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

摘要

In this study, alpha-Bi2O3/g-C3N4/beta-Bi2O3 composites were constructed by an in situ method in one step from alpha-Bi2O3 and g-C3N4. It indicates that alpha-Bi2O3 transformed to beta-Bi2O3 when it was calcined together with g-C3N4. The co-existence of alpha-Bi2O3, g-C3N4 and beta-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 alpha-Bi2O3/g-C3N4/beta-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 beta-Bi2O3 at room temperature. The enhanced photocatalytic activities of the alpha-Bi2O3/g-C3N4/beta-Bi2O3 composites were evaluated by the photocatalytic oxidation of isopropyl alcohol (IPA), and were attributed to the heterojunction formation between beta-Bi2O3 and g-C3N4.