V and N co-doped nanocrystal anatase TiO2 photocatalysts with enhanced photocatalytic activity under visible light irradiation

Vanadium and nitrogen co-doped TiO2 nanocrystal (4–5 nm) photocatalysts were prepared through direct nitridation of the controlled hydrolysis product of Tetrabutyl titanate in V (IV) ions solution. The catalysts were characterized by XRD, BET surface area, XPS, and UV–vis diffuse reflectance spectra. The co-doped TiO2 nanocrystal has a narrower band gap of 2.76 eV than V-doped TiO2 (2.91 eV) and N-doped TiO2 (2.92 eV). The co-doped TiO2 photocatalysts show enhanced photocatalytic activity for the degradation of methylene blue under visible light irradiation (λ > 420 nm) compared with V-doped TiO2 and N-doped TiO2.