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  Hydrophobic edge-rich Zn-doped CuO catalyst developed via a hydrothermal method.
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  Achieved an ethylene Faradaic efficiency of 53.23% ± 2.60% and a partial current density of 31.03 mA cm−2 at −1.4 V in a H-type cell.
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  Maintained an ethylene Faradaic efficiency of 56.93% ± 2.10% at 350 mA cm−2 in a flow cell.
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  Interfacial hydrophobicity and Zn doping facilitate the intermediate adsorption and optimize the interfacial reaction microenvironment.
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  In situ spectroscopy reveals asymmetric *CO-*COH coupling pathway.

The electrochemical reduction of carbon dioxide (CO2) to ethylene (C2H4) represents a promising route for sustainable carbon utilization. However, competitive hydrogen evolution and a low efficiency of carbon‑carbon (CC) coupling limit the selectivity of the electrocatalytic CO2-to-C2H4 conversion. Herein, we developed Zn-doped CuO catalysts (Hydrophobic-CuZnO, abbreviated as HB-CuZnO) featuring an edge-rich microstructure, which possess good interfacial hydrophobicity. In a flow cell, HB-CuZnO exhibited an ethylene selectivity (FEC2H4) of 56.93 ± 2.10% at 350 mA cm−2. In a H-type cell, HB-CuZnO exhibited a high FEC2H4 of 53.23 ± 2.60% and a partial ethylene current density of 31.03 mA cm−2 at −1.4 V vs. RHE, representing an obvious improvement over both pristine CuO (FEC2H4 of 29.11 ± 1.71%) and CuZnO (FEC2H4 of 39.27 ± 1.55%). The in situ ATR-FTIR and Raman spectroscopies further reveal that the cooperative effects of Zn incorporation and iodine-oriented morphological regulation facilitate the intermediate adsorption and optimize the interfacial reaction microenvironment, thus favouring the asymmetric *CO-*COH coupling pathway for enhanced ethylene formation.