Implications of Precursor Chemistry on the Alkaline Hydrothermal Synthesis of Titania/Titanate Nanostructures

Abstract

A systematic study of four parameters within the alkaline hydrothermal treatment of three commercial titania powdersanatase, rutile, and Degussa P25was made. These powders were treated with 5, 7.5, 9, and 10 M NaOH between 100 and 220 °C for 20 h. The effects of alkaline concentration, hydrothermal temperature, and precursor phase and crystallite size on the resultant nanostructure formation have been studied through X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and nitrogen adsorption. Through the correlation of these data, morphological phase diagrams were constructed for each commercial powder. Interpretation of the resultant morphological phase diagrams indicates that alkaline concentration and hydrothermal temperature affect nanostructure formation independently, where nanoribbon formation is significantly influenced by temperature for initial formation. The phase and crystallite size of the precursor also significantly influenced nanostructure formation, with rutile displaying a slower rate of precursor consumption compared with anatase. Small crystallite titania precursors formed nanostructures at reduced hydrothermal temperatures.

Synthesis, characterization and optical spectroscopy of Eu3+ doped titanate nanotubes

“…The relative intensities and the widths of the bands are quite similar to those observed for titanate nanotubes, with pseudolepidrocite layer structure, reported by other authors [26,27]. In particular, the strong and broad band peaked at 276 cm À 1 can be assumed as a key indicator of the formation of the nanotube phase, as pointed out by Morgan et al [28]. In our case, an additional, quite narrow, band peaked at 144 cm À 1 is attributed to the E g vibrational mode of anatase TiO 2 [29], present as a segregated phase.…”

Osteogenic activity of titanium surfaces with nanonetwork structures

“…30 The nanotopography of nanonetwork structures with TNS nanofeatures is affected by temperature, treatment time, and alkaline concentration. 20,[31][32][33] The objectives of the present study were twofold: first, we aimed to investigate the changes in TNS, such as roughness, wettability, and surface structure induced by various alkaline concentrations (2.5, 5.0, 7.5, 10.0, and 12.5 M), and second, we aimed to evaluate the influence of such modified nanonetwork structures with TNS nanofeatures, with different alkaline concentrations, on the osteogenic differentiation of rat BMMSCs. To the best of our knowledge, this is the first study to evaluate the effects of titanium surfaces with nanonetwork structures formed by various alkali concentrations at room temperature on osteogenic differentiation.…”

Metal Oxide Semiconductors and their Nanocomposites Application Towards Photovoltaic and Photocatalytic

“…The Raman band at ~638.1 cm -1 has been assigned to the symmetric Ti-O vibration from the Ag symmetric modes of the TiO 6 octahedra [39], whereas those at ~396 and ~514.4 cm -1 refer to the splitting of the degenerate mode of the TiO 6 octahedra in the TiO 2 nanostructures [40]. Importantly, the appearance of the strong and broad band peak at ~396 cm -1 is the main peak, which indicates the formation of the TiO 2 nanostructures [41]. Compared to the distorted hexagonal TiO 2 NRs, the high intensity Raman bands of highly ordered tetragonal TiO 2 NRs might ascribe to their better optical and crystalline properties.…”