Integrating Single Atoms with Different Microenvironments into One Porous Organic Polymer for Efficient Photocatalytic CO2 Reduction

Abstract The precise identification of single‐atom catalysts (SACs) activity and boosting their efficiency toward CO 2 conversion is imperative yet quite challenging. Herein, for the first time a series of porous organic polymers is designed and prepared simultaneously, containing well‐defined M–N 4 and M–N 2 O 2 single‐atom sites. Such a strategy not only offers multiactive sites to promote the catalytic efficiency but also provides a more direct chance to identify the metal center activity. The CO 2 photoreduction results indicate that the introduction of salphen unit with Ni–N 2 O 2 catalytic centers into pristine phthalocyanine‐based Ni–N 4 framework achieves remarkable CO generation ability (7.77 mmol g –1 ) with a high selectivity of 96% over H 2 . In combination with control experiments, as well as theoretical studies, the Ni–N 2 O 2 moiety is evidenced as a more active site for CO 2 RR compared with the traditional Ni–N 4 moiety, which can be ascribed to the M–N 2 O 2 active sites effectively reducing the energy barrier, facilitating the adsorption of reaction radicals *COOH, and improving the charge transportation. This work might shed some light on designing more efficient SACs toward CO 2 reduction through modification of their coordination environments.