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

Abstract 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 CO₂‐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.