Visible-Light Photocatalytic Activity of S‑Doped α‑Bi₂O₃

A batch of S-doped α-Bi₂O₃ and pure α-Bi₂O₃ were prepared by a simple chemical preparation method using thiourea as sulfur source, and the S-doped α-Bi₂O₃ samples promoted the activity in the visible light range in terms of photocatalytic degradation of RhB. The photocatalysts were characterized by X-ray diffraction, scanning electron microscope, UV–vis diffuse reflectance spectrophotometer, X-ray photoelectron spectroscopy, and X-ray absorption near-edge structure. It is surprisingly found that the S atom substitutes on the Bi site rather than substituting on the O site. Further work on the first-principle calculations confirms the S substitution and reflects the differences of electronic structures between S-doped α-Bi₂O₃ and pure α-Bi₂O₃. The possible mechanism for the enhancement of visible-light photocatalysis by S doping is proposed in terms of both experimental results and calculations.