Ultraviolet upconversion luminescence in Y₂O₃:Yb3+,Tm3+ nanocrystals and its application in photocatalysis

摘要

Infrared-to-ultraviolet upconversion luminescence agent Y₂O₃:Yb3+,Tm3+ was prepared by a combustion method using citrate as a fuel/reductant. The prepared sample was characterized by X-ray diffraction, SEM, and fluorescence spectrophotometer. Two unusual 1I₆ → 3H₆ (~297 nm) and 1D₂ → 3H₆ (~363 nm) emissions from Tm3+ ions were observed at room temperature under 980-nm laser excitation. The change of upconversion emission intensity depending on the Yb3+ concentrations was discussed. The results showed that modest Yb3+ doping could make the upconversion emission of Tm3+ intense, and high Yb3+ concentrations might lead to fluorescence quenching. Moreover, the influence of ultraviolet upconversion luminescence on the photodegradation of methyl orange aqueous solution under solar light irradiation in the presence of TiO₂ catalyst doped with Y₂O₃:Yb3+,Tm3+ was also investigated. It was concluded from the experiment of this study that TiO₂/Y₂O₃:Yb3+,Tm3+ composite had higher photocatalytic activity than pure TiO₂ under solar light. This study would make TiO₂ utilize sunlight more efficiently and accelerate the practical application of photocatalytic technology in water treatment region.