Solvent-controlled synthesis and photocatalytic activity of hollow TiO2 microspheres prepared by the solvothermal method

Hollow titanium dioxide (TiO2) microspheres are important metal oxide nanomaterials that can be synthesized via facile template-free solvothermal method based on the Ostwald ripening process. The properties of the organic solvents imposed significant effects on the microstructures and properties of the final products. However, the effects of solvent type were less understood during the formation of hollow TiO2 microspheres. So in this work, four organic solvents, namely methanol, isopropanol, ethanediol and actone, were selected to mix with ethanol as the mixed solvents for the solvothermal synthesis of hollow TiO2 microspheres based on the Ostwald ripening process. Special attentions were paid to the morphology and crystallinity of TiO2 nanostructures. A series of characterization results showed that acetone had significant effects on the construction of hollow structures due to its moderate polarity, low boiling point and viscosity. This method demonstrated the great controllability of the hollow structures. The TiO2 nanostructures with hollow structures exhibited an enhanced performance for degradation of Rhodamine B. When irradiated with ultraviolet light for 120 min, the residual rates of RhB solutions were almost zero.