Facile synthesis of anatase titania microspheres by a novel pyrolysis method and their photocatalytic properties

摘要

Anatase titanium dioxide (TiO_2) microspheres with high photocatalytic activity were prepared by a novel pyrolysis method using titanium sulfate powders as the precursor. The photocatalytic activity of the as-obtained anatase TiO_2 microspheres was evaluated by degrading rhodamine B (RhB, 20 mg/L) and 4-nitrophenol (4-NP, 10 mg/L) under UV-light irradiation at room temperature. A possible mechanism for the formation of the TiO_2 microspheres was proposed. The effects of calcination temperature and time on the morphologies and photocatalytic activities of the TiO_2 microspheres were studied. It was found that the anatase TiO_2 microspheres can be obtained above 600 ℃. The nucleation of primary TiO_2 particles stemmed from the rapid pyrolysis of titanium sulfate powders, followed by the aggregation and recrystallization, resulting in the formation of the anatase TiO_2 microspheres. With increasing the calcination temperature from 600 to 900 ℃, the crystallinity and pore size of the TiO_2 microspheres increased and their specific surface areas decreased. The experimental results indicate that the crystallinity and specific surface area of the TiO_2 microspheres have significant effects on their photocatalytic activities. The as-synthesized TiO_2 microspheres obtained at 700 ℃ for 6 h exhibited the highest photocatalytic activity and good stability.