Impact of Adsorbed CO on the Conversion of CO2 to Ethylene on 4,5-Dicyanoimidazole Coordinated Cu

Upgrading carbon dioxide (CO2) into multicarbon products by using renewable electricity provides a pathway to producing fuel and chemicals. In fact, input CO2 in alkaline and neutral reactors forms carbonates with hydroxide, resulting in lower carbon efficiency, so acidic electrolytes are considered as a strategy to solve this problem. However, hydrogen evolution reaction competition and lower Faradaic efficiency (FE) of the target product limit the development of acidic electrolytes. Here, we report an accessible composite catalyst of a commercial copper (Cu) powder modified by a small molecule 4,5-dicyanoimidazole (DCI) that can maintain a high FE for ethylene (C2H4) even in strong acids with pH ≤ 1. We achieve CO2 electroreduction on the DCI–Cu catalyst with an FE of 57% toward C2H4 at a current density of 200 mA cm–2 at pH 1. By in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy measurements, compressed bonding of the *CO intermediate has been observed, which leads to more C–C bonding. The density functional theory calculation results further prove that the adsorbed *CO intermediates on the DCI–Cu catalyst are closer to the reaction sites. Unfortunately, this catalyst still requires improvement in terms of long-term operation. However, we anticipate that this may be generalized to enable molecular strategies to complement metal-based catalysts designed for strong acidic conditions by stabilizing intermediates.