ZrO₂-Modified Mesoporous Nanocrystalline TiO_2-xN_x as Efficient Visible Light Photocatalysts

Mesoporous nanocrystalline TiO_2-xN_x and TiO_2-xN_x/ZrO₂ visible-light photocatalysts have been prepared by a sol−gel method. The photocatalysts were characterized by XRD, N₂ adsorption−desorption, TEM, XPS, UV/Vis, and IR spectroscopy. The photocatalytic activity of the samples was evaluated by the decomposition of ethylene in air under visible light (λ > 450 nm) illumination. Results revealed that nitrogen was doped into the lattice of TiO₂ by the thermal treatment of NH₃-adsorbed TiO₂ hydrous gels, converting the TiO₂ into a visible-light responsive catalyst. The introduction of ZrO₂ into TiO_2-xN_x considerably inhibits the undesirable crystal growth during calcination. Consequently, the ZrO₂-modified TiO_2-xN_x displays higher porosity, higher specific surface area, and an improved thermal stability over the corresponding unmodified TiO_2-xN_x samples.