Regulating the oxidation state of copper centers in metal-organic frameworks for enhanced carbon dioxide photoreduction

Metal-organic frameworks (MOFs) are promising artificial photocatalysts for photocatalytic carbon dioxide conversion due to their incorporated catalytic metal centers and intriguing structural diversity. Only a limited number of MOFs have been reported as artificial photocatalysts, however, posing a significant challenge in attaining optimal performance from these catalysts. Herein, we present a strategy for enhancing the photocatalytic performance of a Cu–DHTP MOF structure through coordination engineering. Our findings suggest that the lower oxidation state of copper active sites in Cu–DHTP leads to changes in its electronic structure. These changes enable improved absorption of solar light, faster separation of charges, and enhanced adsorption of carbon dioxide. Under solar light, Cu–DHTP exhibits a carbon monoxide production rate of 10.55 μmol g−1 h−1 with nearly 100% selectivity while requiring no co-catalysts or sacrificial agents. This rate is 11.34 times higher than the comparable MOF sample, which contains a higher oxidation copper center.