Preparation Of ZIF-67-derived Bimetallic Oxide Catalyst And Study On Its Oxygen Reduction/precipitation Performance

To achieve sustainable economic growth and reduce environmental pollution,countries should adhere to the concept of green economy and actively develop clean new energy.We learned that oxygen reduction and oxygen precipitation reactions（ORR/OER）play a vital role in energy conversion devices.In this study,a bimetallic composite with a stable core@shell structure based on MOFs derivatives was constructed to improve ORR/OER performance.This article were prepared two（Co₃O₄@Z67-NT@CeO₂ and CoO@GC/WO₃@CL）dual-function electrocatalysts,both of which are based on MOFs（ZIF-67）derived bimetal oxide multilayer structures,and passed a large number of Materials physical characterization methods and electrochemical（ORR/OER）performance testing methods analyze their material composition,element valence,pore size,apparent morphology,starting potential,current density and stability,etc.Mechanism makes reasonable inferences.A porous metal-doped nitrogen-carbon framework Co₃O₄@Z67-NT was prepared using ZIF-67 polyhedron as a precursor to a carbonization temperature of 500-900℃.Then,through a simple hydrothermal process,CeO₂ nanoparticles were uniformly coated on the surface of the porous Co₃O₄@Z67-NT substrate.The obtained Co₃O₄@Z67-NT@CeO₂ composite material basically retains the original morphology of the ZIF-67polyhedron and exhibits excellent bifunctional（ORR/OER）catalytic activity.ORR))is0.70 V.For ORR,the half-wave potential of Co₃O₄@Z67-N700@CeO₂ is 0.88 V（vs.RHE）,which is attributed to the synergy between CeO₂(Ce³⁺)and Co₃O₄(Co²⁺).The rich oxygen vacancies in CeO₂ can enhance theO₂ on the adsorption interface,thereby promoting the activation of the adsorbedO₂ toO₂-,which alleviates the lack ofO₂during the ORR,thereby increasing the ORR activity.For OER,Lower overpotential（350 m V）of Co₃O₄@Z67-N700@CeO₂ at 10 m A cm^-2,the Faraday efficiency is 92.2%.The effective valence state transition between Ce³⁺and Ce⁴⁺gives CeO₂ high conductivity and oxygen storage capacity,which greatly promotes Charge transfer and the generation and smooth transportation of highly active substances(O₂^2-/O^-).In this study,the interaction between CeO₂(Ce³⁺/Ce⁴⁺and oxygen vacancies)and Co₃O₄(Co³⁺/CoOOH)provided more electrochemically active sites for the ORR/OER process.In addition,in the presence of polyvinylpyrrolidone,WO₃ microrods were evenly distributed on the surface of ZIF-67 dodecahedron.ZIF-67/WO₃-MRs precursors are carbonized at different temperatures（600-1000℃）.WO₃ spheres（at 800℃）wrapped from a thin layer of carbon derived from WO₃ microrods are anchored in situ at ZIF-67-derived CoO Graphitized carbon on the surface to obtain CoO@GC/WO₃@CL catalyst.The catalyst basically retains the dodecahedron structure,high specific surface area and porous structure of ZIF-67.For ORR,CoO@GC/WO₃@CL-800 has a corrected peak potential（0.81 V vs.RHE）.The synergy between WO₃（oxygen vacancy）and Co²⁺improves the mass/charge transfer efficiency,thereby enhancing the 4e^-ORR pathway.PVP-derived CL can stably embed highly active Co²⁺in the GC structure,thereby improving ORR stability.For OER,at 10 m A cm^-2,the overpotential of CoO@GC/WO₃@CL-800 is low（330 m V）and the Faraday efficiency is 91.8%higher.The strong interaction between CoOOH(Co³⁺)and oxygen vacancies（WO₃）can promote H₂O oxidation and further promote the production ofO₂.CoO@GC/WO₃@CL-800 has aΔE of 0.72 V,confirming its promising ORR/OER activity.In this paper,the use of MOF as a template to prepare bimetallic oxide multilayer composite materials has good dual-function（ORR/OER）catalytic activity,indicating the potential application of such catalysts in the field of electrocatalysis.