Preparation Of Joule Thermal Flash Of Carbon-Supported Transition Metal Catalyst And Study On Its Hydrogen Evolution Performance

With the rapid development of social economy,energy shortage and environmental pollution have become more and more the focus of social attention.In the context of achieving the strategic goals of"carbon neutrality"and"carbon peaking",it is urgent to find a new environmentally friendly clean energy.In recent years,studies have found that hydrogen energy,as a new clean energy,has a high calorific value and the combustion product is only water,which is the best choice to solve energy and environmental problems.Among the many hydrogen production methods,the hydrogen production method of electrolysis of water has attracted widespread attention in recent years.Hydrogen evolution catalysts play an extremely important role in the process of water electrolysis,and transition metal sulfide series catalysts have been widely studied.However,due to the use of binders,such catalysts have large impedance and low stability in the electrolyte,which reduces their catalytic activity to a certain extent.Finding a method that can synthesize hydrogen evolution catalysts in situ,and enhancing their own stability and conductivity on the basis of ensuring high catalyst activity has become a hot issue in the industry.In this thesis,a three-dimensional self-supporting carbon-supported transition metal hydrogen evolution catalyst material was prepared by Joule thermal flash method,which has emerged in recent years.Compared with the traditional hydrothermal method and pyrolysis method,Joule thermal flash method has the characteristics of fast,high efficiency,low energy consumption and low cost.Based on this method,the in-situ synthesis of nanomaterials on carbon cloth can not only solve the problems of large energy consumption and time-consuming traditional synthesis methods,but also eliminate the need for binders,thereby ensuring the excellent conductivity and stability of nanocomposites.It provides a feasible scheme for the efficient preparation of transition metal sulfide hydrogen evolution catalyst.Firstly,a Joule thermal flash experiment platform was built and remote control was realized through supporting software;Based on this experimental platform,a carbon cloth with a three-dimensional structure and strong conductivity is used as the substrate,and the transition metal salt solution is used as the metal precursor.Two novel composites were prepared by Joule thermal flash（FJH）,namely binary transition metal sulfide/carbon cloth（Co Ni S_x/CC）electrode material and high-entropy alloy sulfide/carbon cloth（M₅S_x/CC）electrode material.The microstructure and physical properties of the two composites were studied by means of relevant characterization,and their electrocatalytic hydrogen evolution performance in alkaline electrolyte was studied by electrochemical tests.Then,uniformly dispersed binary transition metal sulfide nanoparticles（Co Ni S_x/CC）were synthesized on carbon cloth materials by Joule thermal flash method.The results of electrochemical experiments show that the composite has good electrolytic hydrohydrogen evolution（HER）catalytic activity.Under the optimal experimental parameters,namely 60m F capacitance and 40V voltage,the required overpotential of Co Ni S_x/CC composites when the current density reaches 10 m A·cm^-2is 112m V.In the alkaline electrolyte of 1 M KOH,the Tafel slope is 162.38 m V·dec^-1,and the commercial 20%wt Pt/C electrode has a Tafel slope of 141.36 m V·dec^-1 and an overpotential of 97 m V under the same conditions.After 1000 cycles of voltammetry test,the overpotential of the catalyst only increased slightly,indicating that it had good stability.At last,in order to further improve the electrocatalytic hydrogen evolution activity of composite electrode materials,M₅S_x/CC,a high-entropy alloy nanocatalyst was successfully synthesized by Joule thermal flash method using carbon cloth as the matrix.In an alkaline solution of 1 M KOH,under the optimal experimental parameters,60m F capacitance and 60V voltage,when the current density is 10 m A·cm^-2,the superpotential of the M₅S_x/CC composite is 115 m V,and the tafel slope is only 136.8m V·dec^-1.After 1000 cycles of voltammetry testing,the hydrogen evolution overpotential of the catalyst increased by only 5 m V.Compared with transition metal sulfides,its conductivity and electrochemical active area are greatly improved.The three-dimensional network structure of the matrix material carbon cloth is conducive to the exposure of the active site and improves the conductivity of the composite.The introduction of sulfur can also adjust the electron density and increase the desorption rate of hydrogen.This thesis proves that Joule thermal flash method and high-entropy alloy materials can be applied to the preparation of hydrogen evolution catalysts,which provides a new idea for the design of efficient hydrogen evolution catalysts.There are 34 figures,7 tables,and 92 references in this thesis.