10BaF2:NaF, Na3AlF6/TiO2 composite as a novel visible-light-driven photocatalyst based on upconversion emission

A rare-earth free upconversion luminescent material, 10BaF(2):NaF, Na3AlF6, is synthesized by a hydrothermal method. The study of fluorescent spectrum indicates that it can convert visible light (550 nm-610 nm) into ultraviolet light (290 nm-350 nm), and two emission peaks at 304 nm and 324 nm are observed under the excitation of 583 nm at room temperature. Subsequently, 10BaF(2):NaF, Na3AlF6/TiO2 composite photocatalyst is prepared and its catalytic activity is evaluated by the photocatalytic reduction of CO2 under visible light irradiation (lambda>515 nm). The results show that 10BaF(2):NaF, Na3AlF6/TiO2 is a more effective photocatalyst for CO2 reduction than pure TiO2, their corresponding methanol yields are 179 and 0 mu mol/g-cat under the same conditions. Additionally, the mechanism of photocatalytic reduction of CO2 on 10BaF(2):NaF, Na3AlF6/TiO2 is proposed.