Performance Research Of Non-noble Metal Catalysts For Electrocatalytic CO₂ Reduction In Ionic Liquid Eletroyte System

Technological development promotes the progress of human civilization,but the inevitable massive use of fossil fuels also leads to excessive emissions of carbon dioxide（CO₂）.As the concentration of CO₂ in the atmosphere continues to increase,it breaks the carbon and oxygen balance in the atmosphere maintained by plant photosynthesis,causing environmental problems such as the greenhouse effect.Considering that CO₂ is a renewable C₁ resource,the development of CO₂ conversion technologies to reduce it to fuel or value-added chemicals is necessary to achieve the goal of"carbon neutrality"by 2060.Compared to other CO₂ conversion methods,electrocatalytic CO₂ reduction（ECR）is one of the most attractive solutions,due to its mild operating conditions,controlled target product,clean energy compatibility,and technical feasibility in real industrial applications.Despite the current progress in this field,several key challenges still exist.First,since the ECR reaction usually carried out in aqueous solution,it is inevitably accompanied by a competitive process of hydrogen evolution reaction（HER）.In addition,ECR is a reaction process involving multi-electron and multi-proton coupling,which can yield a wide range of carbon-based products with low selectivity.Moreover,the high cost and structural instability of conventional catalysts further limit the large-scale application of ECR.Therefore,this paper mainly focuses on non-precious metal catalysts and optimizes the selectivity of target products by appropriate regulation strategies to improve the overall performance of ECR in ionic liquid electrolyte system.Specific research contents are as follows:（1）To address the ECR inertness of the main group metal oxide MgO in the s region,the ECR performance of 2D MgO nanosheets was improved by controlling the calcination atmosphere and time to construct different oxygen vacancy（V_O）concentrations.In an ionic liquid electrolyte（0.5 M[Bmim]PF₆/MeCN）,two-dimensional MgO nanosheets with abundant V_O（V_O-rich MgO）exhibited optimal ECR performance.The Faraday efficiency of CO was as high as 99.6%at an applied potential of-2.2 V vs.Ag/Ag⁺with a generation rate of up to 890.11μmol mg^-1 h^-1.Electrochemical experiments and characterization tests demonstrate that the high specific surface area,abundant V_O and exposed Mg sites of the 2D V_O-rich MgO nanosheets facilitate the adsorption of CO₂ and desorption of CO;Density functional theory calculations show that the introduction of V_O into MgO significantly reduces the reaction energy barrier for the conversion of*COOH to*CO（electrocatalytic CO₂ to CO decisive step）,thus greatly facilitating the catalytic conversion of CO₂.（2）To address the problems of poor conductivity and poor ECR selectivity of the metallic sulfide CdS,diethylenetriamine（DETA）was introduced into the CdS surface via a surface modification strategy to obtain amino-functionalized organic-inorganic hybrid CdS-NH₂ nanobelts,which significantly enhanced the current density and CO Faraday efficiency of ECR.In the wide electrochemical window of-1.9～-2.4 V vs.Ag/Ag⁺,the CO Faraday efficiency of CdS-NH₂ is higher than 90%,and the CO partial current density can reach-134.8 m A cm^-2only in the H-type electrolytic cell.Compared with the unmodified pure CdS material,the introduction of amino group stabilized the*COOH intermediate and significantly improved the selectivity of CO products.In addition,by using water as an additive to form a ternary electrolyte solution with 0.5M[Bmim]PF₆/MeCN,and selecting different organic media as solvents,the effects of water and organic media on the electrocatalytic performance of CO₂were investigated,which provided a new reference for selecting the best electrode-electrolyte system.