Regulation of Electrocatalytic Behavior by Axial Oxygen Enhances the Catalytic Activity of CoN 4 Sites for CO 2 Reduction.

Recent studies have found that the existence of oxygen around the active sites may be essential for efficient electrochemical CO 2 -to-CO conversion. Hence, this work proposes the modulation of oxygen coordination and investigates the as-induced catalytic behavior in CO 2 RR. It designs and synthesizes conjugated phthalocyanine frameworks catalysts (CPF-Co) with abundant CoN 4 centers as an active source, and subsequently modifies the electronic structure of CPF-Co by introducing graphene oxide (GO) with oxygen-rich functional groups. A systematic study reveals that the axial coordination between oxygen and the catalytic sites could form an optimized O-CoN 4 structure to break the electron distribution symmetry of Co, thus reducing the energy barrier to the activation of CO 2 to COOH*. Meanwhile, by adjusting the content of oxygen, the proper supports can also facilitate the charge transfer efficiency between the matrix layer and the catalytic sites. The optimized CPF-Co@LGO exhibits a high TOF value (2.81 s -1 ), CO selectivity (97.6%) as well as stability (24 h) at 21 mA cm -2 current density. This work reveals the modulation of oxygen during CO 2 RR and provides a novel strategy for the design of efficient electrocatalysts, which may inspire new exploration and principles for CO 2 RR.