In situ construction of α-Bi2O3/g-C3N4/β-Bi2O3 composites and their highly efficient photocatalytic performances

Abstract

In this study, α-Bi₂O₃/g-C₃N₄/β-Bi₂O₃ composites were constructed by an in situ method in one step from α-Bi₂O₃ and g-C₃N₄. It indicates that α-Bi₂O₃ transformed to β-Bi₂O₃ when it was calcined together with g-C₃N₄. The co-existence of α-Bi₂O₃, g-C₃N₄ and β-Bi₂O₃ was proved by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and high-resolution transmission electron microscopy (HRTEM). The energy band structures and optical properties were studied by ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) and valence band X-ray photoelectron spectroscopy (VB-XPS). The in situ formation mechanism of the α-Bi₂O₃/g-C₃N₄/β-Bi₂O₃ composites in one step was studied using the samples’ surface chemical states, which were measured by X-ray photoelectron spectroscopy (XPS). The results show that the surface covered or coordinated g-C₃N₄ and CO₃²⁻ which has a promotional effect on the stability of β-Bi₂O₃ at room temperature. The enhanced photocatalytic activities of the α-Bi₂O₃/g-C₃N₄/β-Bi₂O₃ composites were evaluated by the photocatalytic oxidation of isopropyl alcohol (IPA), and were attributed to the heterojunction formation between β-Bi₂O₃ and g-C₃N₄.