Design And Electrocatalytic Properties Of Carbon-Based Composite Nano-catalysts For Hydrogen Evolution

Hydrogen energy plays an important role in energy,with high energy density and no pollutants in the combustion and decomposition process,which has attracted much attention from researchers.High purity hydrogen can be prepared by electrolysis of aqua hydrogen technology,which can reduce the energy required for preparation,and there is no pollutant emission,so it is a better hydrogen production technology at present.However,water electrolysis needs to overcome the reaction kinetics barrier in the cathode hydrogen evolution reaction（HER）,which requires efficient and stable electrocatalysts.So far,precious metals and noble metal compounds have been considered as the most effective catalysts for hydrogen evolution.However,although Pt-based precious metal catalysts have great advantages in hydrogen evolution performance,their disadvantages are also obvious.The natural reserves are low,so the price is relatively expensive,and its stability does not have advantages,which greatly limits the large-scale commercial application of catalysts.At present,the development of cheap and efficient catalysts for non-precious metal hydrogen evolution is still needed for energy problems.As we all know,carbon materials have high specific surface area and good stability,showing excellent value in the whole energy system,but pure carbon materials do not have catalytic performance.Therefore,strategies to increase the catalytic activity of catalysts by combining carbon materials with transition metals are of great interest in this area.We prepared different carbon materials and used them to construct carbon-supported transition metal heterojunctions to improve their catalytic activity and stability.In addition,a variety of physical and electrochemical testing methods were used to analyze the performance of the prepared catalyst to explore the effects of its morphology,hydrogenation and defects on the hydrogen evolution performance.The specific results are as follows:1.Using cobalt MOF（ZIF-67）grown on nickel foam as the substrate,a layer of tungsten nitride film was plated on the surface of the MOF by DC magnetron sputtering method,and then the substrate MOF was carbonized by atmosphere sintering furnace to prepare W₂N/nitrogen doped porous carbon（Co-NC@W₂N）composite catalyst,and its electrostatic hydrocracking hydrogen analysis performance was studied.Core-shell morphology,composition,and element distribution were observed by SEM and XRD.It was shown that in a solution of 1 mol L^-1 KOH,the overpotential of the compound catalyst was 55 m V at 10 m A cm^-2 and the Faraday efficiency was 99%.At the same time,Co-NC@W₂N also shows excellent electrochemical properties and good structural stability.2.The 2D high entropy oxides were prepared by Redox reaction and Maillard reaction between glucose and ammonium nitrate,and then annealed and reduced in argon-hydrogen mixture in atmosphere sintering furnace to prepare ultra-thin nano-sheet catalyst with high entropy oxides（HEO_x）with oxygen vacancy and porous carbon.High entropy oxides（HEO_s）rich in oxygen vacancies have the ability to adjust their composition and electronic structure,providing significant stability in corrosive media.The results showed that the overpotential of HEO_x@NF catalyst was 124 m V at 10 m A cm^-2.Compared with high entropy oxides,HER catalytic activity and performance have been greatly improved.In constant current mode,200 m A cm^-2 was stably maintained for more than 12 h.