Efficient Photocatalytic Removal of Contaminant by Bi3NbxTa1−xO7 Nanoparticles under Visible Light Irradiation

Nanosized Bi3NbxTa1−xO7 photocatalysts were prepared by a facile and low-cost sol−gel method using stable, less toxic Ta2O5, Nb2O5, and Bi(NO3)3·5H2O as the raw materials. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, Fourier transformation infrared spectroscopy, X-ray photoelectron spectroscopy, and UV−vis diffuse reflectance spectroscopy. The Bi3NbxTa1−xO7 nanoparticles exhibited an efficient photocatalytic activity in the decomposition of acid red G (ARG) dye solution under visible light irradiation. Besides decoloring, the typical sample Bi3Nb0.6Ta0.4O7 also showed an excellent photocatalytic property for the removal of the cyanotoxin, microcystin-LR (MC-LR, an emerging contaminant from the Contaminant Candidate Lists (CCLs 1-3) of the USEPA). The excellent visible light photocatalytic activity of the samples was mainly attributed to their narrow band gaps, small particle size, and the oxygen vacancies on the surface of the catalysts. According to experimental results, a possible mechanism of the photocatalysis over Bi3NbxTa1−xO7 was proposed.