Preparation And Performance Study Of Efficient Water Oxidation Electrocatalysts Based On Nickel Vanadate

Developing hydrogen economy and reducing energy consumption is one of the important ways to solve the energy crisis.Electrolysis of water is an effective technology to produce high purity hydrogen,but it is severely limited by the oxygen evolution reaction（OER）.In this paper,based on the study of OER principles and factors affecting the OER process,a strategy of constructing heterojunctions to increase the number of active sites is proposed,and two heterojunction catalysts are successfully synthesized and their OER performance is studied.In this paper,Cu（OH）₂ nanowire arrays are grown in situ on copper foam by anodic oxidation,and the Ni₃V₂O₈ nanosheets are loaded on Cu（OH）₂nanowires by hydrothermal reaction,constructing a hierarchical structure for OER in alkaline solution.Firstly,X-ray diffraction and energy dispersive X-ray spectroscopy are used to determine the composition;Secondly,scanning electron microscope is used to observe the morphology.It is found that the electrocatalyst has an overpotential of only317 m V at 100 m A cm^-2 and a Tafel slope of 53.5 m V dec^-1 in 1 M KOH.The sample is tested for 5 h at current densities of 10,20 and 50 m A cm^-2,and no significant decay in catalytic activity is observed.Therefore,it is concluded that a high-performance OER electrocatalyst is successfully prepared by this method.Besides,another electrocatalyst named as Ni₃V₂O₈@Co₃S₄ is successfully prepared on carbon cloth by stepwise hydrothermal method.To investigate whether the electrocatalyst is highly efficient for OER,we apply the same characterization methods and find that the hierarchical electrocatalyst is successfully synthesized by X-ray diffraction,energy dispersive X-ray spectroscopy and scanning electron microscope.During electrochemical test,the electrocatalyst is found to have an overpotential of only270 m V at 30 m A cm^-2 and a Tafel slope of 104.1 m V dec^-1 in 1 M KOH.The stability of the sample is tested for 5 h at current densities of 10,20 and 50 m A cm^-2,and there is no significant decrease in overpotential,indicating that the sample has a good stability.In this paper,two high-performance OER electrocatalysts are successfully constructed by rational use of Cu（OH）₂and Co₃S₄ nanowire arrays,which provides a new idea for industrial and large-scale preparation of efficient and non-precious metal-based OER electrocatalysts in the future.