Preparation And Electrocatalytic Properties Of Cu-based Catalysts For Oxygen Evolution Reaction

With the rapid development of technology and industry,environmental pollution and energy crisis have sparked increased research pressure for exploring eco-friendly and sustainable energy conversion technologies.Electrochemical water splitting has been regarded as an ideal energy conversion technology,which could convert solar energy,wind energy and other energy sources into hydrogen to be stored and offer a stable supply.In the process of electrochemical water splitting,compare with the hydrogen evolution reaction（HER）on cathode,oxygen evolution reaction（OER）on anode involves complex four-electron transition process,resulting in sluggish OER kinetics and high overpotential,which has become a bottleneck to the development of water electrocatalysis technology.Consequently,it is important to develop OER catalysts with high activity and robust stability.In this paper,Cu S-Ni₃S₂/Cu Ni/NF and Fe₂O₃@Cu O NTs/CF were successfully synthesized by simple methods,and their OER electrocatalyzing mechanism and performance were analyzed.The main contents are as follows:（1）Hydrogen bubble template method was used to in-situ electrodeposit three-dimensional（3D）porous Cu Ni alloy nanodendrite on nickel foam（NF）.And then the surface of Cu Ni alloy was sulphured by hydrothermal method to obtain Cu S-Ni₃S₂/Cu Ni/NF.The 3D conductive Cu Ni alloy with the role of substrate and template provides a large loading area and constructs efficiency electron transport pathway networks,which not only benefits the large exposure of active sites but also facilitates the electron transfer from substrate to active sites.In addition,the result of density functional theory（DFT）calculation demonstrated that the participation of Cu S effectively reduces the energy required for each intermediate to adsorb at the Ni site and increases the electrical conductivity of the catalyst,indicating that Cu S effectively improves OER catalytic activity of Cu S-Ni₃S₂/Cu Ni/NF.Therefore,Cu S-Ni₃S₂/Cu Ni/NF presented outstanding electrocatalytic performance with low overpotentials of 337 and 510 m V to reach 100 and 1000 m A cm^-2 respectively.（2）Copper foam（CF）was used as the substrate and copper source to in-situ grow Cu（OH）₂ nanorods firstly.And then Fe₂O₃@Cu O NTs core-shell nanotube arrays were prepared by using Cu（OH）₂ nanorods as self-sacrificial templates（denoted as Fe₂O₃@Cu O NTs/CF）.The unique nanotube array morphology not only provides a large electrochemical surface area which benefits sufficient contact between electrolyte and active sites,but also supplies a low resistance along their longitudinal direction,promoting the efficient electron transport.Moreover,the electron transfer from Fe₂O₃ to Cu O in the heterostructure modifies the electronic structure of Cu sites and Fe sites,improving electron transfer efficiency and accelerating the OER kinetics simultaneously compared with its single component catalyst,Fe₂O₃ and Cu O.Therefore,Fe₂O₃@Cu O NTs/CF has achieved an enhanced OER activity with a low overpotential of 398 m V to reach 100 m A cm^-2 and a low Tafel slope of 41.07 m V dec^-1.