Research On Modification Of Vanadium Disulfide And Water Splitting Performance

Hydrogen energy is considered as a superb and potential fossil energy substitute because of its high combustion calorific value and environmentally friendly and pollution-free products.Electrochemical production of hydrogen from water splitting stands out from many hydrogen production technologies because of its high purity and efficiency.Catalysts represented by precious metals cannot meet the needs of industrialization due to their small reserves and high prices.Vanadium disulfide,as a representative of non-noble metal sulfide catalysts,has metallicity and shows good catalytic performance for water splitting.But it still has the deficiency of high overpotential and low electrolysis efficiency,and its performance still needs to be further improved.In this work,with the goal of preparing high-efficiency overall water splitting catalysts based on vanadium disulfide,a Co-doped vanadium disulfide on nickel foam（Co-VS₂/NF）was prepared by hydrothermal method,and a Co-VS₂@Mo S₂/NF heterostructure catalyst was further constructed.The mechanism of the catalyst was explained by the characterization of the microscopic morphology,microstructure and electrochemical performance.The main results are as follows:1)The Co-VS₂/NF catalyst was prepared by hydrothermal method.The rod-like morphology and crystal structure of VS₂ are not changed after Co doping,and no second phase is formed.The catalyst with Co content of 5%has the best electrochemical performance,and it reveals a low hydrogen evolution overpotential of 164.5 m V at 10 m A cm-2,and small Tafel slope of 52.2 m V dec-1;the oxygen evolution overpotential of Co-VS₂/NF-2 at100 m A cm-2 is 340.6 m V.As a bifunctional electrode for overall water splitting,the cell voltage required at 10 m A cm-2 is 1.71 V,and it shows good catalytic stability.2)The Co-VS₂@Mo S₂/NF heterostructure catalyst was prepared by hydrothermal method.The electronic interaction and synergistic effect between Co-VS₂ and Mo S₂ optimize the interface electronic structure,and the catalyst has a larger electrochemical active area,richer active sites and faster electron transfer rate,showing more excellent electrocatalytic performance.The hydrogen evolution overpotential of Co-VS₂@Mo S₂/NF at 10 m A cm-2 is 73.4 m V,and the Tafel slope is 47.7 m V dec-1;the oxygen evolution overpotential of Co-VS₂@Mo S₂/NF at 100 m A cm-2 is 288.6 m V.As a bifunctional electrode for overall water splitting,the required cell voltage is 1.53 V at 10 m A cm-2,and it exhibits good catalytic stability.