Asymmetric C─C Coupling Induced by a Potential Field Boosts Electrocatalytic CO ₂ Reduction to Multi‐Carbon Products

The complex reaction interface and the high reaction barrier for C─C coupling hinder the conversion of CO 2 toward high‐value C 2+ products. In this work, thiol is employed to modify facet‐controlled Cu nanoparticles, systematically elucidating the tripartite interaction between organic modifiers, active sites, and key intermediates. Theoretical calculations, Kelvin Probe Force Microscope (KPFM), and in situ investigations reveal that the thiol‐derived spatial potential field facilitates CO 2 activation and the formation of hydrocarbon intermediates ( * COH). More importantly, the results demonstrate that the C 2+ products of the thiol‐modified catalyst are strongly dependent on the crystal planes: the potential field preferentially drives suitable adsorbed * COH to asymmetric * CO‐ * COH coupling on Cu (100)/(111) interface. Consequently, the C 2+ selectivity of the thiol‐modified Cu (100)/(111) interface‐rich Cu nanoparticle is intrinsically enhanced, exhibiting high selectivity to C 2+ products with a faradaic efficiency (FE) of 85.44%. Remarkably, the structure achieves a C 2 H 4 FE of 73.79% ± 2.69% with a peak partial current density of 345.75 mA cm − 2 (total current: 1.38 A). Beyond establishing a high‐efficiency CO 2 to C 2+ conversion protocol, this study provides mechanistic insights into the selective steering of C─C coupling through tailored surface modifications.