The Study Of Two-dimensional Nanoscale Transition Metal Compounds Defect Construct And Its Electrocatalytic Performance

Electrocatalytic reactions have been widely used in energy devices and electrochemical sensors,among which high-performance electrocatalysts can effectively improve the reaction efficiency,which is the key factor of the technology.Defects can change the electronic structure,affect the absorption,desorption and activation energy of the catalyst to the electrocatalytic reaction species,and then affect the catalytic activity.In this paper,two-dimensional nano-transition metal compounds were selected as the model catalyst,and the structure-activity relationship between the defects and the electrocatalytic performance was systematically studied by using a simple defect construction method.The high efficiency electrolytic water and non-enzymatic glucose detection performance was achieved,which provided a reference for the design and development of high-performance electrocatalysts.（1）In view of the complexity of defects,the structure model of molybdenum disulfide vacancy defects,Fe,Co,Ni,O doping defects and the composite structure of molybdenum sulfide and graphene was constructed.The configuration,charge distribution,Gibbs free energy,state density and band structure of H*adsorption in the defect system were systematically studied by theoretical calculation.The intrinsic mechanism of improving the electrocatalytic hydrogen evolution reaction activity of Mo S₂ by introducing defects was analyzed,which directed the subsequent experimental work.（2）At room temperature,oxygen doping is achieved on the surface of Mo S₂ with abundant edge defects by nitric acid etching.The results show that the addition of defect sites and oxygen doping can regulate the electronic structure of molybdenum sulfide,improve the electrical conductivity of the catalyst,and effectively increase the catalytic active sites,and the catalyst exhibits excellent hydrogen precipitation activity.The acid etched catalyst has an initial overpotential of～80 m V,an overpotential of 210 m V at a current density of 10 m A/cm²,and a Tafel slope of 97 m V/dec,showing excellent performance compared to the untreated material.Acid treatment can effectively control the defect degree and improve the catalytic activity,which provides a useful reference for the design and preparation of catalyst.（3）Based on the existing research on the defects regulation of Mo S₂and its electro-catalytic properties,we further extended the defect regulation method to multi-component composite materials and applied it to electrochemical glucose sensors.The defective Mo S₂/Ni S₂/r GO composite was synthesized by a simple one-pot hydrothermal method,and the high performance of non-enzymatic glucose detection was realized.It has been proved by various physical and chemical characterization that the composite material has more active sites and excellent charge transfer characteristics due to multiple defects and the synergistic effect among components,and has good electrocatalytic performance for glucose oxidation reaction.The sensor showed a wide linear range（0.001～7.5 m M）,high sensitivity(879.8 A m M^-1 cm^-2),rapid response（≤4 s）and low detection limit（80 n M）for glucose concentration detection.At the same time,it has good selectivity,reproducibility and stability.Therefore,the defective composite is a promising electrocatalyst for nonenzymatic glucose detection.（4）We further extend the above catalyst surface defect design method to the Layered double hydroxides（LDHs）material system and apply it to electrocatalytic oxygen evolution reaction（OER）.The defective Co Fe-LDHs（D-Co Fe-LDHs）was prepared by simply treating with H₂O₂ at room temperature and using hydrogen peroxide to react with metal elements in LDHs.It showed a low overpotential（283 m V）at a current density of 10m A/cm² and a Tafel slope as low as 39 m V/dec.Physical and chemical characterization proved that after H₂O₂ treatment,a large number of disordered defect structures were generated in the Co Fe-LDHs plane.At the same time,it is found that abundant peroxides are also generated on the surface of LDHs,which,as intermediate species in the OER process,can effectively promote the OER electrocatalytic performance of LDHs.This work provides a simple and effective defect construction strategy for LDHs used as OER electrocatalyst.In this paper,the relationship between defects and catalytic properties of materials is studied.Aiming at the preparation of defective catalyst,a series of efficient defect construction methods were proposed to effectively regulate the electronic structure of the material,optimize the surface properties of the material,thus affecting the characteristics of the electrocatalytic reaction interface,optimize the adsorption and desorption process of the reaction intermediates on the electrode surface and further promote the electrocatalytic reaction.