Studies On Electrochemical Reduction Of Carbon Dioxide To Multicarbon Products Over Cu-based Catalytic Materials

At present,the global energy structure is still dominated by fossil energy,and non-fossil energy is also growing steadily.The CO₂generated by fossil energy has caused a series of energy and environmental problems.At the same time,the difficulty of storing excess electric energy has also become an urgent problem to be solved.Electrocatalytic carbon dioxide reduction reaction（CO₂RR）can convert CO₂ into value-added fuels and chemicals.The products can also be used as energy carrier molecules to store electrical energy.The artificial closure of the carbon cycle can not only alleviate the"greenhouse effect",but also contribute to the achievement of the"two-carbon"goal.The study of copper-based catalysts for the production of multi-carbon products(C₂₊)from CO₂RR is a topic with great research potential and challenges.Copper is one of the few metal that can efficiently electroreduce CO₂ to multi-carbon olefins or alcohols.However,its reduction products are extremely complex and the side reaction of hydrogen evolution is serious.Therefore,the C₂₊Faradaic efficiency and the activity is low and the stability of catalysts is poor.Finding and studying the real catalytic active sites and generation mechanism of C₂₊is particularly important for this research direction,which is also the key to controlling its selectivity.To improve the selectivity of C₂₊,the chemical behavior of CO^（9）needs to be regulated so that it develops in the direction of^（9）C₂.The nanostructure,electronic structure and chemical environmental of Cu are closely related to the adsorption activation and transformation activation energy of key intermediates.The research in this paper is as follows:（1）Pre-catalysts of copper catalysts were synthesized by precipitation method.First,the copper produced by electrochemical reconfiguration of different precursors during the synthesis process was studied for CO₂RR.Cu O-derived copper（OD-Cu）achieved high C₂₊selectivity（78%）and partial current density(663 m A cm^-2)because of its large specific surface area and complex grain boundaries network of（111）/（100）.The synergistic effect of crystal facets on C₂₊selectivity was investigated by adjusting the facets ratio of Cu（111）to Cu（100）.The facet effect of O-D Cu crystal promote the selectivity of C₂₊owing to the high coverage with different configurations,subsequent hydrogenation and C-C coupling reaction process of^（9）CO.（2）A gold-copper composite material was prepared by thermal reduction and high-temperature hydrogen reduction strategy.The Au particles with a size of about 10nm were supported on the copper carrier.Au provides Cu with a surface^（9）CO-rich chemical environment,which improves the efficiency of Cu for C-C coupling.Compared with pure copper material,the Au/Cu-H300 composite exhibited better CO₂RR performance and significantly improved the Faradaic efficiency of n-propanol（n-Pr OH）.Au and Cu synergistically promote the produce of^（9）C₂and coupling of^（9）C₂and^（9）C₁.By adjusting the loading of Au,it is found that the Faradaic efficiency of n-Pr OH can reach 14%,which is more than 4 times that of pure copper.The tandem catalyst designed in this chapter provides an idea for preparing copper-based catalysts with high C3 product selectivity.