Trace Ionic Liquid-Assisted Orientational Growth of Cu2O (110) Facets Promote CO2 Electroreduction to C2 Products.

Cu2O has great advantages for CO2 electroreduction to C2 products, of which the activity and selectivity are closely related to its crystal facets. In this work, density functional theory calculation indicated that the (110) facets of Cu2O had a lower energy barrier for the C-C coupling compared to the (100) and (111) facets. Therefore, Cu2O(110) facets were successfully synthesized with the assistance of trace ionic liquid ([Bmim]BF4) by a sample wet-chemical method. A high faradaic efficiency of 71.1% and a large current density of 265.1 mA cm-2 toward C2H4 and C2H5OH were achieved at -1.1 V (vs. reversible hydrogen electrode) in a flow cell. The in-situ and electrochemical analysis indicated that it possessed the synergy effects of strong adsorption of *CO2 and *CO, large active area and excellent conductivity. This study provided a new way to enhance the C2 selectivity of CO2 electroreduction on Cu2O by crystal structure engineering.