Novel approach for the synthesis of rutile titania nanotubes at very low temperature

A novel method is presented to synthesize crystalline rutile titania nanotube at comparatively lower temperature than reported previously. A conversion from commercial titania nanoparticles to nanotubes was achieved by hydrothermal method with 10M NaOH, at 70 °C for 48 h. The mixture of titania and NaOH was sonicated for at different times before loading into a hydrothermal reactor. With increasing sonication time a phase transition from anatase to rutile was observed with structural transition from spherical particles to nanotubes. A gradual reduction in x-ray diffraction peak intensities of anatase with a new peak corresponding to the layered titanate is observed. With increasing sonication time, the observed Raman bands are significantly different from that of the commercial TiO₂ powder, indicating the changes in the phase with treatment time. Specific surface area is found to increase with the sonication times. The mechanical energy from sonication appears to be helpful in increased dispersion of the nanoparticles in NaOH solution aiding the phase transition from anatase to rutile.