Covalent organic framework with bioinspired N,S-anchored single atom sites for photocatalytic CO2 reduction reaction

Photocatalytic CO2 reduction reaction (CO2RR) has promising potential to address global energy and environmental challenges but is severely limited by sluggish kinetics and poor selectivity, where the chemical microenvironments and electronic structures of the catalytic center play pivotal roles. Herein, inspired by carbon monoxide dehydrogenase, which can accelerate CO2 to CO reduction, we delicately design a covalent organic framework (THD-COF) with bioinspired N,S-coordination sites from thiophene and imine modules on the skeleton and construct Co-THD-COF by anchoring single Co atoms on the N,S-sites. Under visible light, employing binary mixed sacrificial agents, with the help of photosensitizer [Ru(bpy)3]Cl2·6H2O, Co-THD-COF displays dramatically enhanced photocatalytic CO2RR activity, exhibiting an astounding CO generating rate of 9357 μmol g−1h−1 with the selectivity of 95.1 %. Additionally, Co-THD-COF can photocatalyze CO2 conversion smoothly in real seawater without loss of CO selectivity. Experimental and computational analysis further manifest that the single Co atom is the catalytic active center. Co-THD-COF significantly promotes CO2 adsorption and activation, charge separation dynamics, and is also beneficial to the formation of the crucial *COOH intermediates. The current study offers deep insights into the effective conversion of CO2 and enlightens the design of novel bioinspired coordination sites for single-atom photocatalysts.