Self-sensitized brown-TiO2 photocatalyst for highly efficient CO2 reduction under ambient conditions

Solar-powered photocatalytic CO2 reduction offers great potential for carbon fixation. Conventional widebandgap semiconductors absorb little visible light. Dye sensitization improves absorption but reduces photoelectron transfer efficiency, limiting photocatalytic performance. This work reports a self-sensitized anatase brown titanium dioxide (B-TiO2) catalyst developed through an optimized two-step method. Comprehensive experimental and computational analyses reveal that B-TiO2 extends its spectral absorption edge to 601.94 nm, over 43.69 % compared to P25, significantly enhancing visible light absorbance. The surface of B-TiO2 characterized by oxygen vacancies, Ti3+ species, and lattice defects, which are crucial for its markedly improved photocatalytic activity. Under irradiation from a 300 W Xe-lamp, the self-sensitized B-TiO2 catalyst achieves an impressive total charge-transferred electron number of 570.84 mu mol center dot g- 1 center dot h- 1 and a CO2 conversion rate of 142.05 mu mol center dot g- 1 center dot h- 1. Furthermore, the photocatalytic mechanism was investigated in detail. This innovative self-sensitized catalyst offers a promising strategy for developing high-efficiency photocatalysts, potentially advancing the field of photocatalytic CO2 reduction.