Preparation of nanometer TiO₂ doped with upconversion luminescence agent and investigation on degradation of ethyl violet using visible light

A novel upconversion luminescence agent 40CdF₂ · 60BaF₂ · 1.6Er₂O₃ was synthesized and the fluorescent spectrum was determined. This upconversion luminescence agent can emit five upconversion fluorescent peaks whose wavelengths are all below 387nm under the excitation of 488 nm visible light. This upconversion luminescence agent was mixed into nanometer TiO₂ powder by ultrasonic dispersion and the doped nanometer TiO₂ photocatalyst utilizing visible light was prepared. The doped TiO₂ powder was charactered by XRD and TEM and its photocatalytic activity was checked through the photocatalytic degradation of ethyl violet dye as a model compound under the visible light irradiation emitted by three basic color lamp. Otherwise, in order to compare the photocatalytic activities the same experiment was carried out for undoped photocatalytic TiO₂ powder. The degradation ratio of ethyl violet dye in the presence of doped nanometer TiO₂ powder reached 99.68% under visible light irradiation at 12.0 h which was obviously higher than the corresponding degradation ratio in the presence of undoped nanometer TiO₂ powder, which indicate that the upconversion luminescence agent prepared as dopant can effectively turn visible lights to ultraviolet lights which are absorbed by nanometer TiO₂ particles and produce the electron-cavity pairs.