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, Bi₂₄O ₃₁Br₁₀, 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 Bi ₂₄O₃₁Br₁₀ 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.