Study On Performance And Preparation Of Transition Metal Phosphides For Hydrogen Evolution In Electrolyzed Water

People’s excessive dependence on fossil fuels makes the limitations of the energy structure increasingly prominent.As an ideal clean energy carrier,hydrogen is considered to be one of the most promising alternatives to fossil fuels,playing an increasingly important role.Using the renewable energy to produce hydrogen from water electrolysis is a sustainable and scalable method and is considered to be the most promising hydrogen production technology.The catalyst has a great influence on the efficiency of water electrolysis.Reducing the overpotential of electrolysis and increasing the reaction rate of the kinetic electrode are of great significance for improving the efficiency of electrolysis.At present,for the hydrogen evolution reaction,the most effective catalyst is the noble metal Pt-based material,but the high cost and low reserves of Pt greatly limit its wide application in large-scale hydrogen production technology.Therefore,the development of non-noble metal catalysts with high efficiency,low cost and good stability is of great significance.Transition metal phosphides are known as "quasi-platinum catalysts" hydrogen evolution catalysts due to their stable structure,good electrical conductivity and thermodynamic stability.They are the frontier research hotspots of non-noble metal hydrogen evolution electrocatalysts at home and abroad.The research content of this article is as follows:(1)The metal precursor supported on graphene was synthesized by the impregnation method,and then the NiCoP,CoMoP,MoNiP bimetal phosphide nanocomposite catalyst supported on the graphene nanosheets was synthesized by gas-solid phosphating.Through characterization,it is found that the introduction of graphene support makes the catalyst particles dispersed well without agglomeration.The polarization curve,Tafel slope,electrochemically active surface area,electrochemical impedance and stability were tested in 0.5 M H2SO4 solution by the rotating disk electrode.The study found that the NiCoP/GR catalyst exhibited the best HER catalytic activity.In the 0.5 M H2SO4 electrolyte,NiCoP/GR catalyst,which delivers an overpotential of 195 mV for HER and exhibits the lowest Tafel slope of 66.4 mV dec-1 at the current density of 10 mA cm-2.Additionally,the NiCoP/GR catalyst shows good stability after 12 h.(2)The Ni-Co precursor grown on nickel foam was synthesized by hydrothermal method.And then NiCoP/NF catalysts with Ni/Co ratios of 0:4,1:3,2:2,3:1,4:0 were successfully prepared by gas-solid phosphating method.The polarization curve,Tafel slope,electrochemically active surface area,electrochemical impedance and stability were tested in 1.0 M KOH solution.The study found that the morphology of NiCoP/NF catalysts with the different Ni/Co ratios changed significantly after phosphating.As the ratio of Ni/Co decreases,the degree of integrity of the NiCoP/NF catalyst precursor structure first increases and then decreases.In alkaline conditions,as the ratio of Ni/Co decreases,the HER catalytic activity of the NiCoP/NF catalyst first increases and then decreases.The NiCoP/NF 1-3 catalyst with a Ni/Co ratio of 1:3 has the best HER catalytic performance.In the 1 M KOH electrolyte,the NiCoP/NF 1-3 catalyst with a Ni/Co ratio of 1:3,which only delivers an overpotential of 99 mV for HER and exhibits the lowest Tafel slope of 65.44 mV dec-1 at the current density of 10 mA cm-2.Additionally,the NiCoP/NF(Ni/Co,1:3)catalyst shows good stability after 20 h.