Preparation Of Ni_0.2Mo_0.8N Composite Material And Electrocatalysis Application In Hydrogen Evolution Reaction

Ni-Mo bimetallic nitride has an electronic structure similar to the Pt,as well as excellent electrical conductivity and good corrosion resistance.It has been becoming one of the most expected materials to replace precious metals for hydrogen production by electrolysis of water.However,the typical method for synthesize Ni-Mo nitrides was react with N₂/H₂ or NH₃ under high temperature and high pressures.This method require higher strict condition and safety hazards was released in the meantime.Therefore,it is of great significance to develop a nickel-molybdenum bimetallic nitride with high catalytic activity prepared under mild conditions.In this paper,we used melamine as a solid nitrogen source to prepare a completely nitrided nickel-molybdenum bimetallic nitride under a mild condition.Adjust the electronic configuration by compound doping and other methods to improve the catalytic activity.The material is characterized by XRD,SEM,TEM,Raman and other means,revealing the relationship between the phase structure,morphology and properties of the material.Through the study of the systematic relationship between material design,structure,properties and electrocatalytic performance,explore the ways and conditions that promote the effective hydrogen evolution of materials and synthesize specific morphologies,explain the microscopic mechanism of material formation,and the regulation of structure on performance.The nickel-molybdenum bimetallic nitride(C/Ni_0.2Mo_0.8N@Ni/NF)with carbon-coated nickel segregation was prepared on the nickel foam by a two-step method using nickel foam as the nickel source and ammonium molybdate as the molybdenum source.Guided by improving the performance of electrocatalytic hydrogen evolution,the preparation processes such as the ratio of nickel to molybdenum,the amount of solid nitrogen source,and the nitriding temperature have been optimized.When the ratio of nickel to molybdenum of the front driver is 4:7,the catalyst obtained by reacting with 0.8g of melamine at 600℃has the highest catalytic hydrogen evolution performance.At the current density of 10mA·cm^-2and 100mA·cm^-2,the overpotential are 23mV and 112mV which are much smaller than most of the catalysts that have been reported for hydrogen electrolysis.Under alkaline conditions,hydrogen evolution continues for 48hours.After 1000 cycles of CV cycle,it still shows excellent stability.The reason for its high activity is mainly due to the charge transfer between the segregated nickel element and the matrix can change the electronic structure of the metal,affect the adsorption behavior of the metal,and facilitate the catalytic process.Ni_0.2Mo_0.8N,Mo₅N₆,MoNi₄ layered heterostructures（C/Ni-Mo-N/NF）were grown in situ on the nickel foam using nickel foam as the source of nickel and ammonium molybdate as the source of molybdenum.The influence of the structure,morphology and the performance of hydrogen electrolysis were explored such as the nitriding temperature and the amount of solid nitrogen source.The prepared C/Ni-Mo-N/NF catalyst has an overpotential of 103.72mV when the current density is 10mA·cm^-2,and the Tafel slope of the sample is only 118.83mV·dec^-1,which has relatively excellent electrocatalytic hydrogen evolution activity.The sample continued to evolve hydrogen for 48 hours under alkaline conditions,and after 1000 cycles of CV cycle,it also showed good stability.In-situ growth on the three-dimensional nickel foam conductive substrate can not only solve the problem of incomplete contact between the electrode substrate and the active catalyst,but also reduce the charge transfer resistance,simplify the electrode preparation process,and improve the durability of the electrode.