Selective CO Reduction to Ethylene Mediated by Adaptive Small-molecule Engineering of Copper-based Electrocatalysts.

Electrochemical CO reduction reaction (CO RR) over Cu catalysts exhibits enormous potential for efficiently converting CO to ethylene (C H ). However, achieving high C H selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu-based material to a pathway that facilitates CO reduction to C H products. An excellent Faraday efficiency (FE) of 63.6 % on C H with a current density of 497.2 mA cm in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH . The in situ X-ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cu during the CO RR. Furthermore, theoretical calculations demonstrate that the Cu /Cu interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C H production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO reduction to value-added chemicals.