STRUCTURES AND PHOTOCATALYSIS OF NANOCRYSTALLINE TiO_2 POWDERS AND THIN FILMS DERIVED BY SOL-GEL PROCESS

摘要

In this paper, nanocrystalline TiO_2 powders and thin films were prepared by sol-gel process. The samples were annealed at different temperatures, and the structures of the samples were studied by thermogravimetric (TG)analyzer, differential thermal (DTA)analysis, x-ray diffraction (XRD) and infrared rays (IR). The results showed that the powder grew very slow at low annealing temperature (<500℃ , while the powder grew very fast at the annealing temperature higher than 500℃. With the transformation of crystal style , the optics-characteristics of the powders have remarkable variation .The IR absorb side of the nanocrystalline TiO_2 powders both shift to lower frequencies and higher frequencies, and with the grain-size become small, the UV-VIS absorb side shift to lower frequencies, that show the quantum size effect. Using Ag~+ and Cu~(2+) doping; the photocatalysis respond spectrum range of the sample widen to solar wave band; and the photocatalytic activity also were enhanced. The photocatalytic mechanism of TiO_2 also were studied.TiO_2 based heterogeneous has potential to degrade environment pollutants by solar energy, degrade dry decolorization, and oil film in water.