Synthesis and studies of the visible-light photocatalytic properties of near-monodisperse bi-doped TiO(2) nanospheres.

Near-monodisperse Bi-doped anatase TiO(2) nanospheres with almost uniform diameters in the range of 117 to 87 nm were prepared simply by introducing different amounts of bismuth nitrate pentahydrate into the reaction system and subsequent calcinations. X-ray diffraction, UV-visible diffuse reflectance spectra, and X-ray photoelectron spectroscopy confirm that the doped ions substitute some of the lattice titanium atoms, and furthermore, Bi(3+) and Bi(4+) ions coexist. All the Bi-doped TiO(2) samples show much better photocatalytic activity than pure TiO(2) in the degradation of rhodamine B (RhB) under the irradiation of visible light (lambda>420 nm), and, interestingly, it was found that the degradation mechanism is different from the conventional one, which has already been reported elsewhere. The detailed mechanism is discussed in this article.