Preparation Of Ni-based Phosphide/Hydroxide Heterostructure And Study On Its Electrocatalytic Hydrogen Evolution Performance

With the consumption of a large amount of fossil fuels in the process of industrialization,the problem of environmental pollution has become increasingly serious.At the same time,the development of clean and sustainable energy is also receiving more and more attention.As a renewable energy,hydrogen is an ideal fuel to replace fossil energy.Electrocatalytic water splitting is one of the most promising methods to produce hydrogen in a sustainable and environmentally friendly way.We need an effective and stable electrocatalyst to reduce the overcharge of the electrocatalytic hydrogen evolution reaction（HER）and accelerate the reaction process.Platinum and platinum-based precious metals are considered to be the most effective electrocatalysts in the electrocatalytic HER.However,platinum is expensive and scarce,which limits its application in industrial hydrogen production.Therefore,it is of great significance to find an electrocatalyst with lower cost and excellent hydrogen evolution performance to replace platinum-based catalyst materials.Transition metal phosphides（TMPs）have been widely studied for their excellent electrical conductivity and HER electrocatalytic activity.Negatively charged P acts as a proton acceptor,weakening the bonding strength of the metal（positively charged hydride acceptor is M-H）,which promotes the desorption of hydrogen.Compared with platinum-based noble metal catalysts,the HER electrocatalytic performance of transition metal phosphides is still poor.In particular,the HER performance of nickel phosphide（Ni₂P）under alkaline conditions is limited due to the slow initial hydrolysis process.Based on this,this article takes Ni₂P as the main research object to carry out related experiments on improving the HER performance of Ni₂P under alkaline conditions.1.Using a simple hydrothermal synthesis method,Ni（OH）₂ nanosheet precursors are prepared on the surface of nickel foam,and then phosphating compounds with different phosphating degrees are prepared by controlling the phosphating temperature（Ni₂P@Ni（OH）₂/NF-1,Ni₂P@Ni（OH）₂/NF-2,Ni₂P/NF）.Among them,Ni₂P@Ni（OH）₂/NF-2 in 1.0 M KOH solution,the overpotential required to reach a current density of 10 m A cm^-2 is 110 m V,and the corresponding Tafel slope is 63.5m V dec^-1.The research results show that,thanks to the synergistic effect of Ni₂P and Ni（OH）₂,Ni₂P@Ni（OH）₂/NF-2 obtained by phosphating at 350°C has the best HER performance.2.In addition,we use a simple dipping method to effectively combine the Ni₂P@Ni（OH）₂/NF-2 heterostructure with a small amount of precious metal Ru（represented as Ru-Ni₂P@Ni（OH）₂/NF-2）.Ru is reduced on the surface of Ni₂P@Ni（OH）₂/NF-2 through spontaneous redox reaction.The Ni₂P@Ni（OH）₂/NF-2heterostructure shows excellent HER activity.In 1.0 M KOH solution,the overpotential required to reach a current density of 10 m A cm^-2 is 31 m V,and the corresponding Tafel slope is 27.8 m V dec^-1.The results show that the surface of Ni₂P@Ni（OH）₂/NF-2 modified by Ru is more conducive to the adsorption of H_ad and the generation of H₂.