Papers by Keyword: Titanate Nanotube

Abstract: The visible-light photocatalytic activity of titanate nanotubes (TiNTs) sensitized by 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetraphenylporphyrin manganese (MnTPP), 5,10,15,20-tetraphenylporphyrin nickel (NiTPP) and 5,10,15,20-tetraphenylporphyrin zinc (ZnTPP), respectively, was investigated by the photocatalytic degradation of methyl orange (MO) as a probe reaction. The results showed that the central ions of porphyrins had an important influence on the photocatalytic activity of the samples. The activity was in the order of TiNTs-ZnTPP > TiNTs-TPP > TiNTs-NiTPP > TiNTs-MnTPP. Combined the result of absorption spectra with that of fluorescence spectra, it was demonstrated that various visible-light absorption and photoelectron transfer caused by the central ions of porphyrins were the decisive factor for the visible-light photocatalytic activity of the sensitized TiNTs.

Abstract: Titanate nanotubes (TNTs) were prepared by treatment of anatase-TiO2 nanoparticles in mild hydrothermal conditions. TNTs were characterized by XRD, TEM, FT-IR and BET specific surface area technique. It was found that nanotubes might be NaxH2-xTi3O7 and were formed during the hydrothermal process, rather than during the treatment process with acid solution. The formation mechanism of TNTs can be explained as 3D→2D→1D. After hydrothermally reacting at 130°C for 48h, the as-prepared products exhibit hollow nanotubes with open ends, more than 100 nm in length, 10 nm in outer diameters, large BET surface area and pore volume, which may lead to potential photocatalysis and absorption application.

Abstract: Titanate nanotubes were successfully synthesized by means of an alkaline hydrothermal method and further appropriate post-treatments. The effect of different washing treatments on the formation of titanate nanotubes were systematically studied in this paper. It was found that the washing treatments play an important role in the formation of nanotubes. Treating with 0.1M NaCl aqueous solution mainly resulted in titanate nanosheets while treating with deionized water or 0.1M HCl aqueous solution (1 time, PH>7) can obtain highly crystallized titanate nanotubes. Furthermore, if the PH values of solutions after acid washing processes were below 7, trace of nanotubes can be found but almost all of them were damaged. On the basis of all the present experimental results, we can conclude that titanate nanotubes can be prepared as long as the driving force induced by the imbalance of sodium ion (Na+) concentration on two different sides of nanosheets was appropriate, and meanwhile they were instable in acidic solutions.

Abstract: In the present work, a novel titanate (H2Ti5O11•3H2O) nanotubes are synthesized by a simple hydrothermal method, and their thermal stability such as the phase transformations and microstructures change are also studied. The as-grown samples are heated in the air at 300-800 °C. The titanate nanotubes will be completely destroyed when the temperatures are above 600 °C, which show that the present titanate nanotubes possess good thermal stabilization. The experiment results reveal that the phase transformations and microstructure changes of present titanate nanotubes follow the process from titanate nanotubes to anatase and rutile TiO2 nanobelts, the Na2Ti6O13 nanwires are formed over 700 °C.

Abstract: Titanate nanotubes have been directly prepared by hydrothermally treating P25 powders in NaOH aqueous solution. Effect of calcination temperature on crystal phase, morphologies and specific surface area of the as-synthesized nanotubes has been investigated in detail. The Na2Ti3O7 tubular structure could be kept well even after calcination at 600 °C and began to transform to Na2Ti6O13 nanorods at around 645 °C. The specific surface area of the as-synthesized nanotubes was 200.6 m2/g and reached to the maximum of 347.9 m2/g after calcination at 300 °C and then decreased sharply with the further increase of the calcination temperature.

Abstract: Nanomaterials are of great importance for their versatile applications in gas sensors, solar cells and photocatalysis due to their unique optical, electrical and catalytic properties. Titania derived nanotubular and nanospherical particles with a titanate structure were synthesized using a hydrothermal procedure in the presence of very concentrated solutions of KOH and NaOH respectively. Both nanostructures were found to exhibit relatively large specific surface areas, i.e. 280 and 303 m2/g for materials treated in NaOH and KOH respectively. The morphological and structural properties were characterised by TEM, SEM, Raman spectroscopy and XRD.

Abstract: The TiO2 sol was prepared hydrothermally in an autoclave from aqueous TiOCl2 solutions as starting precursor. Hollow fibers were obtained when sol-gel derived TiO2 sol was treated chemically with NaOH solution and subsequently heated in autoclave under various conditions. A systematic analysis of the influence of different NaOH concentrations on the formation of nanotubes has been carried out using XRD and SEM. The phase structure of the synthesized material was determined by transmission electron microscopy and found that these materials are, infact, hollow fibers widely known as nanotubes. From the TEM images, the outer and inner diameters of the tubes were measured ca. 8 and about 4 nm, respectively, with several hundred nanometers in length.

Abstract: Antibacterial titanate nanotubes were synthesized by alkali digesting of metatitanic acid via hydrothermal route, following by cation-exchanged and immobilized with Ag+, Zn2+ and Cu2+. The conditions for nanotube synthesis and ion exchange were investigated; the microstructures of as-synthesized nanotubes were characterized by XRD, SEM, XPS and DTA/TG. The antibacterial performance of cation-doped titanate nanotubes was tested and evaluated by Escherichia Coli. and staphylococcus aureus.

Abstract: Slim titanate naotubes was prepared from industrial coarse TiO2 powder by simple sonochemical-hydrothermal processing. The influences of ultrasonic irradiation on TiO2 precursors were investigated. The morphology and crystal structure of the products were characterized by TEM and X-ray diffraction, respectively. The typical products are long nanotubes around 8-10nm in out diameter. Both anatase and rutile TiO2 precursors can be transferred into titanate nanotubes in this sonochemical & hydrothermal processing.