Bi2O3/BiFeO3 heterostructure: preparation, characterization, and photocatalytic activity

Bi2O3/BiFeO3 composite was successfully fabricated by a conventional sol–gel method and structural properties were characterized based on X-ray diffractometer, scanning electron microscope, transmission electron microscope, energy-dispersive X-ray analyzer, nitrogen adsorption–desorption measurement, and UV–visible diffuse reflectance spectroscopy. Bi2O3/BiFeO3 had a good absorption for visible light, which was benefit to photocatalytic activity. The highest degradation efficiency was obtained when the content of Bi2O3 in Bi2O3/BiFeO3 was 63.9%. Effect of experimental conditions was investigated, and the highest photocatalytic activity of Bi2O3/BiFeO3 was observed at photocatalyst dosage of 0.5 g/L, initial BPA concentration of 10 mg/L, and solution pH of 6.3. Bi2O3/BiFeO3 photocatalyst exhibited enhanced photocatalytic activity for BPA, and the reaction rate constant over Bi2O3/BiFeO3 composite was 2.23, 3.65, and 8.71 times higher than that of BiFeO3, Bi2O3 and commercial TiO2 (P25), respectively. Bi2O3/BiFeO3 showed high photocatalytic activity after three cycles, suggesting that it was a stable photocatalyst. The possible photocatalytic mechanism has been discussed on the basis of the theoretical calculation and the experimental results. The hydroxyl and superoxide radicals together with photogenerated holes played significant roles in the photocatalytic reaction.