Efficient Oxygen Evolution Electrocatalyst:Preparation Of Transition Metal-based Heterostructure Array And Performance

With the consumption of fossil fuels and the increasingly serious environmental problems,the development of new energy sources is imminent.Electrolyzed water consists of hydrogen evolution reaction（HER）and oxygen evolution reaction（OER）and is one of the most promising hydrogen production methods.Among them,the multi-electron,multi-step process in OER leads to the slow kinetics of its oxygen production process,which limits the further development of electrocatalytic water decomposition.Exploring the preparation of efficient and durable OER electrocatalysts is of great significance for reducing the overpotential and improving the efficiency of hydrogen production from electrolyzed water.The heterostructure array material introduces a heterogeneous interface or a heterostructure array on the surface of the conductive substrate,which changes the electronic structure of the catalyst and adjusts its surface properties,provides a wealth of active sites,and improves the OER activity and stability of the electrocatalyst.It is an important way to develop OER catalyst.This paper explores the preparation,characterization and OER performance control of different types of transition metal compound heterostructure array catalysts.Studies have shown that the synergy between metal compounds in heterostructures can effectively enhance the electrocatalytic performance,which provides an effective strategy for further research on cheap electrode materials for electrolyzed water.（1）We report the rational design and preparation of a new type of high-performance oxygen evolution electrocatalyst--3D heterostructured Co₃O₄@Ni Mn-LDH arrays supported on Ni foam（Co₃O₄@Ni Mn-LDH/NF）.It was prepared via facile two-step hydrothermal reactions.Compared with Co₃O₄,Ni Mn-LDH and traditional Ru O₂electrocatalysts,the as-prepared Co₃O₄@Ni Mn-LDH/NF presents better electrocatalytic oxygen evolution performance,achieving a low overpotential of 282 m V at 50 m A cm^-2with a Tafel slope of 64 m V dec^-1in 1.0 M KOH solution.Through effective interface engineering design,the Co₃O₄@Ni Mn-LDH/NF combines synergistically the excellent electrocatalytic activity of Co₃O₄and Ni Mn-LDH.The Co₃O₄nanowire array based on Ni foam as a core structure with abundant void spaces not only exposes more active sites,but also ensures easy diffusion of electrolyte and fast release of gas products.And the Ni Mn-LDH nanosheets on the Co₃O₄nanowire array provide rich hydrophilic groups and active sites for easy access of water molecules,thus facilitating efficient oxygen evolution reaction.（2）Through a method involving hydrothermal and calcination processes,a heterostructure Co₃O₄@Co Mo O₄nanoarray was designed and synthesized on nickel foam（NF）.Using XRD,XPS,TEM,FESEM and other means to characterize the structure and composition of the material,and carried out electrochemical performance tests.The results show that the Co₃O₄@Co Mo O₄nanoarray catalyst material has excellent OER performance.Co₃O₄@Co Mo O₄achieving a low overpotential of 252 m V at 50 m A cm^-2with a Tafel slope of 59 m V dec^-1in 1.0 M M KOH solution.The experiment explored the influence of the growth time of Co Mo O₄on the electrochemical performance of the catalyst for oxygen evolution reaction.When the growth time is 8h,the electrochemical performance is the best.As a catalyst for oxygen evolution reaction,it has a good application prospect.