Construction And Hydrogen Evolution Performance Of CoSe₂/C Composite Electrode

Hydrogen is considered as a sustainable clean energy due to its high energy density,cleanness,and renewability.Hydrogen production by electrolysis of water is the most direct and clean method.The most efficient electrocatalysts for hydrogen evolution reaction（HER）are noble metal platinum-based catalysts.However,due to its small reserves,high price and poor long-term cycle stability,it is not conducive to large-scale applications.Therefore,there is an urgent need to develop efficient and durable electrocatalysts for hydrogen production from low-cost transition metal compounds.In recent years,CoSe₂ has been widely studied due to its unique properties as a transition metal selenide.However,CoSe₂ has the problems of easy agglomeration and low electrical conductivity,which limit its development as an electrocatalyst for hydrogen evolution.In order to solve this problem,two kinds of CoSe₂/C based composites were designed and prepared in this paper,and their electrocatalytic hydrogen evolution performance was analyzed.The main research contents are as follows:（1）First,Co（OH）F nanowire arrays were hydrothermally generated using carbon cloth as a conductive substrate,and then self-supporting CoSe₂/CC-B composites were prepared by annealing selenization method.The structure of this electrode has the advantages of increasing the penetration of the electrolyte and promoting the escape of H₂ bubbles.The CoSe₂/CC-B composite enhanced the catalytic activity of a single active site with an overpotential of 193 m V and a Tafel slope of 54.3 m V dec^-1 when the current density reached 20 m A cm^-2.The HER activity was significantly improved after 6000 CV cycles and could be maintained in the 24 hours durability test.（2）CoSe₂/CNTs composites were obtained by in situ growth of CoSe₂ nanoparticles on the surface of carbon nanotubes（CNTs）by a simple one-step hydrothermal method.Compared with pure CoSe₂,the CoSe₂ nanoparticles of the composite were reduced in size and dispersed more uniformly,exposing more active sites.The introduction of CNTs not only accelerated electron transfer and ion diffusion,but also improved the reaction kinetics of HER by forming a CoSe₂/CNT heterointerface.When the mass ratio of CoSe₂to CNTs is 10:1,the CoSe₂/CNTs composite exhibits an overpotential of 153 m V and maintains good stability for 48 hours with negligible overpotential decay.The Faradaic efficiency can reach 97.67%and the H₂/O₂ molar ratio is 2:1.