Boosting Photocatalytic CO₂ Reduction Over In-Doped Bi₄O₅Br₂: Synergistic Bandgap Engineering and Charge Separation

Photocatalytic CO₂ reduction represents a viable approach to achieving carbon neutrality through fuel production. Nonetheless, the practical deployment of photocatalysts is frequently hampered by the rapid recombination of photogenerated charge carriers. In this investigation, a one-pot solvothermal method was used to synthesize In-doped Bi₄O₅Br₂ photocatalysts. Comprehensive characterizations demonstrate that the electronic structure is effectively modulated by In³⁺ doping, resulting in a narrowed bandgap. Crucially, the recombination of photogenerated electron-hole pairs is suppressed through the introduction of dopant-induced energy levels. The 15In-Bi₄O₅Br₂ sample displays the optimal photocatalytic CO₂ reduction activity, producing CO at a rate of 4.67 µmol g^-1 h^-1, which is approximately 2.3 times higher than that of unmodified Bi₄O₅Br₂. This remarkable enhancement is attributed to the synergistic effects of an optimized band structure and improved charge separation efficiency induced by In doping. This work provides valuable insights into the rational design of bismuth-based materials for sustainable CO₂ conversion.