In situ synthesis of an S-scheme COF-5@CsPbBr₃ heterojunction for efficient photocatalytic CO₂ reduction

The construction of heterojunction photocatalysts has attracted significant attention due to their ability to accelerate the migration of photogenerated charge carriers and suppress the recombination of photogenerated electron-hole pairs. However, photocatalytic efficiency remains constrained by insufficient redox capability. Herein, an organic-inorganic S-scheme COF-5@CsPbBr₃ heterojunction is fabricated by the in situ growth of CsPbBr₃ QDs on a COF-5 substrate, which enhances the migration efficiency of photogenerated charge carriers and the redox capacity. Compared to pristine COF-5 and CsPbBr₃ QDs, the COF-5@CsPbBr₃ heterojunction exhibited an obviously broader light-harvesting range, higher photocatalytic activity, and better stability. Furthermore, band structure analysis revealed that strong interfacial interactions between COF-5 and CsPbBr₃ QDs resulted in the formation of hybrid energy levels, facilitating the transfer of photogenerated electrons from COF-5 to CsPbBr₃ QDs. Under visible-light irradiation, the CO production rate reached 263.51 μmol g^-1 without additional photosensitizers and cocatalysts. This work demonstrates that constructing S-scheme heterojunction photocatalysts represents an effective strategy for improving the efficiency of photocatalytic CO₂ reduction.