Preparation And Oxygen Evolution Performance Of CeO₂ Modified MOF-based Electrocatalyst

With the increasing global energy demand,hydrogen,as a clean energy source,has been widely concerned.At present,hydrogen production by electrolysis of water is a clean energy technology with great prospect and potential.Electrochemical decomposition of water has two and a half reactions.Compared with HER,the kinetic process of OER is very slow,which requires higher energy or higher overpotential to overcome the reaction energy barrier.It can be said that OER is the main factor that restricts the industrialization development of hydrogen production technology by electrolysis of water.Researchers are constantly developing anode materials,such as precious metals and metal oxides,to optimize the whole electrolysis process.Precious metal oxides are good electrocatalysts,but their highcost limits their wide application.Therefore,it is of great significance to prepare efficient,stable and cheap OER electrocatalyst.In this paper,MOF-based electrocatalysts were designed and modified by different treatment methods to adjust and optimize their electrocatalytic performance.The electrocatalysts were evaluated and analyzed by XRD,SEM/EDS,FT-IR,Raman,BET,UV-Vis,TG and electrochemistry.The specific work is as follows:1.Ce_1-xCu_xO new electrocatalyst was prepared by pyrolysis in air using Ce-MOF as precursor template and introducing the second metal copper.The effects of pyrolysis temperature and metal proportion on the physical and chemical properties of electrocatalyst were studied in detail,and the OER process mechanism of electrocatalyst was explored through a series of characterization results.The results show that the rod-shaped bimetallic composite catalyst prepared by doping CeO₂semiconductor material with copper keeps the original crystal structure.Cerium oxide nanorods are highly reducible and active carriers of copper oxide catalysts,and the interaction between copper species and cerium oxide is strong,and the surface defects of nanorods are abundant,which further improves the catalytic performance of semiconductor electrocatalyst.η₁₀ in 1 M KOH is 351 m V,the slope of Tafel is 82.6m V·dec^-1,and the catalytic stability can be maintained for 20 h.2.CeO₂ semiconductor was prepared by hydrothermal method,calcination method and template method,and three kinds of CeO₂/Cu-MOF binary composite electrocatalysts were prepared by hydrothermal method.XRD,SEM/EDS,FT-IR,Raman,BET,UV-Vis and TG were used to characterize the structure,and the electrochemical OER catalytic performance was tested by PARSTAT electrochemical workstation.The OER process mechanism of electrocatalyst was explored through a series of characterization results.The electrocatalyst prepared by compounding MOFs material with lanthanide metal semiconductor CeO₂ can alleviate the agglomeration problem of CeO₂ semiconductor,promote electron transfer and generate energy to combine oxygen,thus improving the OER performance of the catalyst.It has excellent OER catalytic activity in 1M KOH,withη₁₀ of 348 m V,Tafel slope of 80.9 m V·dec^-1and Faraday efficiency close to 99%.The addition of MOFs material increases the specific surface area of CeO₂,and CeO₂ can coordinate with two strong electronegative ligands based on oxygen and nitrogen functional groups,so that it has good stability in alkaline conditions.3.CeO₂/Cu-MOF/GO ternary composite electrocatalysts were prepared by hydrothermal method in order to improve the stability of electrocatalysts.From the point of view of chemical structure and morphology,the successful synthesis of CeO2/Cu-MOF/GO was demonstrated by FTIR and Raman,and the thermal stability,conductivity and specific surface area of the materials were analyzed by TG,UV-Vis and BET,respectively.SEM and XRD were used to analyze the results.In addition,PARSTAT electrochemical workstation was used to test the catalytic performance of electrochemical OER.The results show that the optimized CeO₂/Cu-MOF/GO catalyst has a low overpotential of 340 m V and a Tafel slope of 77.2 m V·dec^-1 at 10 m A·cm^-2,and has a good stability in alkaline conditions,and its Faraday efficiency is close to100%.