Preparation of V or W Doped TiO₂ Coating Hollow Glass Spheres and Photocatalytic Characterization

Abstract

To improve the photocatalytic activity of TiO₂ coated hollow volcanic glass spheres, vanadium or tungsten hydroxide was doped on the surface of volcanic glass in the aqueous solution of NH₄VO₃ or 5(NH₄)₂O·12WO₃·5H₂O. The volcanic glass was ballooned by heat treatment in temperature ranges of 960 ∼ 1,000 °C, and these hydroxides were translated into metallic oxides in this process.
On increasing the vanadium loading, the crystal size of anatase TiO₂ on the surface of volcanic glass spheres increased and the phase transformation of anatase to rutile occurred. As the result, the removal rate of NO gas was decreased. Whereas, when the tungsten was doped, there was not almost the change of the crystal size of anatase TiO₂ and the phase transformation of anatase to rutile was not observed. The crystal size of anatase TiO₂ appeared about 12nm and the removal rate of NO gas was increased with raising the tungsten loading. The maximum removal rate of NO gas was observed with adding the tungsten of 0.54 wt%.