Preparation Of P-doped Nickel Molybdenum-based Composites And Their Electrocatalytic Properties For Hydrogen Evolution Reaction

With the rapid growth of human demand for energy and the increasingly severe environmental problems since industrialization,it is urgent to find clean energy with abundant storage of raw materials.Therefore,the electrocatalytic hydrogen evolution technology has gradually aroused the interest of scholars because of its abundant raw materials and clean products.At present,Pt-based material is still the best catalyst.However,its high cost limits the development of electrocatalytic hydrogen evolution.The development of efficient and inexpensive catalysts could effectively promote the industrial production of hydrogen.Nickel foam（NF）is one of the most promising non-noble metal materials because of its 3D structure and high activity.Using NF as the carrier,the self-supporting electrode material has many advantages,such as larger specific surface area,faster electron transfer and excellent stability.At present,there are many strategies to optimize the properties of materials,such as the construction of heterojunction and the doping of non-metallic elements.Based on this,the work of this thesis mainly focuses on the preparation of nickel and molybdenum based compound self-supporting electrode and the study of electrocatalytic hydrogen evolution performance.The preparation process of the material and the effect of phosphorus doping on the structure and properties of the material were studied.The main research contents are as follows:（1）The heterogeneous structure of phosphorus doped nickel molybdate/molybdenum dioxide（P-Ni Mo O₄/Mo O₂）composites was prepared by two steps of hydrothermal and heat treatment.Appropriate phosphorus doping can effectively widen the lattice fringe,optimize the electronic structure to accelerate the transport of reactive hydrogen and hydrogen removal,and accelerate the reaction efficiency.On the basis of the above,the effect of heat treatment temperature on the crystallinity of the material was investigated.Too low heat treatment temperature will affect the formation of phase;Too high heat treatment temperature will make the material hard and brittle,affecting the reaction efficiency.When the heat treatment temperature is 400℃,it is beneficial to the performance of the material.When the current density reaches 100 m A cm^-2,the overpotential of the material can reach 353mV,and the Tafel slope is 101.02 mV dec^-1.（2）Oxides are not stable in acidic or alkaline solutions,while transition metal sulfides usually have good corrosion resistance.Based on this,the coaxial heterostructure of phosphorus doped nickel disulfide@molybdenum carbide（P-Ni₃S₂@Mo C）composite material was prepared.The influence of phosphorus doping on the properties of the materials was also investigated.When the amount of phosphorus source is 2 g,the material can achieve better performance.The microstructure and crystalline grain size of the material were controlled by controlling the time of hydrothermal process.The regular morphology and appropriate crystalline grain size are beneficial to the improvement of material properties.When the hydrothermal time is 24 h,the properties of the prepared materials are the best.When the current density reaches 100 m A cm^-2,the overpotential can reach 337 mV,and the Tafel slope is 98.79 mV dec^-1.