Tailoring Co Coordination Mode in COF Nanosheets for Efficient Solar‐Driven Reduction of Non‐Neat CO 2 into Syngas

Abstract Photocatalytic conversion of CO 2 into syngas is a promising approach to solving energy and environmental challenges. However, the current studies are mainly conducted by using neat CO 2 where CO 2 enrichment and purification is an energy‐intensive process. Herein, we report a Co‐COOH‐COF with an asymmetric tridentate ligand for syngas synthesis from different contents of CO 2 . The nanosheets of the resulting champion catalyst, Co 17.7 ‐COOH‐COF enable an outstanding syngas production rate of 151.1 mmol g −1 h −1 from neat CO 2 and 180.5 mmol g −1 h −1 from 40 vol% CO 2 under visible light, while it is up to 112.3 mmol g −1 h −1 from neat CO 2 and 116.0 mmol g −1 h −1 from 40 vol% CO 2 under natural sunlight, which surpasses most of the previously reported state‐of‐the‐art photocatalysts. Impressively, the catalyst also exhibits a widely and continuously adjustable CO/H 2 molar ratio from 4:1 to 1:21. Experimental and theoretical studies indicate that the asymmetric tridentate ligand with carboxyl groups increases Co loading in the covalent organic frame (COF) by the formation of atomically dispersed N–Co–O 4 sites and enhances dissociation of water and CO 2 adsorption by hydrogen bonding, thus facilitating CO 2 transformation and hydrogen evolution. This work presents a new pathway for the design of high‐performance catalysts for the photoreduction of CO 2 to syngas.