Promoting\nWater Activation via Molecular Engineering\nEnables Efficient Asymmetric C–C Coupling during CO<sub>2</sub> Electroreduction

Water\nactivation plays a crucial role in CO<sub>2</sub> reduction,\nbut improving the electrocatalytic performance through controlled\nwater activation presents a significant challenge. Herein, we achieved\nelectrochemical CO<sub>2</sub> reduction to ethene and ethanol with\nhigh selectivity by promoting water dissociation and asymmetric C–C\ncoupling by engineering Cu surfaces with N–H-rich molecules.\nDirect spectroscopic evidence, coupled with density functional theory\ncalculations, demonstrates that the N–H-rich molecules accelerate\ninterfacial water dissociation via hydrogen-bond interactions, and\nthe generated hydrogen species facilitate the conversion of *CO to\n*CHO. This enables the efficient asymmetric *CHO–*CO coupling\nto C<sub>2</sub> products with a faradaic efficiency (FE) ∼\n30% higher than that of the unmodified catalyst. Moreover, by adjustment\nof the relative *CHO/*CO coverage via Cu surface facet regulation,\nthe selectivity can be entirely switched between C<sub>2</sub> products\nand CH<sub>4</sub>. These mechanistic insights further guided the\ndevelopment of a more efficient catalyst by directly modifying Cu<sub>2</sub>O nanocubes with the N–H-rich molecule, achieving remarkable\nC<sub>2</sub> product (mainly ethene and ethanol) FEs of 85.7% at\na current density of 800 mA cm<sup>–2</sup> and excellent stability\nunder nearing industrial conditions. This study advances our understanding\nof the CO<sub>2</sub> reduction mechanisms and offers an effective\nand general strategy for enhancing electrocatalytic performance by\naccelerating water dissociation.