Electrochemical C-C coupling between CO2 and formaldehyde into ethanol

Electrochemical reaction of CO2 with organic substances can significantly broaden the scope of CO2 utilization and chemical synthesis. However, this is more challenging because it involves simultaneous activation of CO2 and organic molecules, as well as their coupling. Herein, we report the first work to realize ethanol generation from the co-electrolysis of CO2 and formaldehyde. It was discovered that iodine-modified Cu catalyst was efficient for the reaction, and the Faradaic efficiency of ethanol could reach 32.4% with a corresponding formation rate of 1.6 mmol g−1 h−1. Moreover, the reaction mechanism was investigated through in situ experiments and density functional theory calculations. The results indicated that the iodine-modified Cu catalyst was beneficial for CO2 activation and intermediates (i.e., ∗CO, ∗CHO) adsorption, as well as C-C coupling, leading to high selectivity toward ethanol. This work expands the scope of reaction routes for CO2 reduction.