Fabrication of Bi2O3/In2O3 p-n heterojunction with enhanced photocatalytic activity by efficient interfacial charge transfer

Facilitating the separation of photogenerated charges is a crucial process in photocatalytic degradation of pollutants. In this study, Bi₂O₃/In₂O₃ composites were prepared using a co-precipitation method and subsequently calcined at 400 ℃ for 1 h. The Mott-Schottky curves confirmed a p(Bi₂O₃)-n(In₂O₃) heterojunction was yielded. Due to the significant difference in Fermi levels between Bi₂O₃ and In₂O₃, an internal electric field was established at the interface, with field lines directed from In₂O₃ to Bi₂O₃. Under illumination, the excited electrons accumulated in the conduction band (CB) of In₂O₃, while holes gathered in the valence band (VB) of Bi₂O₃, promoting charge separation and enhancing quantum efficiency. The composite material exhibited the highest photocatalytic activity when the atomic percentage of Bi to In was 1:1, with the first-order reaction rate constant of BI-1 increasing to 0.0149 min⁻¹, which is 4.3 and 4.4 multiples higher than that of pure In₂O₃ and pure Bi₂O₃. Recycling experiments demonstrated that the photocatalytic composite possesses good reusability and structural stability.