Synthesis and Studies of the Visible‐Light Photocatalytic Properties of Near‐Monodisperse Bi‐Doped TiO2 Nanospheres

Near‐monodisperse Bi‐doped anatase TiO₂ 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, Bi³⁺ and Bi⁴⁺ ions coexist. All the Bi‐doped TiO₂ samples show much better photocatalytic activity than pure TiO₂ in the degradation of rhodamine B (RhB) under the irradiation of visible light (λ>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.