Balancing *CHO/*CO Intermediate Flux via Carbonyl-Hydroxyl Motif Synergy Enables High-Selectivity Ethanol Electrosynthesis from Dilute CO2.

The electrochemical CO2 reduction reaction (CO2RR) to ethanol represents a sustainable avenue to close the carbon cycle and produce renewable fuels, yet challenges persist in achieving high selectivity and activity under industrially relevant dilute CO2 streams. Herein, we realize an efficient ethanol electrosynthesis by coating Cu catalysts with β-hydroxy ketone-based covalent organic polymers (COPCO+OH), which not only activate CO2 but also balance the *CHO/*CO flux at the catalyst-electrolyte interface. The COPCO+OH coated Cu NPs (Cu+COPCO+OH) exhibits unprecedented FEEtOH of 54.2% in 0.5 M KHCO3, with a partial current density of 121.3 mA cm-2. Crucially, using a dilute CO2 feedstock (20% CO2), it retains ∼40.8% FEEtOH, circumventing energy-intensive CO2 purification. Through systematic experimental characterizations and density functional theory (DFT) calculations, we elucidate a unique organic motif synergy: carbonyl groups serve as CO2 activation centers, while adjacent hydroxyl groups boost *H supply for *CO protonation to *CHO intermediates. This unique synergy enables a balanced *CHO/*CO flux, thereby creating an optimal environment favoring asymmetric *CHO-*CO coupling and preferentially stabilizing the *CHCOH intermediate toward ethanol production. Our investigations establish a universal design paradigm to bypass scaling relations in CO2RR through organic motif synergy, offering atomistic insights into steering complex reaction networks in CO2 electroreduction.