Low-coordinated copper facilitates the *CH₂CO affinity at enhanced rectifying interface of Cu/Cu₂O for efficient...

The carbon-carbon coupling at the Cu/Cu₂O Schottky interface has been widely recognized as a promising approach for electrocatalytic CO₂ conversion into value-added alcohols. However, the limited selectivity of C₂₊ alcohols persists due to the insufficient control over rectifying interface characteristics required for precise bonding of oxyhydrocarbons. Herein, we present an investigation into the manipulation of the coordination environment of Cu sites through an in-situ electrochemical reconstruction strategy, which indicates that the construction of low-coordinated Cu sites at the Cu/Cu₂O interface facilitates the enhanced rectifying interfaces, and induces asymmetric electronic perturbation and faster electron exchange, thereby boosting C-C coupling and bonding oxyhydrocarbons towards the nucleophilic reaction process of *H₂CCO-CO. Impressively, the low-coordinated Cu sites at the Cu/Cu₂O interface exhibit superior faradic efficiency of 64.15  ±  1.92% and energy efficiency of ~39.32% for C₂₊ alcohols production, while maintaining stability for over 50 h (faradic efficiency >50%, total current density = 200 mA cm^-2) in a flow-cell electrolyzer. Theoretical calculations, operando synchrotron radiation Fourier transform infrared spectroscopy, and Raman experiments decipher that the low-coordinated Cu sites at the Cu/Cu₂O interface can enhance the coverage of *CO and adsorption of *CH₂CO and CH₂CHO, facilitating the formation of C₂₊ alcohols.