Design And Synthesis Of A Metal-based Catalysts And Their Applications In Electrochemical Reduction Of Carbon Dioxide

Carbon dioxide(CO₂)is the major greenhouse gas,it is also an important renewable C₁ resource.Chemical utilization of CO₂ is of dual significance for environmental protection and rational utilization of carbon resources.The conversion and utilization of CO₂ has attracted much attention worldwide.CO₂ is a dynamically inert and thermodynamically stable molecule,and its chemical transformation and utilization process often requires harsh reaction conditions.Therefore,it is very important to find a low-cost,clean and efficient transformation method to realize the"carbon cycle".Electrocatalytic CO₂ conversion can use clean electric energy under mild conditions.It can not only convert CO₂ into high value-added chemicals and fuels,but also effectively utilize renewable electric energy,which is one of the most promising CO₂ resource utilization routes.In recent years,the field of electrocatalytic CO₂ conversion has made continuous progress,but it still faces the problems of poor product selectivity and low reaction efficiency,which seriously restrict the industrial application of this technology.Therefore,it is very important to design and prepare cheap and efficient electrocatalysts.Although many different types of catalysts have been reported,the design of catalysts with high activity,selectivity and stability is still an important topic.This paper starts with the design of catalysts,and designs and modifies metal base catalyst.By adjusting the electronic structure of the catalysts and increasing the number of active sites on the catalyst surface,some metal-based electrocatalysts with high catalytic activity were constructed.The main research contents and innovations of this paper are as follows:(1)Ni_xAu_y bimetallic catalysts with different Ni/Au ratios were prepared by one-step aqueous phase reduction method to solve the problems of high cost and low catalytic activity of precious metals.It was found that Ni_xAu_y catalyst has a three-dimensional porous network structure and a lattice disorder defect structure.These characteristics enable it to provide more active sites in electrocatalytic reactions,reduce the charge transfer resistance,and improve the catalytic activity and product selectivity.With Ni₅₅Au₄₅ as electrocatalyst and 0.5 M[Bmim]PF₆/acetonitrile as electrolyte,the CO faraday efficiency(FE)reached up to 92.9%with a current density of 18.7 m A cm^-2.(2)Through defect engineering strategy,oxygen vacancy defects were introduced into Bi₂WO₆ catalyst to obtain Bi₂WO₆ rich in oxygen defects.Electrochemical experiments showed that the catalyst could catalyze the conversion of CO₂ to CO in 0.5M[Bmim]PF₆/Me CN electrolyte,with a FE of 91.0%and a current density of 43.2 m A cm^-2.Further studies showed that the introduction of oxygen vacancy could effectively regulate the electronic structure of Bi₂WO₆ catalyst surface,enhance the effect of electron enrichment,and activate CO₂ molecules.At the same time,the introduction of oxygen vacancy could promote electron transfer at the electrode interface and provide more catalytic active sites for the catalytic reaction.(3)A Cu O/Ce O₂ catalyst was prepared by supporting Cu O on efect-rich Ce O₂nanorods as support by precipitation method,in which the Cu O and the support had strong interaction.It was shown that the catalyst had strong CO₂ adsorption capacity,could provide more active sites for catalytic reaction,and had low interfacial charge transfer resistance.In the electrochemical reaction,the catalyst showed good selectivity for C₂H₄and stability,and the FE of C₂H₄ reached 50.5%,and the current density was18.0 m A cm^-2.(4)A Cu-based electrocatalyst with abundant metal vacancy(Cu-0.5/CP)supported on carbon paper(CP)was prepared by in-situ electrodeposition using nitrotriacetic acid(NTA)as additive.The catalyst was used in electrocatalytic CO₂,and the FE of C₂₊products reached 61.6%,and the current density was 12.3 m A cm^-2.The faraday efficiency of C₂H₄ reached 44.0%.In addition,the electrodeposition method could also be extended to the synthesis of Pd and Zn metal electrodes,and could be used as electrocatalyst for transformation of CO₂to CO,indicating that NTA has a certain universality in electrodeposition preparation of electrocatalysts.