Titania Nanotubes Prepared by Chemical Processing

We report a new method for the synthesis of titanium oxide (TiO2) nanotubes. When anatase‐phase‐ or rutile‐phase‐containing TiO2 was treated with an aqueous solution of 5–10 M NaOH for 20 h at 110 °C and then with HCl aqueous solution and distilled water, needle‐shaped TiO2 products were obtained (diameter ≈ 8 nm, length ≈ 100 nm). The needle‐shaped products are nanotubes with inner diameters of approximately 5 nm and outer diameters of approximately 8 nm. The formation mechanism of titania nanotubes is discussed in terms of the detailed observation of the products by transmission electron microscopy: the crystalline raw material is first converted to an amorphous product through alkali treatment, and subsequently, titania nanotubes are formed after treatment with distilled water and HCl aqueous solution. The formation mechanism of titania nanotubes prepared by a chemical processing method is examined. Scanning and transmission electron microscopies are used to observe the material as it is converted from rutile powder through treatment with alkali, distilled water, and HCl to titania nanotubes. The Figure is a scanning electron microscopy image of the final material.