Preparation and photocatalytic properties of core-shell nano-TiO2 @ α-Al2O3 microspheres

Core-shell nano-TiO2@a-Al2O3 microspheres of 5-20 μm were prepared by the heterogeneous precipitation method combined with the hydro-thermal and calcination process using α-Al2O3 microspheres as substrate. Their morphologies, microstructure and crystalline phase were characterized by SEM and XRD respectively. The photocatalytic activity was evaluated by degradation of methyl orange. The as-prepared 10 wt.% nano-TiO2@α -Al2O3 microspheres possess α core-shell structure with a monolayer of nano-TiO2 particles less than 30 nm on the surface of α-Al2O3 microspheres. Their photocatalytic properties are largely influenced by the calcination temperature and the sample calcined at 800 degrees C for 2 h has the best photocatalytic activity. This high photocatalytic activity can be attributed to the synergetic effects of the unique structure of nano-TiO2 @α-Al2O3 microspheres, quantum size effect, composition of crystalline phase and crystallinity of nano-TiO2. These nano-TiO2@α-Al2O3 microspheres may be conveniently separable and useful in practical treatment of organic waste waters due to the large particle size and high photocatalytic properties.