Enhancing CO₂ Electroreduction to C2 Products on Metal-Nitrogen Sites by Regulating H₂O Dissociation

Water dissociation remarkably affects the CO₂ reduction to CO and HCOOH, but whether it is effective for two-carbon product formation on M-N-containing catalysts is still ambiguous. Herein, by using a fluorinated metal phthalocyanine (MPc-F) as the M-N₄-based model electrocatalyst, experimental and theoretical results reveal that the H₂O-dissociation-induced active H species decrease the overpotential of the *CO hydrogenation to *CHO and facilitate the C-C coupling between *CHO and neighboring CO. Such an effect is strengthened by an increase in the *CO binding strength on the metal center. By introducing CuPc as the H₂O dissociation catalyst into MPc-F (MPc-F/CuPc) to accurately regulate the H₂O dissociation, the faradic efficiency of C2 products on FePc-F/CuPc and MnPc-F/CuPc increases from 0% (FePc-F and MnPc-F) to 26 and 36%, respectively. This work develops a novel strategy for enhancing the selectivity of M-N-containing catalysts to C2 products and reveals the correlation between H₂O dissociation and C2 product formation.