Photocatalytic Properties of Hollow BiFeO3 Spheres

Single-phase hollow bismuth ferrite microspheres similar to 1 mu m in diameter were synthesized by ultrasonic spray pyrolysis in a stream of air or argon. All the samples exhibited photocatalytic activity exceeding that of the standard TiO2 catalyst under UV irradiation. The samples synthesized in an argon stream exhibit catalytic activity under irradiation with a blue light. A comprehensive study showed that the appearance of the catalytic activity under the action of visible light was not associated with the powder particle morphology, oxygen defectiveness, and a change in the band gap width. An X-ray photoelectron spectroscopic study revealed decreased content of adsorbed oxygen on the surface of BiFeO3 synthesized in an argon stream. Possible mechanisms responsible for the appearance of the photocatalytic activity in the visible range are discussed.