Synthesis of bundle-like structure of titania nanotubes

Bundle-like structure of titania nanotubes has been synthesized via the reaction of anatase titania nanoparticles and NaOH aqueous solution at higher treatment temperatures (higher than 190 °C) after calcination at 500 °C for 1 h. The bundle-like structure of titania nanotubes is characterized by transmission electron microscope (TEM) and field-emission scanning electron microscope (FE-SEM). The tubular structures of titania with diameters of 5-15 nm are confirmed by TEM. The effects of treatment temperatures on the morphologies of titania nanostructures are investigated. As SEM images show, when the treatment temperature is 170 °C, randomly oriented structure of titania nanotubes coexisting with titania nanobelts are obtained. However, bundle-like structure of titania nanotubes with lengths of several micrometers are fabricated at high treatment temperatures (higher than 190 °C). X-ray diffraction (XRD) pattern shows that anatase phase titania nanotubes are synthesized after calcination at 500 °C for 1 h.