Photocatalytic reaction characteristics of the titanium dioxide supported on the long phosphorescent phosphor by a low pressure chemical vapor deposition

This study investigated the photocatalytic behavior of titanium dioxide (TiO₂)-supported on the long phosphorescent materials. Nanocrystalline TiO₂was directly deposited on the plate of alkaline earth aluminate phosphor, CaAl₂O₄: Eu²⁺, Nd³⁺by a low pressure chemical vapor deposition (LPCVD). Photocatalytic reaction performance was examined with the decomposition of benzene gas by using a gas chromatography (GC) system under ultraviolet and visible light (λ > 410 nm) irradiations. The LPCVD TiO₂-coated phosphors showed active photocatalytic reaction under visible irradiation. The mechanism of the photocatalytic reactivity for the TiO₂-coated phosphorescent phosphor was discussed in terms of the energy band structure and phosphorescence. The coupling of TiO₂with phosphor may result in energy band bending in the junction region, which makes the TiO₂crystal at the interface to be photo-reactive under visible light irradiation. The fastest degradation of benzene gas occurred for the TiO₂-coated phosphor prepared with 1 min deposition time (∼150 nm thickness). The LPCVD TiO₂-coated phosphor is also photo-reactive under darkness through the light photons emitted from the CaAl₂O₄phosphor. In addition, the TiO₂-coated phosphorescent phosphors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).