Multistep structural transition of hydrogen trititanate nanotubes into TiO₂-B nanotubes: a comparison study between nanostructured and bulk materials

Abstract

H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO(2) followed by proton exchange were compared to their bulk H(2)Ti(3)O(7) counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H(2)Ti(3)O(7) nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H(2)Ti(3)O(7) converts into TiO(2)(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 degrees C through topotactic mechanisms with the intermediate formation of nanostructured H(2)Ti(6)O(13) and H(2)Ti(12)O(25), which are more condensed layered titanates eventually rearranging to TiO(2)(B). Our results suggest that the intermediate tunnel structure H(2)Ti(12)O(25) is the final layered intermediate phase, on which TiO(2)(B) nucleates and grows. The conversion of nanostructured TiO(2)(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

“…Determination of their pKa is typically done by titration [65], thermogravimetry or programmed adsorption/desorption (methylene blue [67], pyridine [68], CO 2 [69]). …”

The Effect of Ionic Charge on the Adsorption of Organic Dyes onto Titanate Nanotubes

“…[41] Titanate nanotubes decorated with dye molecules have potential application in dye sensitized solar cells. In typical cell manufacturing processes, the suspension of nanotubes is deposited on the surface of electro-conductive glass followed by calcination at 450 • C. Such high-temperature thermal treatments results in structural and morphological changes of nanotubes, [5,42] which may affect the affinity of dye molecules for the surface of the semiconductor.According to recent reports, [43] annealing of protonated titanate nanotubes (H-TiNT) at 400 • C results in a 34% decrease of their specific surface area, accompanied by loss of water molecules and transformation of titanates to monoclinic TiO 2 (B), [42] maintaining nanotubular morphology. Analysis of MB adsorption isotherm on the surface of annealed samples have revealed that calcination of protonated nanotubes in air at 400 • C for 24 h results in ∼30% decrease of the amount of MB molecules forming the monolayer on the surface of nanotubes (a s ) and 75% decrease of adsorption constant K L ( Table 1).…”

Electrochemical kinetics of nanostructure LiFePO 4 /graphitic carbon electrodes

“…However, most of these pseudocapacitive materials operate in aqueous electrolytes, thus limiting their practical interest for high-energy supercapacitor applications. V 2 O 5 [10], H 2 Ti 3 O 7 [11,12] and TiO 2 (B) [13,14] were among the first materials showing pseudocapacitive behavior in Li + containing nonaqueous electrolytes. Although high capacity (200 mAh g −1 ) was obtained, cyclability and power performance are still a concern [15].…”