Benzotrithiophene-Based Covalent Organic Frameworks with Rhenium Modified for Artificial Photosynthetic CO2 Reduction

Although covalent organic framework (COF)-based photocatalysts for CO₂ reduction reaction has been widely reported, there are still some problems such as poor visible-light absorption and low activity to realize the overall reaction of CO₂ reduction by the artificial photosynthesis strategy. Herein, anchoring the Re carbonyl complex Re(CO)₅Cl in a benzotrithiophene-based COF has been synthesized for artificial photosynthetic CO₂ reduction. The photocatalytic results demonstrate that BTT-bpy-COF-Re exhibits the highest CO₂RR activity, achieving a rate of 110.9 μmol g^-1 h^-1 for the conversion of CO₂ to CO, without the need for any sacrificial agent or photosensitizer. This performance significantly surpasses that of BTT-COF and BTT-bpy-COF. Additionally, BTT-bpy-COF-Re shows an apparent quantum efficiency of 1.17% at 420 nm. Further characterization analyses indicate that the enhanced photocatalytic activity can be attributed to improved visible-light absorption and efficient charge transfer within the Re complex-modified BTT-bpy-COF-Re system.