A Conductive Dinuclear Cuprous Complex Mimicking the Active Edge Site of the Copper(100)/(111) Plane for Selective Electroreduction of CO2 to C2H4 at Industrial Current Density

Abstract

Inorganic solids are a kind of important catalysts, and their activities usually come from sparse active sites, which are structurally different from inactive bulk. Therefore, the rational optimization of activity depends on studying these active sites. Copper is a widely used catalyst and is expected to be a promising catalyst for the electroreduction of CO2 to C2H4. Here, we report a conductive dinuclear cuprous complex with a short Cu···Cu contact for the electroreduction of CO2 to C2H4. By using 1H-[1,10]phenanthrolin-2-one and Cu(I) ions, a dinuclear cuprous complex [Cu2(ophen)2] (Cuophen) with a remarkable conductivity (3.9 × 10−4 S m−1) and a short intramolecular Cu···Cu contact (2.62 Å) was obtained. Such a short Cu···Cu contact is close to the distance of 2.54 Å between 2 adjacent Cu atoms in the edge of the copper(100)/(111) plane. Detailed examination of Cuophen revealed a high activity for the electroreduction of CO2 to C2H4 with a Faradaic efficiency of 55(1)% and a current density of 580 mA cm−2, and no obvious degradation was observed over 50 h of continuous operation. Comparing the properties and mechanisms of Cuophen and 2 other copper complexes with different Cu···Cu distances, we found that the shorter Cu···Cu distance is conducive not only for a *CO species to bridge 2 copper ions into a more stable intermediate transition state but also for C–C coupling.