Morphology Engineering And Electronic Reconfiguration Of Nickel Phosphide For Overall Water Splitting

With the rapid growth of energy demand,it is urgent to explore green renewable energy.Hydrogen energy,as the focus of energy development in the future,is favored for its outstanding performance of environmental protection and high energy density.The preparation of hydrogen from electrolyzed water is an important direction of hydrogen energy development,and the urgent problem to be solved in electrolyzed water is the selection of electrocatalytic materials.The common electrocatalytic water catalysts are based on Pt/C,RuO₂ and IrO₂ obtained from precious metal materials.Due to the rare reserves and high prices,it is not suitable for large-scale production and use,so it is particularly important to find new efficient and cheap catalytic materials.In this paper,nickel phosphide as the center of research and discussion from three main directions:single phase nickel phosphide material research;heteroatom optimization of nickel phosphide material research;and graphene material and nickel phosphide composite structure research.On this basis,the electrochemical properties,microstructure and reaction kinetics of the materials were analyzed by various analysis methods.The main conclusions are as follows:1?Ni₅P₄/NF catalytic electrode was prepared by hydrothermal method without binder and Ni foam.When the current density is 10 mA/cm²,Ni₅P₄/NF has a HER overpotential of 64 mV and an OER overpotential of only 1.51 V,showing high HER and OER electrocatalytic activity.The composite structure of foam nickel and catalyst provides a shorter reaction path to increase the conductivity of materials and enhance the material exchange between electrolyte and catalyst.At the same time,the composite electrode structure has high stability.2?Mo-Ni-P ternary electrocatalyst was prepared by hydrothermal method.Theoretical calculation shows that the introduction of Mo reduces the reaction energy barrier,changes the electronic configuration of a single nickel phosphide material,and has a stronger electronic capture ability.The synergistic effect between Mo and Ni accelerated the electrocatalytic reaction.The honeycomb spherical structure provides abundant pores and active centers,which is conducive to the infiltration of electrolyte and material exchange in the reaction process.The results show that the catalyst has high efficiency in acid,alkali and neutral electrolyte,especially in alkaline condition.In the durability test,it can work stably for 100 hours,and the crystal structure and micro morphology of the material remain unchanged.3?The metal phosphide/graphene composite was prepared by the combination of microwave and phosphating.The catalyst loaded on the graphene surface was nanoparticles with a diameter of about 10 nm.The rare earth element?Ce?was introduced to obtain Ce-NiP/rGO.The composite has high conductivity of graphene,and the introduction of rare earth Ce makes the strong synergistic effect between Ce and Ni metal cations play an important role in the catalytic process.When the current density is 10 mA/cm²,the overpotential of hydrogen evolution and oxygen evolution is 78 mV and 1.50 V respectively,and it shows very high stability?72.3%?.Due to the homogeneous dispersion of active substances on the surface of graphene,and based on graphene material as the carrier,the electrocatalytic performance of the material can be effectively exerted.