Photocatalytic Carbon Dioxide Reduction with Rhodium‐based Catalysts in Solution and Heterogenized within Metal–Organic Frameworks

Abstract The first photosensitization of a rhodium‐based catalytic system for CO 2 reduction is reported, with formate as the sole carbon‐containing product. Formate has wide industrial applications and is seen as valuable within fuel cell technologies as well as an interesting H 2 ‐storage compound. Heterogenization of molecular rhodium catalysts is accomplished via the synthesis, post‐synthetic linker exchange, and characterization of a new metal–organic framework (MOF) Cp*Rh@UiO‐67. While the catalytic activities of the homogeneous and heterogeneous systems are found to be comparable, the MOF‐based system is more stable and selective. Furthermore it can be recycled without loss of activity. For formate production, an optimal catalyst loading of ∼10 % molar Rh incorporation is determined. Increased incorporation of rhodium catalyst favors thermal decomposition of formate into H 2 . There is no precedent for a MOF catalyzing the latter reaction so far.