evolution performance.Firstly,MoS₂/MXene nanosheets with sulfur vacancies（denoted as MoS₂/MXene-SV）were prepared by a hydrothermal method using MXene as conductive substrate and sodium molybdate dihydrate and thiourea as raw materials,followed by annealing treatment under hydrogen environment.It exhibited an overpotential of only 140 m V,a low Tafel slope of 66 m V dec^-1,an electrochemically active area of 43.5 m F cm^-2 at a current density of 10 m A cm^-2,highly efficient hydrogen evolution in acidic media,and good stability maintained over 24 h by chronoamperometric tests at this current density.Secondly,the transition metals（Ni,Fe,Co,Mn,etc.）are doped into TMD materials such as MoS₂ by electrochemical exfoliation.The prepared transition metal Ni doped MoS₂ nanosheet catalyst can achieve excellent HER performance and good stability in alkaline medium.At a current density of 10 m A cm^-2,the overpotential exhibited was only 145 m V,the Tafel slope was as low as 89 m V dec^-1,and the electrochemically active area reached 3.8 m F cm^-2,enabling hydrogen evolution under alkaline environment better than most MoS₂ based electrocatalysts.