Reaction Mechanisms of Well‐Defined Metal–N₄ Sites in Electrocatalytic CO₂ Reduction

Abstract

Electrocatalytic CO₂ reduction to CO emerges as a potential route of utilizing emitted CO₂ . Metal-N-C hybrid structures have shown unique activities, however, the active centers and reaction mechanisms remain unclear because of the ambiguity in true atomic structures for the prepared catalysts. Herein, combining density-functional theory calculations and experimental studies, the reaction mechanisms for well-defined metal-N₄ sites were explored using metal phthalocyanines as model catalysts. The theoretical calculations reveal that cobalt phthalocyanine exhibits the optimum activity for CO₂ reduction to CO because of the moderate *CO binding energy at the Co site, which accommodates the *COOH formation and the *CO desorption. It is further confirmed by experimental studies, where cobalt phthalocyanine delivers the best performance, with a maximal CO Faradaic efficiency reaching 99 %, and maintains stable performance for over 60 hours.