Two-step template-free route for synthesis of TiO₂ hollow spheres

The TiO₂ hollow microspheres were prepared by microwave-assisted solvothermal treatment without template. The morphology and the phase of TiO₂ hollow microspheres were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and BET surface areas. The results show that the particles have hollow structures and the shell was covered by nanocrystals and have higher specific surface area. The possible formation mechanism of hollow TiO₂ spherical structures has simply been proposed. The activity was evaluated by the photocatalytic degradation of methyl orange (MO). The results show that the particles having specific surface area show higher photocatalytic activity. It can be attribute to the doped F atoms and the creation of oxygen vacancies.