Preparation Of Iron-Cobalt-Nickel Based Electrode Materials For Electrocatalytic Hydrogen Evolution Reaction Applications

Among many new energy sources,hydrogen energy is considered as a clean and efficient green energy source due to its high energy density and zero carbon emission.The efficient utilization of hydrogen energy requires solving key technical problems such as hydrogen preparation,storage and transportation.Hydrogen production from electrolytic water is a green and sustainable way to produce hydrogen,while the slow hydrogen evolution reaction（HER）kinetics limits its industrial application.Despite the high HER activity of platinum（Pt）-based catalysts,their disadvantages such as scarcity and high cost drawbacks limit their large-scale application.Therefore,the development of non-precious metal catalysts with abundant resources and lower costs is necessary.However,non-precious metal catalysts generally have problems such as low catalytic activity and poor stability.In order to solve these problems,in this paper,several stable and efficient HER catalysts are fabricated based on the combination of iron-cobalt-nickel based compounds and two-dimensional materials with physical properties.The research are as follows:（1）MoS₂,as a typical two-dimensional layered material,has high catalytic activity comparable to that of Pt-based materials.Therefore,a g-C₃N₄/Fe₃O₄/MoS₂ composite electrocatalyst,where the MoS₂-decorated Fe₃O₄ nanospheres are loaded on g-C₃N₄substrates,is synthesized for efficient HER reactions.During the hydrothermal process,MoS₂ nanosheets uniformly disperse on Fe₃O₄ nanospheres,which efficiently prevent the agglomeration of MoS₂,contributing to effective exposion of the active sites,redistribution of the surface charge,and optimization of the hydrogen adsorption kinetics and stability.The g-C₃N₄/Fe₃O₄/MoS₂ exhibited excellent HER performance with an overpotential of 159 m V and a Tafel slope 124.06 m V·dec^-1 at a current density of 10 m A·cm^-2.（2）The limited physicochemical properties of single component materials cannot fully satisfy the requirements of highly active electrocatalyst applications.Therefore,the construction of multi-component composites materials is necesssary.This study prepared a core-shell structured NF/r GO/Ni Mo O₄@Co₃S₄ for efficient HER by a simple two-step hydrothermal method.Wherein,Co₃S₄-nanoparticles-decorated flower-cluster-like Ni Mo O₄nanorod arrays are loaded on NF/r GO substrates.Ni Mo O₄ nanorods,which vertically aligned on the NF/r GO substrate,provide abundant specific surface area and fast charge transfer channels.Co₃S₄ particles decorated on Ni Mo O₄ nanorods provide sufficient electrochemically active sites which well contact with the electrolyte solution.In 1.0 M KOH solution,the NF/r GO/Ni Mo O₄@Co₃S₄ exhibited an overpotential of 40 m V to HER at a current density of 10 m A·cm^-2.（3）Selecting self-supporting substrates with large specific surface area is an effective strategy,to avoid agglomeration of nanomaterials,and improve the structural stability of the materials while increasing their electrical conductivity.In this study,Co Mo O₄ nanosheet structures are first grown on the NF substrate by hydrothermal reaction and calcination process.Then,Ni Se nanoparticles are deposed on NF/Co Mo O₄ by constant potential method to construct NF/Co Mo O₄@Ni Se nanosheet electrode materials with graded layered structures.This nanosheet structure grown on NF substrates provides enough space for mass transfer and fully exposes the active sites.Meanwhile,the self-supported electrode can reduce the indirect contact resistance between the electrocatalyst and the substrate,and promotes the timely release of generated bubbles from the electrode.The NF/Co Mo O₄@Ni Se electrode exhibits excellent HER electrocatalytic activity under alkaline conditions.An overpotential of only 58 m V is required to achieve a current density of 10m A·cm^-2.