Post-modification of metal-organic framework for improved CO2 photoreduction efficiency

Utilizing metal-organic frameworks (MOFs) to design photocatalysts for CO2 reduction catalysts is an excellent idea but currently restricted by the relatively low activity. Enhancing CO2 affinity and tuning the oxidation state of metal clusters in MOFs might be a solution to improve the catalytic performance. Herein, the Cl-bridge atoms in the metal clusters of a cobalt MOF were easily exchanged with OH−, which simultaneously oxidized a portion of Co(II) to Co(III) and resulted in a much enhanced photocatalytic activity for CO2 reduction. In contrast, the original framework does not exhibit such superior activity. Comprehensive characterizations on their physicochemical properties revealed that the introduction of hydroxyl group not only greatly increases the CO2 affinity but also alters the oxidation state of metal clusters, resulting in significantly improved photocatalytic activities for CO2 reduction. This work provides important insight into the design of efficient photocatalysts.