Bismuth Oxybromide with Reasonable Photocatalytic Reduction Activity under Visible Light

The original bismuth-based oxyhalide, known as the Sillén family, is an important photocatalyst due to its high photocatalytic oxidation activity. Here, we report a bismuth-based photocatalyst, Bi₂₄O₃₁Br₁₀, with reasonable reduction activity. The photoreduction capability of Bi₂₄O₃₁Br₁₀ in H₂ evolution from water reduction is 133.9 μmol after 40 h under visible light irradiation. Bi₂₄O₃₁Br₁₀ presents the highest activity among Bi₂O₃, BiOBr, and Bi₂₄O₃₁Br₁₀ in photocatalytic reduction of the Cr (VI) test, and Cr (VI) ions are totally removed in 40 min. The Mott–Schottky test shows the bottom of the conduction band fits the electric potential requirements for splitting water to H₂. First-principles calculations indicate the conduction band of Bi₂₄O₃₁Br₁₀ mainly consists of hybridized Bi 6p and Br 4s orbitals, which may contribute to the uplifting of the conduction band