Synthesis and characterisation of TiO₂-derived nanotubes

TiO2-based nanotubes were synthesised via hydrothermal and reflux methods in a 10 N NaOH solution at 403 K under stirring for 20–72 h from nano TiO2 and industrial TiO2 powders. The results show that the yield of nanotube formed through the hydrothermal method is higher than that of the reflux method. The samples were characterised by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images and X-ray diffractometer (XRD) patterns to investigate the phase of the nanotubes. The results from XRD patterns show that nanotubes consist of a titanate structure with general formula Na x H2− x Ti3O7, where 0 ≤ x ≤ 2, depending on degree of proton exchanged after acid washing. TEM images show the inner and outer diameters to be about 3 and 9 nm, respectively, for nanotubes. Also the SEM images show that the lengths of nanotubes are about several 10 µm.