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 0.002 mol.% 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.