<i>Operando</i> Strain Modulation Amplifies Asymmetric C─C Coupling for CO‐to‐Acetate Transformation

ABSTRACT Electrochemical carbon monoxide reduction reaction (CORR) powered by sustainable electric energy emerges as a brilliant method to produce valued chemicals, such as acetate. Nevertheless, the performance of current CORR systems remains inadequate for industrial applications, primarily limited by unsatisfactory selectivity and low current density, which are largely governed by the design of electrocatalysts. In this work, we developed an operando strain engineering strategy to regulate the structure of Cu 2 O by introducing smaller Al δ+ into its lattice. During the CORR, the Cu 2 O was reduced to metallic Cu, while the majority of the introduced Al δ+ could simultaneously be removed, which generated a tensile strain. The Al (0.5)/Cu 2 O showed a high partial current density of 198 mA cm −2 and an excellent Faradaic efficiency (FE) of around 60% toward acetate production in a flow cell. In situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) confirmed more pronounced bridge‐bound * CO as well as stronger * CHO and * COCHO over Al (0.5)/Cu 2 O than the Cu 2 O during the CORR. Density functional theory (DFT) calculations clarified that the tensile strain induced by Al δ+ removal during CORR could tune the structure of Cu, strengthen * CO and * CHO adsorption, and facilitate asymmetric * CO─ * CHO coupling to effectively boost CORR to form acetate.