CO₂ Electrocatalvtic Reduction On Copper/Nitrogen-Doped Carbon Composites

With the development of industrialization,the concentration of CO2 in the atmosphere has been rising year by year,causing a series of serious environmental problems.The electrocatalytic reduction of CO2 has received extensive attention due to its mild reaction conditions.Electrocatalytic reduction of CO2 into economically valuable chemicals and fuels can effectively solve the problem of excessive CO2 concentration in the atmosphere,thereby achieving carbon neutrality.Cu-based metal catalysts can effectively electrocatalytically reduce CO2 to generate various types of hydrocarbons and alcohol products.However,unmodified Cu-based catalysts generally suffer from low current density,poor selectivity and poor stability.Therefore,in the research process of the electrocatalytic reduction of CO2,researchers are devoted to the study of catalysts with high activity,good stability and good selectivity.N-doped carbon materials(NCs)are commonly used in CO2 electrocatalytic reduction due to their large surface area and good electrical conductivity.Based on the above analysis,the main work of this paper is to composite Cu-based catalysts with N-doped carbon materials and apply them to the electrocatalytic reduction of CO2.The specific work is as follows:(1)Cu2O/NC for the electrocatalytic reduction of CO2Cu2O was prepared by a simple chemical reduction and applied to the electrocatalytic reduction of CO2.It was found that Cu2O was only stable for 1500 s during the reaction.In order to stabilize and improve the CO2 electrocatalytic performance of Cu+,Cu2O and NC materials form a composite materials for CO2 electrocatalytic reduction process by taking advantage of the weak interaction between N and Cu+.By comparing the XPS data of Cu2O and Cu2O/NC materials,it is found that there is an interaction between Cu2O and NC materials,which can effectively promote the CO2 electrocatalytic reduction reaction.The i-t curve after electrolysis also fully proves this point of view.(2)Application of Cu@NC materials in CO2 electrocatalytic reductionAccording to literature reports,in the catalytic process of CO2 electroreduction to prepare hydrocarbons,both Cu+and Cu0 have catalytic activity.And a higher proportion of pyridine N is beneficial to the adsorption of CO2.Therefore,the catalytic performance of Cu0 is studied in this chapter.Therefore,Cu@NC materials were prepared by high-temperature calcination and applied to the electrocatalytic reduction of CO2.Through the analysis of the electrolysis results of Cu@NC-3,NC and Cu-N-C materials,it is found that Cu nanoparticles are beneficial to the formation of C1 under certain experimental conditions.Under the potential condition of-1.65 V vs.RHE,the Faradaic efficiency of the C1 product for CO2 electrocatalytic reduction of Cu@NC-3 material is 53%,and the Faradaic efficiency of CH4 can reach 30%.Through the study of a series of Cu@NC materials,it is found that the Cu@NC-3 material has the highest proportion of pyridine N,which is more conducive to the adsorption of CO2 and promotes the electrocatalytic reduction of CO2.Long-term electrolysis of Cu@NC-3 shows that the material can be stable for 3 h.