Structure and photocatalytic property of Mo-doped TiO2 nanoparticles

Mo-doped TiO2 nanoparticles were prepared by sol-gel technique. The as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), TEM and FE-SEM. UV–Vis absorption spectrum and the Kubelka–Munk transformation were used to measure the absorption curves and band gap. Their photocatalytic activities were evaluated by the photo-degradation of methyl orange (MO) under irradiation of UV–Visible light and simulated solar light. The results show that Mo6 + ions have been doped into anatase TiO2 lattice. Mo-doping in TiO2 narrows the band gap (from 3.19 eV of TiO2 to 3.05 eV of Ti0.97Mo0.03O2) and efficiently increases the optical absorption in visible range. The density functional theory (DFT) calculation of Ti1-xMoxO2 (x = 0.02) explains that Mo atom behaves as an abundant donor in TiO2 and can narrow the band gap, since it has two more valence electrons. Therefore, Mo-doped TiO2 nanoparticles exhibit improved photo-degradation ability and the optimal ability of TiO2 nanocrystals is achieved by 2.0 at% Mo-doping.