Mechanochemical syntheses of bismuth oxybromides BixOyBrz as visible-light responsive photocatalyts for the degradation of bisphenol A

Bismuth oxyhalides are a group of materials receiving wide attentions because of various interesting properties. Bismuth salts even of nitrate are not stable and easy to hydrolyze to give some intermediate phases during the hydrothermal synthesis. A simple novel method for the preparation of a series of bismuth oxybromide materials based on ball milling bismuth oxide and bromide, has been provided in this article. A set of analytical methods of X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, ultraviolet-visible spectroscopy and photoluminescence measurement were performed to characterize the crystal phase, morphology, optical properties and chemical constitution of as-prepared samples. Quantitative measurement by photodegrading bisphenol A under visible light irradiation confirmed the efficient visible-light response of the mechanochemically synthesized bismuth oxybromides. The results demonstrated that BixOyBrz which O/Br atomic ratio between 1 and 3.1 could be easily synthesized by one-step mechanochemical approach without the observable existences of impurities. Photocatalytic activity of the prepared sample was closely dependent on the O/Br ratio and oxygen-rich was beneficial to raise the activity. This research opened a new idea to prepare bismuth semiconductors efficiently and environment-friendlily.