Study On Electrocatalytic Reduction Of Carbon Dioxide With Copper-based Catalysts

The massive combustion of fossil fuels leads to excessive CO₂emissions into the atmosphere,causing serious environmental problems,and the development of CO₂ resource utilization technologies is urgent.Among the many means of CO₂ resource recovery,electrocatalytic reduction of CO₂（ECR）is gaining more and more attention because of its advantages of combining clean energy（such as solar,wind,tidal energy,etc.）,mild reaction conditions and efficient conversion into high value-added products.CO₂ electroreduction products are diverse,such as C₁ products including CO,HCOOH,CH₄ and C₂₊products including C₂H₄,C₂H₅OH,n-C₃H₇OH,among which C₂₊products have received more attention because of their higher energy intensity and economic potential.Cu-based catalysts are known as efficient catalysts for the electrocatalytic production of C₂₊products from CO₂.Our works mainly design copper-based catalysts to improve the performance of ECR for C₂₊products production.The specific research contents are as follows:（1）Currently,tandem catalysis has emerged as a promising strategyto promote the production of C₂₊products from ECR.In this work,Cd（OH）₂@Cu O composites were synthesized by a simple hydrothermal method.The successful synthesis of Cd（OH）₂@Cu O composites was demonstrated by various characterizations such as TEM and XPS.The total Faraday efficiency（FE）of C₂₊products（C₂H₄,C₂H₅OH,n-C₃H₇OH）in 0.1 M KHCO₃ electrolyte at-1.05 V vs.RHE was as high as 52.9%,with 29.9%FE for C₂H₅OH.TEM showed that the introduction of Cd（OH）₂ caused an increasing content of defects in Cu O surface at the Cd（OH）₂-Cu O interface,which was beneficial to enhance the adsorption of CO intermediates and thus promote the formation of C₂₊products.DFT calculation shows that Cd（OH）₂ is beneficial to the formation of CO,forming a CO rich region at the interface of composite materials,and promoting the C-C coupling to produce C₂₊products through the tandem catalytic mechanism coupled with copper oxide.The introduction of Cd（OH）₂can promote the water decomposition to increase the coverage of active hydrogen on the catalyst surface to assist the formation of ethanol products.（2）4%Sb₂O₃@Cu₂O catalyst was prepared by a simple one-potsynthesis method.The successful synthesis of Sb₂O₃@Cu₂O catalyst was demonstrated by XPS,Raman and other characterizations.In an H-type cell,the total FE of C₂₊products（C₂H₄,C₂H₅OH,n-C₃H₇OH）over 4%Sb₂O₃@Cu₂O at-1.1 V vs.RHE in 0.1 M KHCO₃ electrolyte was as high as 57.8%,accounting for 80%of the total ECR products,with C₂H₄ selectivity as high as 40.0%,which was about 70%of the total C₂₊products.An ethylene selectivity of 61.0%was achieved in a flow cell with a current density of-600 m A cm^-2,which reached the electrolytic density of commercial electrolysis.According to the analysis of CO electroreduction（CORR）experimental results,4%Sb₂O₃@Cu₂O is more conducive to the adsorption and activation of CO than pure Cu₂O,thus promoting the dimerization of*CO to produce C₂H₄ products.