Hydrothermal synthesis of titanate nanowire arrays

A simple templateless synthesis strategy for titanate nanowire arrays was developed by employing hydrothermal reactions. Hydrothermal treatment of metallic titanium powder with H2O2 in a 10 M NaOH solution produced a new sodium titanate compound, Na2Ti6O13·xH2O (x ∼ 4.2), as arrays of nanowires of lengths up to 1 mm. The nanowires were characterized by using XRD, SEM, TGA, and TEM. The nanowires have exceptionally large aspect ratios of 5000 or higher, and they can form arrays over a large area of 2 × 3 cm2. Investigations on the reaction products in varied conditions indicate that the array formation requires simultaneously controlled formation and crystal growth rates of the Na2Ti6O13·xH2O phase.