关键词: TiO₂片晶, 水热制备, 微米级混晶, 光催化性能

Abstract: Controlling the size and morphology of TiO₂ within micron-size, could help to carry out the idea that TiO₂ photocatalyst can be easily recycled with remarkable photocatalystic property. Micron-size titanium dioxide(TiO₂) flaky crystal was synthesized by means of a simple template-free hydrothermal method using rutile TiO₂ as raw material. Then the morphology and crystalline structure of the obtained samples were characterized by using scanning electron microscope(SEM), X-ray diffraction(XRD) and N₂ adsorption / desorption methods. TiO₂ flaky crystal showed a length of 60—80 μm, width of about 30—60 μm and thickness of 4—9 μm. The XRD peaks attributed to H₂Ti₄O₉·H₂O after hydrothermal reaction, while turned to bi-phase TiO₂ by calcination. The BET surface areas and pore sizes are 68 m²·g^-1, 244 m²·g^-1 and 21.6 nm, 10.4 nm with or without calcined, respectively. The formation mechanism of TiO₂ flaky crystal was also speculated based on the experimental results. The photocatalytic performance of the calcined samples was tested in the degradation of the methyl orange(MO), under UV light irradiation. For comparison, Degussa P25 powder was used as a reference catalyst. The calcination temperature obviously influenced the UV light photocatalytic activity of the TiO₂ samples. In particular, the flake-like bi-phase TiO₂ obtained by calcination treatment at 450℃ exhibits the highest photodegradation efficiency of MO. Results indicated that exposing the solution of MO with the catalyst for 30 min, a decomposition degree 92.4% was obtained, and after 60 min the dye was almost totally decomposed. The TiO₂ flaky crystal presented here performed as practical photocatalysts for water purification, as it can be easily recycled in the shape of the large grain size.

Key words: TiO₂ flaky crystal, hydrothermal synthesis, micron-size mixed crystal, photocatalytic performance