Influence of Na+ content on the structure and morphology of TiO2 nanoparticles prepared by hydrothermal transformation of alkaline titanate nanotubes

The objective of this study is to investigate the role of Na+ content in the morphology evolution of TiO2 nanoparticles prepared by hydrothermal approach. Various TiO2 morphology from 0-dimensional (0D) nanoparticles to 1-dimensional (1D) nanorods were synthesised by hydrothermally treating the alkali titanate nanotubes with different Na+ content. The XRD patterns show the phase transformation and crystallographic nature of alkali titanate nanotubes are strongly dependent on the Na+ content, the cation exchange of Na+ by H+ ion exchange affects the crystallinity of the tubes and causes disorder of the interlayers of nanotubes. The SEM and TEM images confirm that Na+ rich titanate nanotubes were thermally stable. Moreover, BET measurements revealed that the Na+ content plays an important role on the specific surface area of formed TiO2 nanoparticles. The photocatalytic activity of the TiO2 nanoparticles was characterised via the decomposition rate of an aqueous solution of methyl orange (MO) under UV light irradiation. The TiO2 nanoparticles prepared by hydrothermally treating the alkali titanate nanotubes with no Na+ content has a surface area of 55.1 m(2)/g with nearly 100% photodecomposition of MO in 20 min.