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.