Preparation of nanosized Bi3NbO7 and its visible-light photocatalytic property

A nanosized Bi3NbO7 was synthesized by the sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), UV-vis diffuse reflectance spectrum, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmet-Teller (BET). The UV-vis diffuse reflectance spectrum of the sample obtained by the sol-gel method showed a markedly blue-shift as compared to that of the sample obtained by the solid-state reaction. The band gap of the Bi3NbO7 nanoparticles was estimated to be about 2.43-2.59 eV. XPS analysis confirmed that the mixed valence bismuth existed in the crystal structure of the photocatalyst and niobium in the compound Bi3NbO7 was in the Nb5+ valence state. The as-prepared nanopowders exhibited a high photocatalytic activity in the decomposition of acid red G in water and acetone in air under visible-light irradiation, which may be assigned to larger specific surface area and the oxygen vacancies and mixed valence bismuth in the structure of Bi3NbO7.