Preparation Of Copper And Cobalt-based Nanocomposites And Their Electrocatalytic Performance For CO₂ Reduction

In recent years,CO₂emissions surged year by year,which has seriously damaged the natural cycle of carbon.Therefore,artificially controlling the balance between carbon emissions and consumption is very important for maintaining and stabilizing the carbon cycle.Among all the pathways for CO₂conversion,electrocatalytic reduction of CO₂,especially in the production of high value-added C₂products,has shown great potential and attracted much attention.The defense process of electrochemical reduction of carbon dioxide is mild,and the conversion of carbon dioxide to the target product can be effectively achieved through the selection of catalysts.The electrochemical reduction method uses electrons and protons as green reaction reagents.The whole process is not only environmentally friendly,but also can be realized at normal temperature and pressure.Metal copper is often used as a catalyst for CO₂reduction,which can electrocatalytically catalyze CO₂to produce C₁products such as CO and formic acid,and C₂products such as ethanol and ethylene.In this paper,a series of copper-based catalysts were prepared to explore the performance of electrocatalytic reduction of CO₂.（1）A three-dimensional porous coral-like nitrogen doped carbon modified Cu（NC-Cu）catalyst with rich Cu-N-C active sites was designed and synthesized by co-precipitation method,and the electrocatalytic CO₂reduction catalyst with high electrocatalytic activity was controllable synthesized by a simple green route.The electrochemical test results showed that under the condition of CO₂-saturated 0.5 M KHCO₃electrolyte,NC-Cu electrode could effectively and controllably convert CO₂into other reduction products,such as CO,HCOOH and C₂H₅OH.At an electrode potential of-0.93V（vs RHE）,the current density can reach 22m A cm^-2and the maximum FE of ethanol can reach more than 30%.The excellent electrochemical CO₂RR performance of NC-Cu catalyst can be attributed to the good design of 3D porous NC-Cu catalyst with rich Cu-N-C active sites.（2）A series of Cu O/r GO composite catalysts were prepared by hydrothermal method,and Cu O was successfully combined with graphene.Through the analysis of electrochemical tests,when the amount of graphene added is 40 mg,the catalytic activity of the catalyst is the best.Under the overpotential of-0.83V,the current density of electrocatalytic CO₂RR was stable at 30m A cm^-2,and the Faraday efficiency of the obtained liquid product ethanol was about 27%.Since the two materials form a synergistic active site,the current density and initial reduction potential of the electrocatalytic CO₂RR of the Cu O/r GO composite are improved compared to the two separate materials of Cu O and graphene.（3）A kind of Cu O/Co₃O₄composite catalysts were prepared by a simple hydrothermal method,and Cu O and Co₃O₄were successfully composited.The catalytic with the molar ratio of Cu O to Co₃O₄is 3:1 shows the best activity.Under the overpotential of-0.93V,the current density of electrocatalytic CO₂RR was stable at 29m A cm^-2,and the Faraday efficiency of the obtained liquid product ethanol was about 25%.Compared with Cu O and Co₃O₄,the current density and initial reduction potential of Cu O/Co₃O₄composites for electrocatalytic CO₂RR were improved,because of the rich active sites formed by the synergistic effect between Cu O and Co₃O₄.