The Research On Preparation And Electrocatalytic Hydrogen Evolution Reaction Of Nickel-cobalt Based Sulphide Composite Electrode Materials

In order to solve the problems of energy shortage and environmental pollution,it is very important to popularize electrolytic water hydrogen production technology.However,at present,the hydrogen production from electrolytic water is restricted by the large polarization of the electrode and the slow reaction kinetics,which makes the energy consumption of hydrogen preparation high and the conversion efficiency low.In the process of electrocatalysis,electrode material is the medium of electron transfer and the site of catalytic reaction.It is imperative to develop efficient and cheap cathode electrode materials to reduce hydrogen evolution overpotential.This paper aims to effectively modify nickel-cobalt-based sulfides and their composite electrode materials through mesoporous introduction,structure control,surface modification and other regulatory methods,in order to obtain a more efficient hydrogen evolution electrode interface.The main research contents and results are as follows:1.The nano-porous Ni-Co alloy was prepared by rapid solidification and dealloying,after vapor deposition of sulfur and hot hydrogen reduction,the nano-porous Co₉S₈/Ni₃S₂composite electrode materials with surface mesoporous defects were prepared.Studies have shown that through vapor deposition,sulfur atoms and Ni-Co alloys in situ form CoS₂/Ni S₂composite phases,and after thermal hydrogen reduction,Co₉S₈/Ni₃S₂composite phase with a low sulfur atom ratio is formed.This thermal hydrogen reduction process not only increases the electron density around the Co₉S₈/Ni₃S₂elements,but also modulates the interhole structure on its surface.Then the electron transport capacity is improved(R_ct=1.064?·cm^-2)and the active surface area is increased(BET=20.2 m²/g?C_dl=16.66 m F·cm^-2).Compared with other Ni and Co sulfides that prepared under the same conditions,Co₉S₈/Ni₃S₂have better HER activity.At a current density of 50 m A·cm^-2,the hydrogen evolution overpotential of Co₉S₈/Ni₃S₂is 234 m V,and the Tafel slope is106 m V·dec^-1.After CV cycles stabilization test,the voltage changes only 14 m V.2.The nano porous Ni-Co alloy was prepared by same method.Then bimetallic sulfide NiCo₂S₄and its composite electrode materials were prepared by regulating the process temperature of vapor deposition of sulfur.The study shows that the CVD preparation temperature of NiCo₂S₄is about 550?,and the hollow spinel type NiCo₂S₄/Co₃S₄/CoS composite electrode material is formed at 750?.The bimetallic sulfide composites NiCo₂S₄/Co₃S₄/CoS not only increase the unit volume area due to the hollow thin shell structure,but also form rich nano-coupled interface between three compounds,which provide more reaction sites(C_dl=21.35 m F·cm^-2)and active site points(Ea=23.38 k J·mol^-1)for hydrogen evolution reaction.At 50 m A·cm^-2current density,The hydrogen evolution overpotential of NiCo₂S₄/Co₃S₄/CoS is 221m V,and the Tafel slope is 104 m V·dec^-1,but it stability is slightly inferior than NiCo₂S₄.3.On this basis,Ru and Ru S₂which have excellence intrinsic catalytic activity were adhered to NiCo₂S₄surface by solvothermal method.Meanwhile,the Ru content was regulated to prepare the best structure of NiCo₂S₄/Ru.Research shows that,When Ru(wt/%)=60%,The simple Ru forms the best three-dimensional network flake structure coated on the NiCo₂S₄surface.based on three-dimensional network nano flake structure and material surface modification,The reactive active area(C_dl=27.6m F·cm^-2)and electron transfer ability(R_ct=0.487?·cm^-2)are increased.At 50m A·cm^-2current density,The hydrogen evolution overpotential of NiCo₂S₄/Ru(60%)composite electrode materials is 70 m V,the Tafel slope is 76 m V·dec^-1,These electrocatalytic properties are much better than NiCo₂S₄/Ru S₂which has Same Ru content.And during the continuous electrolysis of 10 m A constant current,the voltage of NiCo₂S₄/Ru(60%)changs around 10 m V,it shows good electrocatalytic hydrogen evolution activity and excellent stability.