Fabrication of NIR-Responsive NaYF_4:Yb,Tm/Anatase TiO_2 Composite Aerogel

摘要

3-dimensional interconnected network structure of TiO_2 aerogel has attracted considerable attention to solve environmental issues due to an advanced oxidation process which uses abundant sunlight for the complete minimization of toxic pollutants. The TiO_2 aerogel with high specific surface area, large pores, and low density has a potential to be used as photocatalyst for air and water purification. Nonetheless, due to the larger band gap, TiO_2 semiconductor photocatalysts possess high oxidizing properties under UV light only which occupies 5% of solar energy. To expand the absorption spectrum of TiO_2 aerogel under solar irradiation, the NaYF_4:Yb,Tm nanoparticles (NPs) are introduced into the TiO_2 aerogel matrix structure. The morphology and crystal structure of the composite aerogel are investigated by transmission electron microscopy and X-ray diffraction, respectively. The particle size of NaYF_4: Yb,Tm NPs is approximately 40 nm and the crystallite size of TiO_2 is around 10 nm. In addition, the NaYF_4:Yb,Tm NPs are enclosed by anatase phase of TiO_2 aerogel. The NaYF_4: Yb,Tm NPs which exist in the TiO_2 aerogel has a capability of transferring NIR light to UV region.