Novel core-shell structured mesoporous titania microspheres: Preparation, characterization and excellent photocatalytic activity in phenol abatement

Thermally stable mesoporous core-shell structured nanocrystallite titanium dioxide (TiO2) microspheres were prepared by a novel hydro-alcohol thermal method. Anatase powders were synthesized under hydrothermal condition at 368 K from aqueous titania tetrachloride solution with the presence of urea and ammonium sulfate, then the samples were annealed at various temperatures before testing their photocatalytic activity. The morphology and microstructure characteristics of TiO2 microspheres series were characterized by means of the specific surface area (BET), transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential thermal analysis (DTA), photoluminescence spectra (PLS), X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD). The specific microsphere structures were maintained after a heat treatment at 973 K for 3 h, exhibiting a significant thermal stability. The photocatalytic activity was measured in a reactor with ultraviolet lamps. The catalysts show considerably high catalytic activity and recyclability during the photodegradation of phenol in aqueous suspension, the microsphere titania sample calcinated under 733 K for 3 h shows the best photocatalytic activity. The results obtained with this novel photocatalyst are compared with the behavior of the well-studied and widely used Degussa P25 TiO2 under the same conditions. (C) 2007 Elsevier B.V. All rights reserved.