Study On The Synthesis And Hydrogen Evolution Reaction Catalytic Performance Of Porous Carbon-based Nickel Phosphide Composites

With the development of industrial society,the burning of a large number of fossil fuels has brought serious pollution problems to the environment.As an environmentally friendly fuel,hydrogen has the advantage of high calorific value without producing poisonous gas.Electrolysis of water,as an important method to produce hydrogen,has attracted wide attention in recent years.Among the catalysts for electrolytic water reaction,nickel phosphide has a series of advantages such as low cost and high catalytic activity,but its catalytic performance is restricted by its small surface area and poor conductivity.Therefore,it is important to find a suitable material to increase the surface area of the material and enhance the conductivity.In this paper,two kinds of new composite materials,nickel phosphide/nitrogen-doped porous carbon material and phosphorus doped porous carbon material,are prepared by pyrolysis and hydrothermal method respectively,namely Ni₂P/NC and Ni₂P/PC.They are characterized by a series of experiments,and their properties of electrocatalytic hydrogen evolution in alkaline media are evaluated.First,we use a simple pyrolysis method to load Ni₂P nanoparticles with good dispersion on the nitrogen-doped carbon nanomaterials（Ni₂P/NC）,which has excellent catalytic performance of hydrogen evolution reaction（HER）.Remarkably,the overpotential of Ni₂P/NC composites at 10mA·cm^-2 is 108mV at the optimal ratio.The Tafel slope of the current density at 1 MKOH solution is 67.3mV·dec^-1.After 1000cyclic voltammetry（CV）tests,the overpotential only increased by 4mV.The electrocatalytic performance of the material is better than most similar catalysts in alkaline media.The unique network structure of the carbon component in the catalyst is conducive to the exposure of the active site,reduces the impedance,improves the electron transfer efficiency,and ensures the stability of the hydrogen evolution reaction.In view of the disadvantages of high energy consumption and environmental pollution caused by pyrolysis method.A non-toxic and simple hydrothermal method is used to synthesize dispersed Ni₂P on phosphorous doped porous carbon（PC）.It has excellent catalytic performance for hydrogen evolution reaction.At a current density of10mA·cm^-2,the best Ni₂P/PC material has an overpotential of only 96mV in a 1 M KOH solution,compared with most similar HER catalysts.The Tafel slope is only 77mV·dec^-1.On the other hand,after 2000CV cycles,the hydrogen evolution overpotential of the catalyst increases by only 3mV.As the specific surface area of the porous carbon doped with phosphorus is large,the impedance of the catalyst can be reduced while the active site is increased.In addition,phosphorus atoms in porous carbon can regulate electron density and increase the desorption rate of hydrogen.This experiment proves that the combination of phosphorus-doped porous carbon and Ni₂P nanoparticles is of great significance for hydrogen evolution reaction as a highly efficient catalyst.