Highly active V–TiO2 for photocatalytic degradation of methyl orange

Two kinds of vanadium-doped TiO2 powders photocatalysts were prepared by sol–gel method in even doping and uneven doping modes, and were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–vis diffuse reflectance spectroscopy (DRS). The photocatalytic activity of TiO2 photocatalysts doped by vanadium evenly with lower dopant level up to 0.002mol.% is better than that of undoped TiO2, while with higher dopant level the activity is worse. TiO2 photocatalysts doped by vanadium unevenly with a p–n junction semiconductor structure, was shown to have a much higher photocatalytic destruction rate than that of TiO2 photocatalysts doped by vanadium evenly and undoped TiO2, which is ascribed mainly to the electrostatic-field-driven electron–hole separation in TiO2 particles doped by vanadium unevenly.