Synthesis Of Nickel Foam Self-supporting Water-splitting Electrocatalysts And Their Electrocatalytic Properties

With the continuous development of human society,energy plays a more and more important role in social production and life.It drives economic development and facilitates people’s travel.At the same time,however,we also notice that the traditional fossil energy is increasingly exhausted under the continuous exploitation of human beings,and the large-scale application of traditional fossil energy also brings unprecedented environmental pollution problems.Therefore,develop ing a clean and sustainable energy to replace fossil energy is a subject related to human destiny.Hydrogen（H₂）is regarded as the most potential alternative to fossil energy,because it has the advantages of high energy density,clean and sustainable.In recent years,the preparation of hydrogen from water-splitting device is the most popular topic in the field of energy storage and appli cation.Researchers are committed to developing efficient cathode and anode electrocatalysts to promote the efficient and rapid water-splitting process.Precious metal based electrocat alysts have excellent electrochemical properties,so they have been wide ly concerned,but their high cost and scarcity seriously limit their large-scale application.Therefore,it is of great significance to develop a cheap and efficient transition metal b ased electrocatalyst to promote the rapid development of hydrogen evolut ion reaction（Hydrogen evolution reaction,HER）and oxygen evolution reaction（Oxygen evolution reaction,OER）,so as to improve the efficiency of water-splitting reaction.Commercial foam nickel（Nickel foam,NF）has 3D porous framework and has good electrical conductivity,so it is often used as an electric current collector to build an excellent self-supporting electrocatalyst.The electrocatalyst materials with excellent properties were directly grown on the surface of nickel foam,and their composit ion and morphology were controlled to obtain aligned nanostructured array self-supporting electrocatalysts.Due to the advantages of excellent conductivity,rapid electron and material conduction rate,highly exposed active sites,self-supporting electrocatalysts often have outstanding HER and OER electrocatalysis performance.In this paper,commercial foam nickel（NF）is used as the base material.By adjusting the morphology and elemental composition of the supported catalyst materials,the self-supporting electrocatalysts with excellent morphology and excellent electrocatalytic properties are obtained.Using Co-MOF-loaded nickel foam as a precursor,NiCoP@NC/NF with hierarchical porous and rough surface was obtained through the stepwise calcination and pho sphating process,and then the amorphous NiFe LDH nano-flowers were deposited on its surface to obtain the NiFe LDH/NiCoP@NC/NF catalyst.The chemical measurement method explores the electrocatalytic oxygen evolution performance,electrocatalytic hydrogen evolution performance and the water-splitting performance of the final product.Using nickel foam（NF）as a template,a simple one-step solvothermal strategy is used to prepare uniformly supported on the foam nickel Hetero-ultrathin P doped MoO₃/FeCo LDH nanosheets（denoted as P-MoO₃/FeCo LDH/NF）electrocatalyst,and explore its electrocatalytic oxygen evolution performance.The specific work s are as follows:（1）A hierarchical porous N-doped amorphous carbon-coated NiCoP（denoted as NiCoP@NC/NF）was prepared by gradually calcining and phosphating the organic framework（MOF,ZIF-67）grown on the nickel foam in situ.Then,amorphous NiFe LDH nanosheets were directly electrodeposited on the surface of the NiCoP@NC/NF to form a 3D nano-framework.SEM,TEM,XRD,XPS and other material research methods were used to analyze the micro-morphology and structural composition of the catalyst;using（CV,LSV,EIS,IT）and other electrochemical testing methods to study the electrocatalytic oxygen evolution performance of the NiFe LDH/NiCoP@NC/NF and the hydrogen evolution performance of the NiCoP@NC/NF.This well-designed NiFe LDH/NiCoP@NC/NF electrocatalyst exhibits excellent OER performance due to its special structural characteristics,abundant exposed active sites,and excellent electrical conductivity brought by ZIF-67 derived from NC grown on the nickel foam substrate;efficient electron transfer rate;synergistic effect between NiFe LDH and NiCoP@NC.The resulting hybrid electrocatalyst not only requires a very low overpotential（210 m V）to produce a current density of 10 m A cm^-2,but also exhibits excellent stability.In addition,when the electrocatalyst is combined with NiCoP@NC/NF as a two-electrode system for water-spitting,only 1.54 V is required to obtain a current density of 10 m A cm^-2 in 1 M KOH.This research has successfully improved the OER catalytic activity of LDHs by giving LDHs better conductivity and more active sites,and also opened up a new prospect for designing effective non-precious metal oxygen evolution catalysts to replace precious metal-based electrocatalyst.（2）A simple one-step solvothermal strategy was utilized to prepare a new electrocatalyst of P-doped MoO₃/FeCo LDH ultra-thin nanosheets（denoted as P-MoO₃/FeCo LDH/NF）uniformly supported on nickel foam.SEM,TEM,XRD,XPS and other material research methods were used to analyze the micro-morphology and structural composition of the catalyst and CV,LSV,EIS,IT and other electrochemical testing methods to study the electrocatalytic oxy gen evolution performance of the P-MoO₃/FeCo LDH/NF.Thanks to excellent conductivity,unique homogeneous nanosheet heterostructure,fast electron and mass transfer rate,electronic structure optimized through P-doing and synergistic effect,carefully designed P-MoO₃/FeCo LDH/NF ultra-thin nanosheet heterostructure electrocatalysts exhibit excellent OER performance.In an alkaline medium,only a very low overpotential（225 m V）is required to produce a current density of 10 m A cm^-2,and it also exhibits excellent stability.After 80 hours of constant current test,the electrocatalytic activity does not decay.