Preparation of NaxBayBiO3·nH2O and their photooxidation characteristic under visible-light irradiation

NaxBayBiO3·nH2O (NBBO) has been prepared using a commercial NaBiO3·nH2O (NBO) as a starting material with a hydrothermal iron-exchange reaction. As-synthesized samples were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible light (UV–vis) absorbance spectra, thermogravimetry-differential scanning calorimetry (TG-DSC) and X-ray photoelectron spectroscopy (XPS) techniques. The photooxidation decomposition of phenol over NBBO has been carried out under visible-light irradiation (λ > 400 nm). The result revealed that the NBBO showed considerable photooxidation activity for phenol degradation in the range of visible light. The result of reusability indicated the structure of NBBO was instable, which was changed to Bi2O2CO3 in the photooxidation process, although photooxidation activity kept high in three runs. This study has provided useful information for the development of new bismuthate photocatalyst with higher photoactivity under visible-light irradiation.