Systematically synthesized one-dimensional (1D) nanomaterials - nanotubes (NTs), nanofibers (NFs) and nanoribbons (NRs) - based on TiO₂ were characterized using thermal analysis, Energy-dispersive X-ray Spectroscopy(EDS), X-ray Photoelectron Spectroscopy (XPS) analysis, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. ₂...[ Read more ]

Systematically synthesized one-dimensional (1D) nanomaterials - nanotubes (NTs), nanofibers (NFs) and nanoribbons (NRs) - based on TiO₂ were characterized using thermal analysis, Energy-dispersive X-ray Spectroscopy(EDS), X-ray Photoelectron Spectroscopy (XPS) analysis, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques.

Effects of different starting materials, temperature and other reaction parameters on the formation of various nanostructures were examined. Crystalline TiO₂ precursor treated in alkali solution results in NTs and amorphous precursor produces NFs at lower temperature (100-180°C) while twinned NRs are generally produced at higher temperature (>180°C).

EDS, XRD and electron diffraction (ED) results suggested the coexistence of anatase and an orthorhombic titanate A_xTi_2-x/4 Π_x/4O₄ (A: H⁺ or Na⁺, x≈ 0.7, Π: vacancy) phase in all three 1D nanoproducts. High-resolution TEM evidences and image simulation confirmed that the formation of TiO₂-based nanostructures was driven by 45° anatase-titanate quasi-twins, which formed the building blocks of NTs, NFs and NRs. The structure of NR was investigated relying on the series of ED patterns obtained by tilting the NR along its long-axis. The ED pattern series was consistent with the one predicted by the proposed model.

By electron irradiation in TEM, a cubic TiO phase was discovered in NTs and NRs. XPS analysis suggests the existence of reduced state of Titanium in the sample while high temperature and high vacuum environment of TEM preserves the Ti-rich phase leading to the formation of TiO structure.