Preparation And Electrocatalytic Hydrogen Evolution Of Nickel And Modified Carbon Nitride Composite Electrode

At present,due to the increasingly serious global energy crisis and environmental pollution caused by the burning of large amounts of fossil fuels in industrial production,people are urgently looking for new green renewable energy sources to replace non-renewable energy sources such as traditional fossil fuels.Hydrogen is considered to be the most promising new energy source due to its advantages such as environmental protection and high heat of combustion.In the preparation method of hydrogen,producing hydrogen from water splitting via electrocatalysis has attracted much attention due to its abundant raw materials,high yield,cleanness and no pollution.Pt-based metals have high catalytic activity,but their expensive cost and low stability hinder the widespread application of Pt-based catalysts.Therefore,research and development of other highly active,stable and economically feasible hydrogen evolution catalysts are very important.In this paper,a nickel-based composite electrode was prepared by electrodeposition of metallic nickel and modified carbon nitride,and its micromorphology and microstructure were analyzed to investigate its electrocatalytic hydrogen evolution activity.The main research contents are as follows:1.B-doped g-C₃N₄ was prepared by high-temperature pyrolysis and mechanically ball-milled to obtain nanostructures B-C₃N₄?B-C₃N₄-M?,and then Ni/B-C₃N₄-M/NF composite electrode was prepared by co-deposition with nickel on the nickel foam,and its electrocatalytic hydrogen evolution performance was studied.The results showed that compared with the composite electrode prepared by using g-C₃N₄ as the composite phase,the Ni/B-C₃N₄-M/NF composite electrode has excellent electrocatalytic hydrogen evolution performance,and when the concentration of B-C₃N₄-M is 0.2 g L^-1,its Ni/B-C₃N₄-M/NF composite electrode has the best electrocatalytic hydrogen evolution performance.At the current density of 10 and 100 mA cm^-2,the overpotential were 175and 285 mV,and the Tafel slope was 96 mV dec^-1,and has good stability.This is mainly because the addition of suitable concentration of B-C₃N₄-M refine and disperse the nickel particles in the electrodeposition process,thereby increasing the specific surface area of the composite electrode and improving the electrocatalytic hydrogen evolution activity.2.Co-C₃N₄/C with nano-sheet structure was prepared by co-doping with Co and C,and Ni/Co-C₃N₄/C composite electrode was prepared by co-deposition with nickel as composite phase,and different calcination temperatures?600,650,700°C?effect of Co-C₃N₄/C on hydrogen evolution performance of composite electrode.The results show that the Co-C₃N₄/C-650 prepared at a calcination temperature of 650°C is a thin and thin plate-like structure.The Ni/Co-C₃N₄/C-650 prepared by co-deposition with nickel has the best electrocatalysis Hydrogen evolution activity.The electro-catalytic hydrogen evolution activity of Ni/Co-C₃N₄/C-650 composite electrode is mainly due to its high conductivity,large specific surface area,and the synergy between nickel particles and Co-C₃N₄/C-650nanosheets.3.Maintaining a single variable,explore the effects of Co-C₃N₄/C-650 concentration and electrodeposition time on the hydrogen evolution performance of Ni/Co-C₃N₄/C composite electrodes.The results show that when the concentration of Co-C₃N₄/C-650 in the plating solution is 0.3 g L^-1 and the electrodeposition time is 60 min,the prepared Ni/Co-C₃N₄/C-650 composite electrode has the best electrocatalysis hydrogen evolution performance,when the current density is 10 and 100 mA cm^-2,the overpotential is 22 and116 mV,and the Tafel slope is 88 mV dec^-1.Its performance is better than most nickel-based and non-precious metal catalysts,and even similar to the electrocatalytic hydrogen evolution performance of Pt/C.