Synthesis Of Ni-W Electrocatalyst And Study On Its Hydrogen Evolution Performance

In recent years,hydrogen energy has attracted worldwide attention due to its clean and environmentally friendly products,and is regarded as an energy source that can replace non-renewable energy.Hydrogen production by electrolysis of water is a common and effective method,but it is limited because of the serious energy loss in the process.Therefore,finding an efficient hydrogen evolution electrocatalyst is the key to solving the problem.Noble metals such as Pt have very good hydrogen evolution performance as electrocatalysts,but they have their own limitations due to cost issues and cannot be widely used.Therefore,transition metals such as nickel and iron have come into people’s sight.In this paper,a nickel-tungsten alloy electrocatalysts was prepared and its hydrogen evolution performance in alkaline solution was explored.The nickel-tungsten catalyst was synthesized by the constant current deposition on the copper sheet with a DC power supply.The electrochemical data of the catalyst was tested by an electrochemical workstation,the surface morphology was observed by scanning electron microscope(SEM)and transmission electron microscope(TEM),and X-rays were used.Diffraction analysis(XRD)and X-ray photoelectron spectroscopy(XPS)analyze the elements and composition of the sample.The results show that when the electrolyte solution used to synthesize nickel tungsten catalyst is 0.1 mol/L nickel sulfate,0.01 mol/L sodium tungstate,0.08 mol/L sodium citrate,0.2 mol/L sodium chloride,and 0.2 mol/L ammonium chloride,the sample has the best hydrogen evolution performance.The sample has a small impedance value and a low overpotential.The overpotential is only-98 mV at a current density of 10 mA/cm~2,and it is continuously tested in a 1 mol/L KOH solution for 20 h,and it remains stable.It is calculated by the electric double layer capacitance.The electrochemically active area is as high as 769 cm~2.From the perspective of various characterization methods,the nickel-tungsten catalyst is a replacement solid solution with nickel as a solvent and tungsten as a solute,forming a porous structure on the surface.In summary,nickel-tungsten catalysts have excellent hydrogen evolution performance,which provides new ideas for the research of electrocatalysts.On the basis of the above,continue to use SEM and XRD to explore the content of tungsten and sodium citrate in the electrolyte,as well as the influence of the introduction of cobalt on the original catalyst,and test and compare the corresponding hydrogen evolution performance.As the tungsten content in the electrolyte increases from scratch,the surface of the sample has always maintained a porous structure.The flower shape of the catalyst is basically retained but the petals gradually become thicker,resulting in a decrease in electrochemical active area.With the increase of sodium citrate in the electrolyte,the surface of the sample gradually changed from a pit to a porous structure,and the catalyst grew from a spherical shape to a flower-like structure,and the hydrogen evolution overpotential first decreased and then increased.When the cobalt element is introduced into the electrolyte and the cobalt content is 0.01 mol/L,compared with the original catalyst,the Ni-W-Co alloy has the same morphology and electrochemically active area.And the hydrogen evolution overpotential only increased by 5 mV.As the cobalt content continues to increase,the catalyst grows into a spherical shape,and a large number of clusters are deposited on the surface of the sample,which gradually fall off,resulting in poor hydrogen evolution performance.