Crystalline metallic Au nanoparticle-loaded α-Bi2O3 microrods for improved photocatalysis

Crystalline metallic Au nanoparticles were loaded on alpha-Bi2O3 microrods (Au/alpha-Bi2O3) using an Au deposition-precipitation method. The prepared samples were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Upon visible light irradiation, the Au/alpha-Bi2O3 exhibits much higher photocatalytic activities than the pure alpha-Bi2O3 for the degradation of Rhodamine B and 2,4-dichlorophenol in aqueous solution. The role of the Au and the paths of electron transport in the photocatalysis of the Au/alpha-Bi2O3 were investigated and discussed in detail based on the analysis of the photo-generated hydroxyl radicals ((OH)-O-center dot) and hydrogen peroxide (H2O2) in the visible light irradiated suspension of pure alpha-Bi2O3 and Au/alpha-Bi2O3. The result reveals that the Au loaded on alpha-Bi2O3 plays a critical role in the separation of the electron and hole pairs by accumulating the electrons from the excited alpha-Bi2O3, which is responsible for the enhanced photocatalytic activity.