Tailoring Co Coordination Mode in COF Nanosheets for Efficient Solar‐driven Reduction of Non‐neat CO2 into Syngas

Photocatalytic conversion of CO2 into syngas is a promising approach to solving energy and environmental challenges. However, the current studies are mainly conducted by using neat CO2 where CO2 enrichment and purification is an energy‐intensive process. Herein, we report a Co‐COOH‐COF with asymmetric tridentate ligand for syngas synthesis from different contents of CO2. The nanosheets of the resulting champion catalyst Co17.7‐COOH‐COF enable an outstanding syngas production rate of 151.1 mmol g−1 h−1 from neat CO2 and 180.5 mmol g−1 h−1 from 40 vol% CO2 under visible light, while it is up to 112.3 mmol g−1 h−1 from neat CO2 and 116.0 mmol g−1 h−1 from 40 vol% CO2 under natural sunlight, which surpasses most of the previously reported state‐of‐the‐art photocatalysts. Impressively, the catalyst also exhibits widely and continuously adjustable CO/H2 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 COF by formation of atomic dispersed N‐Co‐O4 sites, enhances dissociation of water and CO2 adsorption by hydrogen bonding, thus facilitating CO2 transformation and hydrogen evolution. This work presents a new pathway for design of high‐performance catalysts for the photoreduction CO2 to syngas.