Synthesis and characterisation of nanotubular titanates and titania

Nanotubular titanates and titania, with an external diameter of around 8 nm and a wall thickness of about 1 nm, were synthesised by hydrothermal processing. Their morphological and structural properties were characterised by TEM and XRD, respectively, and their thermal stability was evaluated. The formation of nanotubular products was due to hydrothermal treatment, rather than washing process, but the pH values of washing solutions could determine the composition of the products. Sodium titanates, hydrogen titanates and titania nanotubes could be synthesised, respectively, via changing the pH value of washing solutions and the heat-treatment temperature. The nanotubes remained in their shape at 400 °C, fused together at 600 °C, and completely lost their nanotubular shape to give aggregated anatase nano-particles at 800 °C.