Preparation Of Copper-coated Silver-based Catalyst And Its Hydrogen Evolution Performance

The problem of environmental pollution and energy shortage is gradually revealed in the world with the increasing population,the developing economy and the continuous progress of science and technology.Hydrogen production by electrolysis of water is an important means to obtain renewable clean energy.Therefore,exploring electrocatalytic materials with high efficiency and low cost is the focus of current research.Electrolyzed water catalytic materials are usually divided into precious metal materials,transition metal materials and non-metallic materials.Catalytic materials with excellent performance usually have the common advantages of high activity,large specific surface area and fast electron transfer rate.Non-metallic materials and transition metal materials have received extensive attention in recent years due to their abundant reserves and cheap production costs.Among them,transition metal phosphides and transition metal selenides are often used as electrocatalysts for water splitting due to their certain catalytic activity and good stability.The development of such electrocatalysts is of great significance in the future application of electrolytic water production.The research situation of this paper is as follows:（1）Ag-Cu precursor material was prepared by electroless plating using Ag powder with good conductivity as the substrate material.Ag-Cu₃P material with catalytic activity was obtained by calcining and phosphating Ag-Cu precursor with appropriate amount of NaH₂PO₂.Subsequently,Ag-Cu₃P particles were mixed with carbon nanotubes for ball milling to obtain Ag-Cu₃P@CNTs catalytic material and prepared as a catalytic electrode.By changing the ratio of Ag-Cu₃P to CNTs,the preparation conditions of Ag-Cu₃P@CNTs with the best catalytic performance were determined.Through physical characterization,it is found that Ag-Cu₃P particles are well combined with CNTs and the surface phosphating degree is high.The performance test shows that when the ratio of Ag-Cu₃P to CNTs is 4:1,the Ag-Cu₃P@CNTs catalytic material exhibits a HER overpotential of 145.1 m V and a Tafel slope of 54.90 m V dec^-1 at a current density of 10 m A cm^-2.The material exhibits long-term stability,and the morphology remains basically unchanged before and after the test.The test shows that the material also has certain OER catalytic activity.The excellent catalytic performance of Ag-Cu₃P@CNTs catalytic material is attributed to the fact that Ag as the substrate greatly improves the conductivity of the material.The heterogeneous interface formed by Cu and Cu₃P on the surface is conducive to the combination of protons and electrons in the HER process to improve the catalytic performance.The multi-layer skeleton structure of carbon nanotubes has a high specific surface area,which provides more attachment sites for Ag-Cu₃P particles with catalytic activity to expose more active sites.（2）The content of Cu on Ag surface can be changed by changing the electroless plating time of Ag-Cu precursor prepared by electroless Cu plating.Ag-Cu₂Se@CNTs catalytic electrode material was prepared by selenization at room temperature and ball milling with carbon nanotubes in a certain proportion.The ratio of Cu to Ag has a great influence on the catalytic performance of the product.The appropriate copper plating time can obtain the best catalytic performance.The results show that when the electroless plating time is 6 min,Ag-Cu₂Se@CNTs has the best electrocatalytic performance.The hydrogen evolution overpotential at 10 m A cm^-2 current density reaches 106.2 m V HER overpotential and 59.20 m V dec^-1 Tafel slope,and the material has excellent catalytic stability.