Reconstruction‐Derived Surface Hydroxyl Enrichment Steers Selective CO‐to‐Acetate Electroconversion via Adsorbate Synergy

The selectivity of electrochemical CO reduction (CORR) on Cu‐based catalysts is critically governed by dynamic surface reconstruction and the resulting interfacial adsorbates. However, how reconstruction‐derived surface species cooperatively dictate the acetate pathway remains poorly understood. Here, we employ a Cu 2 O/Cu heterostructure as a precursor model catalyst that generate a surface enriched in adsorbed OH species (OH ad ) upon its reconstruction into metallic Cu. Operando spectroscopy characterizations clearly reveal that surface‐enriched OH ad synergistically strengthens the adsorption and activation of active low‐frequency‐band *CO intermediates and steers C─C coupling toward acetate over ethanol/ethylene through OH ad ‐CO ad synergistic interaction, as further corroborated by our first‐principles density functional theory (DFT) calculations. The reconstructed catalyst achieves an acetate Faradaic efficiency of ∼73.7% (79.5% of all C 2+ product), delivers a peak partial current density of 298.9 mA cm −2 , and maintains stable catalytic operation over 120 h of continuous electrolysis. This work establishes a fundamental operando mechanistic framework linking reconstruction‐derived OH ad enrichment to selective CO‐to‐acetate electroconversion, and provides guiding principles for rational interfacial engineering of Cu‐based catalysts toward targeted C 2+ product selectivity in renewable electricity‐driven CORR.