Preparation Of Electrocatalyst With Heterointerface And Its Application In The Catalysis Of Alkaline Hydrogen Evolution Reaction

Water electrolysis is considered as one of ideal hydrogen production methods with the advantages of renewable raw materials,zero carbon emission and high hydrogen purity.Hydrogen evolution reaction（HER）is the key reaction of water electrolysis.Pt-based materials have high catalytic activity for HER.However,the high cost and scarcity of Pt limit its adhibition.Hence,the development of noble metal-free catalysts with high efficiency and low cost is of great significance to the large-scale utilization of water electrolysis.In this paper,the Co P/Mn O_x and Ni/TiO₂ heterostructure catalysts were prepared by phase separation method to catalyze alkaline HER,and the structure-activity relationship and reaction mechanism were studied in detail.1.The bimetallic oxide MnCo₂O_4.5 was separated into a heterointerface（Co P/Mn O_x）composed of crystallized Co P and amorphous Mn O_x by phosphorization.Compared with Co P,Co P/Mn O_x showed better catalytic activity for alkaline HER.The results showed that the interface effect and grain refinement effect in Co P/Mn O_xcomposites were the main reasons for its high HER performance.The interface effect between Co P and Mn O_x was beneficial to promote the dissociation of H₂O molecules and accelerate the HER kinetic process.During the phase separation of Mn Co₂O_4.5,the existence of Mn O_x could limit the growth of Co P grain,and the reduction of Mn Co₂O_4.5grain size also contributed to the reduction of Co P grain size.The refinement of Co P grain increased the electrochemical active area and heterointerfaces,resulting in the improvement of catalytic activity.2.The phase separation method was used for constructing a heterostructure composed of metallic Ni nanoparticles and rutile TiO₂ with carbon paper as the electroconductive matrix（Ni/TiO₂-CP）.The experimental and DFT calculation consequences showed that the interface interaction between Ni and TiO₂ could induce charge redistribution and change the electronic structure of Ni,thus optimizing the adsorption of water molecules and reducing the energy barrier of water decomposition process.In addition,the oxygen site in TiO₂ had moderate hydrogen adsorption energy,which was used as reactive site for hydrogen adsorption and desorption.Under the interaction of interfacial electronic effect and synergistic effect,Ni/TiO₂-CP exhibited excellent hydrogen evolution performance.In 1 M KOH,the overpotential of Ni/TiO₂-CP at 10 m A cm^-2 is only 28 m V.In addition,the high conductivity of carbon paper also played an essential role in the performance of Ni/TiO₂-CP.