The preparation of nitrogen-doped TiO2−xNx photocatalyst coated on hollow glass microbeads

In this paper, the effective method for nitrogen-doped TiO2−xNx photocatalyst coated on hollow glass microbeads is described, which uses titanium tetraisopropoxide [Ti(iso-OC3H7)4] as the raw materials and gaseous ammonia as a heat treatment atmosphere. The effects of heat treatment temperature and time on the photocatalytic activity of TiO2−xNx/beads are studied. The photocatalyst is characterized by the UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis and scanning electron microscopy (SEM). The results show that when the TiO2−xNx/beads is heated at 650 °C for 5 h, the photocatalytic activity of the TiO2−xNx/beads is the best. Compared with TiO2, the photoabsorption wavelength range of nitrogen-doped TiO2−xNx red shifts of about 60 nm, and the photoabsorption intensity increases as well. The photocatalytic activity of the TiO2−xNx/beads is higher than that of the TiO2/beads under visible light irradiation. The presence of nitrogen neither influences on the transformation of anatase to rutile, nor creates new crystal phases. When the TiO2−xNx/beads is heated at 650 °C for 5 h, the amount of nitrogen-doped is 0.53 wt.% in the TiO2−xNx. As the density of TiO2−xNx/beads prepared is lower than 1.0 g/cm3, it may float on water surface and use broader sunlight spectrum directly.