Synthesis of δ-Bi₂O₃/Bi₂MoO₆ composites with enhanced photocatalytic activity by hydrothermal method

The δ-Bi₂O₃/Bi₂MoO₆ composites were synthesized by hydrothermal method and the microstructure and photocatalytic property were characterized. The X-ray diffraction (XRD) analysis revealed that δ-Bi₂O₃ was obtained with the existence of Bi₂MoO₆, while the product was α-Bi₂O₃ without Bi₂MoO₆ under the same experimental condition. The SEM images and the selected area electron diffraction (SAED) patterns have further verified that δ-Bi₂O₃ was deposited on Bi₂MoO₆. The X-ray photoelectron spectroscopy (XPS) spectrum confirmed that the composites were composed of δ-Bi₂O₃ and Bi₂MoO₆, while a fraction of Mo changed from Mo⁶⁺ to Mo⁵⁺. The coexistence of Mo⁵⁺/Mo⁶⁺ can be a critical factor in the formation of stable δ-Bi₂O₃ on Bi₂MoO₆. Particularly, the δ-Bi₂O₃/Bi₂MoO₆ photocatalysts possess favorable photocatalytic performance under simulated sunlight illumination since the recombination of photogenerated electrons and holes was inhibited due to the p-n junction at the interface of δ-Bi₂O₃ and Bi₂MoO₆, and the mechanism was discussed in detail.