Photocatalytic behavior of the coupling of TiO2-phosphorescent materials using CVD

Abstract

This study investigated the photocatalytic behavior of titanium dioxide (TiO2)-coated phosphorescent materials. Nanocrystal- line TiO 2 was directly deposited on the alkaline earth aluminate phosphor of CaAl2O4:Eu2+,Nd3+ by chemical vapor deposition (CVD) and its photocatalytic behavior was examined with the degradation of methylene blue (MB) aqueous solution under visible light irradiation. With increasing deposition temperature, the CVD TiO2 thin film exhibited a columnar structure and preferred crystal growth in the (112) orientation. The mechanism of the photocatalytic reactivity for the coupling of TiO2- phosphorescent materials was discussed in terms of the energy band structure and phosphorescence. The coupling of TiO2 with phosphor may result in energy band bending in the junction region, which rendered the TiO2 crystal at the interface photo-reactive under visible light irradiation. The CVD TiO2-coated phosphors showed active photocatalytic reaction under visible irradiation. In addition, the TiO 2-coated phosphorescent materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). © 2009 The Ceramic Society of Japan. All rights reserved.