Asymmetrically Coordinated Cu Dual-Atom-Sites Enables Selective CO2 Electroreduction to Ethanol.

Electrochemical reduction of CO₂ (CO₂RR) to value-added liquid fuels is a highly attractive solution for carbon-neutral recycling, especially for C₂₊ products. However, the selectivity control to preferable products is a great challenge due to the complex multi-electron proton transfer process. In this work, a series of Cu atomic dispersed catalysts are synthesized by regulating the coordination structures to optimize the CO₂RR selectivity. Cu₂-SNC catalyst with a uniquely asymmetrical coordinated CuN₂-CuNS site shows high ethanol selective with the FE of 62.6% at -0.8 V versus RHE and 60.2% at 0.9 V versus RHE in H-Cell and Flow-Cell test, respectively. Besides, the nest-like structure of Cu₂-SNC is beneficial to the mass transfer process and the selection of catalytic products. In situ experiments and theory calculations reveal the reaction mechanisms of such high selectivity of ethanol. The S atoms weaken the bonding ability of the adjacent Cu to the carbon atom, which accelerates the selection from *CHCOH to generate *CHCHOH, resulting in the high selectivity of ethanol. This work indicates a promising strategy in the rational design of asymmetrically coordinated single, dual, or tri-atom catalysts and provides a candidate material for CO₂RR to produce ethanol.