Modification And Electrochemical Properties Of Fe-Ni Layered Double Hydroxides

In recent years,environmental pollution and energy shortage problems have plagued us all,so we urgently need to find sustainable,clean and efficient ways to obtain energy to solve the global warming problem,thus responding to the national carbon peak carbon neutral.Among the many advanced energy acquisition methods,the oxygen precipitation reaction in electrocatalysis plays a crucial role.Therefore,there is an urgent need to investigate catalysts with excellent catalytic performance that are inexpensive and stable.In this thesis,the catalytic performance of the catalysts for oxygen precipitation was improved by modifying the iron-nickel layered bimetallic hydroxides through sulfur doping and argon plasma treatment to improve the electronic structure and adsorption energy of the catalysts to the reaction intermediates to generate oxygen vacancies on their surfaces.The main studies are as follows:(1)Preparation of sulfur-doped iron-nickel layered bimetallic hydroxides and their application to electrocatalytic oxygen precipitation reactionIn this study,sulfur-doped iron-nickel layered double hydroxides(S-FeNi LDH)were prepared by a one-step method for efficient oxygen precipitation.The catalyst has the advantages of large specific surface area,low overpotential,high stability and simple synthesis.S-FeNi LDH needs 202 mV overpotential to achieve a current density of 10 mA/cm~2in 1 M KOH solution.The catalyst works at a current density of100 mA/cm~2for 20 h,and the voltage remains basically stable,which surfaces the stability of the catalyst.More importantly,the catalyst also has excellent performance in oxygen precipitation in seawater,requiring only 319 mV and 461 mV overpotential to reach 100 mA/cm~2and 500 mA/cm~2in seawater electrolyte,indicating the potential of the catalyst for application in seawater decomposition.The catalyst has a simple preparation method and low preparation cost,and has great potential in the field of new energy.(2)Ar plasma treatment of Fe-Ni layered double hydroxides and application to electrocatalytic oxygen precipitation reactionIn this study,Fe-Ni layered double hydroxides were treated with argon plasma at room temperature to obtain oxygen precipitation catalysts with oxygen vacancies on the surface,high stability and low overpotential.By regulating the argon treatment time,the best catalytic performance was achieved at an argon treatment time of 30 s.A large number of lamellar structures were observed by SEM.The catalyst required an overpotential of 363 mV to reach a current density of 100 mA/cm~2in 1 M KOH solution and was stable for 20 h at a current density of 100 mA/cm~2.The method requires short preparation time and the preparation process is environmentally friendly,which can be of great use in defect engineering.