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

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).