A bismuth rich hollow Bi4O5Br2 photocatalyst enables dramatic CO2 reduction activity

The insufficient separation of photogenerated charge carriers and faint CO2 capture remains the major obstacles for photocatalytic conversion of CO2 into solar fuel. Rational design of semiconductor photocatalysts with unique structures may be promising to break this bottleneck. Herein, bismuth rich Bi4O5B2 hollow microspheres are designed as a robust photocatalyst for efficient CO2 reduction. Thanks to the bismuth rich strategy, the highly dispersed band structure and the elevated conduction band (CB) potential facilitate the charge transfer and photoreduction ability. Meanwhile, hollow structure provides the large specific area and creates a resonance in its interior to enhance the CO2 adsorption and activation. Benefiting from the collaborative promotion effect, the local charge arrangement and electronic structure are tuned so as to an exceptional efficiency of photocatalytic CO2 conversion into CO (3.16 μmol g−1 h−1) and CH4 (0.5 μmol g−1 h−1) is attained over hollow Bi4O5Br2, which is superior to that of solid Bi4O5Br2 and BiOBr, as well as other reported Bi-based photocatalysts. This work paves new opportunities for exploring high-efficiency CO2 photoreduction catalysts.