Synthesis Of Transition Metal-organic Frameworks And Study Of Anode Oxygen Evolution Preformance

Efficient and clean renewable energy is of great significance to solve the current world energy shortage and environmental pollution.Hydrogen energy has become one of the most promising energy sources in the 21st century clean energy system,the electrolysis of water to produce hydrogen is a simple and fast strategy,which includes two half reactions:anode oxygen evolution reaction（OER）and cathode hydrogen evolution reaction（HER）.However,the OER process involves multiple electron transfer and the formation of O=O double bonds,which leads to a slower kinetic process and a higher overpotential.Therefore,an efficient and stable catalyst must be designed to speed up this process.In recent years,transition metal catalysts have been extensively studied in OER due to their low price,excellent conductivity and high activity.Among them,nickel and iron-based catalysts are the most prominent.The MOF material formed by metal ions or metal clusters and organic ligands has high specific surface area,porosity and structural flexibility,so it has been widely used in adsorption,separation and catalysis.Although MOF materials have shown excellent catalytic performance in OER,it is still very challenging to directly use MOF with poor conductivity and low stability as OER catalysts.Therefore,the main research content of this article is to improve the conductivity to improve the catalytic performance.In this paper,different metals are introduced into MOF to prepare bimetallic MOF,double MOF heterostructure and MOF morphology control as well as surface modification to improve the conductivity of the catalyst,increase the active area and adjust the electronic structure,and ultimately promote the improvement of OER performance.This article mainly uses SEM,TEM,XRD,TG,BET,Raman,FT-IR,XPS,etc.to characterize the structure and properties of the catalyst,and test the performance of the catalyst through the electrochemical workstation.1.Preparation of bimetallic Ni Fe–MOF on the surface of NF by in-situ solvothermal method.The presence of Fe can improve the conductivity and stability of the catalyst,and change the electronic environment of Ni in the catalyst.The synergy effect between Fe and Ni,high conductivity and larger active area are the main reasons for improving catalytic performance.In addition,it has an ultra-low overpotential of160 m V at a current density of 10 m A cm^-2 and long-term stability.2.Solvothermal method is used to prepare catalysts with double MOF heterostructures.ZIF@MIL catalyst is obtained by preparing a layer of uniformly dispersed MIL-100 on the outer surface of ZIF-67,the strong synergistic effect between the two different MOF materials is the key to improving the catalytic performance.Compared with pure ZIF-67 and MIL-100 catalysts,ZIF@MIL has high catalytic performance,excellent conductivity and faster charge transfer ability.In addition,it has a low overpotential of 237 m V and long-term stability at a current density of 10 m A cm^-2.3.Using two-step solvothermal method to anchor Ag NPs on MIL-100/NF with nanosheets to obtain Ag@MIL-100/NF.The prepared catalyst has high conductivity and more active sites,and the addition of Ag NPs can significantly improve the electronic environment of metallic Fe and Ni,which together improve the OER catalytic performance.In addition,compared with pure MIL-100/NF,Ag@MIL-100/NF has a low overpotential of 207 m V and long-term stability at a current density of 50 m A cm^-2.