Molecular Bridge Enables Dual-Intermediate Synergy for Selective CO₂ Electroreduction to Multicarbon Products

CO₂ electroreduction to multicarbon products offers a sustainable pathway for chemical synthesis, yet its practical efficiency has long been hindered by the kinetically mismatched *CO and *H intermediates, a fundamental bottleneck in multicarbon formation. Here, we address this challenge through a new molecular-bridge-enabled dual-intermediate synergy strategy. By integrating sulfonated cobalt phthalocyanine molecules with two-dimensional Cu nanosheets, we construct a cooperative catalytic interface in which the molecular bridge not only activates CO₂ to generate *CO but also reorganizes the interfacial water network to facilitate proton transfer for *H feeding. This synchronized CO*─H* delivery to the Cu active sites dramatically enhances C─C coupling and subsequent hydrogenation. As a result, the Cu─CS nanosheets achieve 81% Faradaic efficiency for C₂₊ products at 400 mA cm^-2 and maintain stable operation for > 105 h. Importantly, Cu─CS nanosheets shift the reaction pathway from the CO/H₂-dominated output of pristine Cu nanosheets to a C₂₊-selective profile, boosting the C₂₊:(CO + H₂) ratio from 0.7 to 4.6, an over sixfold improvement. In situ spectroscopy reveals enriched high-frequency atop-bound *CO and increased proton-transfer-active 2-HB·H₂O species, synergistically accelerating C₂₊ intermediate formation and indicating the effectiveness of molecular intermediate synergy in steering electrocatalytic pathways and product distribution.