Differential Chloride Affinity Over Amorphous-Crystalline Interfaces Drives Asymmetric C─C Coupling for Neutral CO₂ Electroreduction to Ethanol

Electrocatalytic CO₂ reduction to ethanol in neutral electrolytes represents a promising pathway for carbon neutrality, yet the selectivity remains unsatisfactory due to inefficient C─C coupling and competitive hydrocarbon production. Herein, a copper oxide catalyst with enriched amorphous-crystalline interfaces (IR-CuO_x) exhibits differential Cl⁻ affinity, effectively steering the CO₂ reduction pathway toward ethanol. The obtained IR-CuO_x catalyst achieves a remarkable ethanol Faradaic efficiency (FE) of 56.77% at −1.1 V vs. reversible hydrogen electrode (RHE) in 0.1 m KCl electrolyte. Impressively, with IR-CuO_x as the cathode, the integrated membrane electrode assembly (MEA) electrolyzer could stably operate for over 70 h under an industrial-level current density of 200 mA·cm⁻², with ethanol FE remaining above 45%. Experimental characterizations and theoretical calculations demonstrate that the differential Cl⁻ affinity over amorphous-crystalline interfaces synergistically combines the ^*CO hydrogenation capability at weak Cl⁻ affinity sites with the enhanced C─C coupling capability at strong Cl⁻ affinity sites, favoring asymmetric ^*CO-^*CHO coupling to generate the key ^*CHCOH intermediate. Additionally, the differential Cl⁻ affinity further strengthens the C─O bond and weakens the Cu─C interaction, facilitating the hydrogenation of ^*CHCOH toward ethanol. This work offers fundamental understandings of surface anion adsorption behaviors for designing efficient electrocatalysts toward neutral CO₂−to-ethanol conversion.