Enhanced Intermolecular Electron Transfer in Fluorinated Metal–Organic Framework Photocatalysts for Efficient CO2 Reduction

Efficient electron transfer from photosensitizer to catalytic sites is crucial for effective artificial photosynthesis, yet it remains a significant challenge. Herein, it is reported that simple fluorination of the organic linkers in the MIL-101(Fe) photocatalyst results in a remarkable threefold increase in the photocatalytic CO 2 -to-CO conversion rate (688 µmol g −1 h −1 ) compared to the pristine counterpart (230 µmol g −1 h −1 ). It is unveiled that, instead of directly modifying the electron structure of MIL-101(Fe), the fluorinated linkers enhance the interaction between the discrete photocatalyst and photosensitizer ([Ru(bpy) 3 ] 2+ , bpy = 2,2'-bipyridine)  via hydrogen bonding, thereby facilitating their intermolecular electron transfer. Most importantly, it is also demonstrated that this performance boosting strategy can be applied to other Fe-based metal–organic frameworks (MOFs) photocatalysts such as MIL-53(Fe) and MIL-88(Fe). The present work not only underscores the fluorination of organic linkers as a generic promising approach to enhance the photocatalytic performance of MOF-based catalysts, but also holds significant implications for photosynthesis and catalytic processes reliant on intermolecular electron transfer as an important step.