Molybdenum Disulfide-based Catalyst For Hydrogen Evolution Reaction

Hydrogen（H₂）is considered the best clean energy carrier.Hydrogen production from water electrolysis is one of the most promising hydrogen production methods.The key to the development of water electrolysis hydrogen production technology lies in the electrocatalytic hydrogen evolution reaction（HER）catalyst.To date,the most widely used HER catalysts in industry are noble metals（Pt）with low overpotential and high efficiency,but their reserves are low and their cost is high.Therefore,there is an urgent need to develop high-performance,low-cost alternatives.Molybdenum disulfide（MoS₂）has been theoretically calculated to be an excellent substitute for platinum-based catalysts.The research shows that the catalytic active sites of MoS₂ are mainly at the edge of the material,the substrate surface is inert,and 1T-MoS₂ has higher catalytic performance than 2H-MoS₂ in the two phases of MoS₂.Tuning the MoS₂ pore structure,increasing the specific surface area and transforming the phase can effectively improve the HER performance.The main research contents of this paper are as follows:（1）MoS₂/CQDs doped with carbon quantum dots（CQDs）was synthesized by a hydrothermal method.Compared with pure MoS₂,the three-dimensional size of MoS₂/CQDs is reduced by nearly ten times,and the diameter of the curd is reduced from～600 nm to～80 nm.MoS₂/CQDs are uniform nanometers.Flower-like,the increase in specific surface area promotes the improvement of HER performance.The Zn₂Co-MoS₂/CQDs composite catalyst was further doped with transition metals,and the phase transition from 2H-MoS₂ to 1T-MoS₂ was realized.After electrochemical tests,Zn₂Co-MoS₂/CQDs overpotential at a current density of 10 mA cm^-2 It is 94 mV,which is significantly better than the 187 mV of MoS₂,the Tafel slope is 61 mV dec^-1,the ESCA test C_dl value is 87.6 mF cm^-2,and it has high electrocatalytic stability and thermal stability.In this study,a facile and low-cost method was used to prepare nanoflower-like Zn₂Co-MoS₂/CQDs with high catalytic activity.（2）HER process of powdered catalysts relies on an adhesive to connect with the electrode.There are generally problems such as poor conductivity of the adhesive,low electron transport performance,and easy peeling after long-term use.In order to solve the possible problems of powdered Zn₂Co-MoS₂/CQDs,ZnCo/NF was synthesized by growing nanosheet arrays on nickel foam（NF）,and then MoS₂ was grown in situ to synthesize ZnCo-MoS₂/NF self-supporting electrodes.The overpotential at 10 mA cm^-2 was 89 mV,the Tafel slope was 89 mV dec^-1,and the ESCA test indicated a C_dl value of 89 mF cm^-2.After 66 h of continuous electrolysis,stable HER performance was obtained.In this study,a self-supporting electrode with a hierarchical nanostructure of ZnCo-MoS₂/NF was obtained by a hydrothermal method,which has high catalytic performance for hydrogen evolution.