Study On Controlled Synthesis And Electrocatalytic Hydrogen Evolution Performance Of CoP Nanomaterials

Transition metal phosphates are promising electrocatalysts because of their similar structure to hydrogenases,abundant reserves and low price.Among them,CoP nanomaterials have the advantages of excellent electrochemical performance and high stability,so it has become a research hotspot in recent years.However,in HER process CoP nanomaterials as an electrocatalyst for hydrogen evolution,the only anion active site caused by the transformation of valence electrons leads to insufficient proton discharge treatment efficiency,resulting in slow electrocatalytic kinetics of CoP nanomaterials and limited catalytic efficiency.In addition,its poor conductivity and dispersion will also affect the hydrogen evolution performance of CoP nanomaterials.In order to solve the above problems,CoP nanomaterials were taken as the research object and modified to obtain non-noble metal high-performance electrolysis aquatic hydrogen catalyst.Firstly,Co-MOFs precursors were prepared using metal-organic frameworks（MOFs）as templates,and CoP nanomaterials were prepared by optimizing the synthesis scheme.The polyhedron with good dispersion and uniform particle size can increase the specific surface area of CoP nanomaterials and expose more active sites,and then achieve the best performance of HER.When using 1:4 Co-MOFs as precursor,phosphating under 350℃,electrochemical performance of the CoP nanomaterials is optimal.In 0.5 M H₂SO₄ acidic electrolyte,when the current density is 10 m A cm^-2,its overpotential(η₁₀)is 469.4 m V,and the Tafel slope value is456.7 m V dec^-1.The current density almost does not change at 10 m A cm^-2 during the continuous water electrolysis for 10 h.Secondly,CoP nanomaterials was modified by anion and cation doping.After modification,the morphology and phase composition of the prepared nanomaterials are basically unchanged.The doping of heterogeneous elements can regulate the electronic structure of the catalysts,thus improving the intrinsic activity of the catalysts.The overpotential(η₁₀)of CoP_xS_1-xnanomaterial doped with anion in acidic electrolyte is 399.4 m V and the Tafel slope is 322.4m V dec^-1.The current density remained at about 10 m A cm^-2 and showed no trend of decline during the continuous electrochemical hydrogen evolution process for 10 h.In the process of cationic modification,it was found that Zn and Fe bimetallic co-doping preparation of Zn,Fe-CoP nanomaterials show optimal electrochemical performance among the electrocatalysts.In the acidic electrolyte,the overpotential(η₁₀)is 107.9 m V and the Tafel slope is 67.2 m V dec^-1.The current density is stable at about 16 m A cm^-2 after 10 h of electrocatalytic hydrogen evolution at a constant potential,showing no trend of attenuation.Finally,the spontaneous redox reaction occurs between Co-MOFs and GO,and the bonding bond provides a faster channel for charge transport and improves the electrical conductivity of the catalyst.In acidic electrolytes,the overpotential(η₁₀)of CoP/GO nanomaterials is only197.6 m V,and the Tafel slope is 199.6 m V dec^-1.The current density of CoP/GO nanomaterials is almost stable at 10 m A cm^-2 during the continuous electrocatalytic process for 10 h,showing high stability.