Investigate The Effect Of Strain On CoP’s Hydrogen Evolution Ability By Using The Method Of Density Functional Theory Calculation

While fossil fuels alleviate energy demand,they cause serious environmental pollution and global warming.Therefore,it is increasingly urgent to develop clean,efficient and renewable new energy sources to replace fossil fuels.Hydrogen energy has attracted extensive attention because of its high energy density and high calorific value of combustion.Among various hydrogen production technologies,the process of producing hydrogen by electrolysis water is simple,and the products are hydrogen and oxygen,which have no pollution to the environment.Therefore,it is regarded as the most promising way to produce hydrogen.Electrolysis of water to produce hydrogen mainly consists of two half reactions,cathodic hydrogen evolution reaction(HER)and anodic oxygen evolution reaction(OER).In the hydrogen evolution reaction,for now the most commonly used and the best catalysts of catalytic performance are mainly precious metals such as Pt.However,precious metal catalysts have defects such as high price and scarcity.Considering that the hydrogen energy demand increases significantly in the future,and that hydrogen production cost requirements under the trend become increasingly tight,people have to find suitable catalysts to replace noble metal catalyst,so as to be used in a wide range of industrial hydrogen production.Recently,transition metal phosphides(TMPs)have attracted more and more attention due to their advantages of low cost,good catalytic performance and wide sources.However,compared with noble metal catalysts,the catalytic performance of transition metal phosphide catalysts is still lower.Therefore,in this paper,the influence of strain on the catalytic performance of transition metal phosphating catalyst was studied by applying strain to the surface of transition metal phosphating catalyst.In this paper,the Gibbs free energy of hydrogen-evolution reaction on the catalyst surfaces was calculated by using density functional theory to characterize the catalytic activity of hydrogen-evolution reaction on the catalyst surface.It mainly includes the following steps.(1)Cobalt phosphide,a classic transition metal phosphide,was selected for the study.Different surfaces of cobalt phosphide were calculated respectively.The surfaces with low Gibbs free energy(111)and(101)were selected as the research objects of this study.The Gibbs free energy at two surfaces with different hydrogen atom adsorption concentrations was calculated.(2)We apply different levels of strain on cobalt phosphide(111)surface and(101)surface,respectively.We calculate hydrogen evolution reaction Gibbs free energy under different hydrogen adsorption concentrations on the surfaces,and compared with Gibbs free energy of the strained surfaces.The data show that applying proper strain on the surfaces of cobalt phosphide can greatly improve their catalytic properties in the hydrogen evolution reaction.(3)Through the treatment and analysis of the experimental results,it is proposed that the influence of surface strain on the catalytic performance of the catalyst is determined by the combination of atomic effect and electronic effect.The surface strain changes the distance between the atoms and the amount of charge they carry,resulting in a change in the strength of the surface interaction with the adsorbed hydrogen atoms.By applying surface strain,the catalytic activity of transition metal phosphide catalyst can be well regulated,which lays a good foundation for the development of hydrogen energy.