A Cu I Cluster-Based Covalent Metal-Organic Framework as a Photocatalyst for Efficient Visible-Light-Driven Reduction of CO 2 .

The application of solar energy to convert CO into high-value chemicals and fuels has been considered a highly desirable approach to relieving the greenhouse effect and energy crisis. However, the exploration of appropriate photocatalysts remains a major challenge. Combining the respective advantages of covalent organic frameworks and metal-organic frameworks to construct covalent metal-organic frameworks (CMOFs) can be a valid strategy to provide efficient, reliable, and eco-friendly photocatalysts. In this study, a Cu cluster-based CMOF (JNM-2) is used as a photocatalyst for CO photoreduction under visible-light irradiation. JNM-2 exhibits remarkable efficiency in photocatalytic CO reduction with high production rates of HCOOH (9019 μmol g  h ) and CO (835 μmol g  h ). The active center, reaction intermediates, and product generation pathways are elucidated by in situ DRIFTS and DFT calculations. This work demonstrates the tremendous possibilities of CMOFs as photocatalysts for CO reduction and provides profound insights into the mechanism of CO conversion into HCOOH/CO by using a molecularly accurate structural model.