Dual Metallosalen‐Based Covalent Organic Frameworks for Artificial Photosynthetic Diluted CO 2 Reduction

Abstract Directly converting CO 2 in flue gas using artificial photosynthetic technology represents a promising green approach for CO 2 resource utilization. However, it remains a great challenge to achieve efficient reduction of CO 2 from flue gas due to the decreased activity of photocatalysts in diluted CO 2 atmosphere. Herein, we designed and synthesized a series of dual metallosalen‐based covalent organic frameworks (MM‐Salen‐COFs, M: Zn, Ni, Cu) for artificial photosynthetic diluted CO 2 reduction and confirmed their advantage in comparison to that of single metal M‐Salen‐COFs. As a results, the ZnZn‐Salen‐COF with dual Zn sites exhibits a prominent visible‐light‐driven CO 2 ‐to‐CO conversion rate of 150.9 μmol g −1 h −1 under pure CO 2 atmosphere, which is ~6 times higher than that of single metal Zn‐Salen‐COF. Notably, the dual metal ZnZn‐Salen‐COF still displays efficient CO 2 conversion activity of 102.1 μmol g −1 h −1 under diluted CO 2 atmosphere from simulated flue gas conditions (15 % CO 2 ), which is a record high activity among COFs‐ and MOFs‐based photocatalysts under the same reaction conditions. Further investigations and theoretical calculations suggest that the synergistic effect between the neighboring dual metal sites in the ZnZn‐Salen‐COF facilitates low concentration CO 2 adsorption and activation, thereby lowering the energy barrier of the rate‐determining step.