Oxygen-Bridged Dual Catalytic Sites Enable Asymmetric C─C Coupling for Efficient CO2 Electroreduction to Ethanol.

Understanding C─C coupling pathways is essential for achieving selective CO2 conversion into multi-carbon products. However, controlling intermediates dimerization remains highly challenging due to both the complexity of the catalytic systems and the limited mechanistic knowledge into the C─C coupling process. In this work, a model dual-site catalyst with precisely configured Fe-O-Cu sites is designed by covalently grafting iron-phthalocyanine (FePc) onto copper nanowires via oxygen bridges (FeN4-O-Cu NW), which enables probing of atomic-level mechanistic insights into the C─C coupling pathways during electrochemical CO2 reduction reaction (CO2RR). Remarkably, the FeN4-O-Cu NW exhibits a 23.6-fold enhancement in the ethanol-to-ethylene Faradaic efficiency ratio as compared to O-Cu NW, achieving > 80% C2+ Faradaic efficiency at an industrially relevant current density of 1 A cm-2. 13CO2/12CO co-feed experiments together with a collection of operando/in-situ characterizations reveal that the enhanced ethanol selectivity over FeN4-O-Cu NW arises from asymmetric C─C coupling between *CO and *CHO intermediates, where *CO is generated at the low-spin single-Fe-atom site, while *CHO is produced at the oxygen-bridged Cu site. Density functional theory (DFT) calculations further unveil that the oxygen-bridged Fe-O-Cu site can not only stabilize the in situ generated low-spin Fe(II) active site for enhancing CO2 activation and lowering *CO desorption energy but also construct an oxygen-bridged Cu active site to stabilize the *OCHO intermediate, significantly lowering the *OCHO-to-*CHO conversion energy barrier, orchestrating an efficient asymmetric *CO─*CHO coupling path and boosting the CO2-to-ethanol conversion.