Synthesis Of Vanadium Oxide Nanotubes Research Articles

Synthesis of vanadium oxide nanotubes via an ultrasonic method

Vanadium oxide nanotubes were synthesized using V2O5 powder as the precursor and hexadecylamine as the structure-directing template using a sol-gel reaction method followed by a one-step hydrothermal treatment. The effect of ultrasonics on the formation of nanotubes is reported. The structure and morphology of the nanotubes were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The inner and outer diameters of the nanotubes varied from 20 to 40 nm and 80 to 100 nm, respectively. The nanotubes measured several micrometers in length.

Effects of synthetic conditions on the structure and morphology of open-ended vanadium oxide nanotubes and study of their growth mechanism

Vanadium oxide nanotubes (VOx-NTs) have been synthesized by using n-butylamine as structure-directing template and V2O5 as precursor under hydrothermal conditions. XRD, FTIR, SEM, TEM, BET and TG-DTA characterizations have been performed to both optimize the synthetic conditions and understand the growth mechanism of VOx-NTs. The results showed that open-ended VOx-NTs were obtained under the optimized conditions (hydrothermal temperature: 150–160°C, hydrothermal time: 5–7 d, the molar ratio of V2O5 to n-butylamine is 1:1) with diameters ranging from about 30 to 100 nm and several micrometers in length. The BET surface area and the desorption cumulative pore volume of pores of the as-synthesized sample were about 27.4609 m2/g and 0.191087 cm3/g, respectively. The result presents that the synthesis of VOx-NTs is controlled by the “rolling” mechanism and temperature is primary driving force for rolling.

Hydrothermal Synthesis of Vanadium Oxide Nanotubes from Oxide Precursors

Vanadium oxide nanotubes were synthesized as the main product by a direct hydrothermal treatment of oxide precursors and long chain amines as structure-directing templates. The morphology and structure of nanotubes was characterized by powder X-ray diffraction, electron microscopy, and thermal analysis. Nanotubes of high aspect ratio with layered structures were found to grow together in the form of bundles. The paper also discusses the chemistry issues involved in synthesizing nanostructured vanadium oxides.

Hydrothermal synthesis of vanadium oxide nanotubes by a facile route

Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V 2O 5· nH 2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VO x -NTs which have a layered structure. TG-DTA study indicates that V 5+ cations in nanotubes are partially reduced to V 4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VO x nanotubes from lamellar structure because of the presence of V 4+ species.

A one-step hydrothermal way for the synthesis of vanadium oxide nanotubes containing the phenylpropylamine as template obtained via non-alkoxide route

Vanadium oxide nanotubes (VO x -NTs) with high crystallinity were synthesized by using the crystalline V 2O 5 as precursor for the first time with 3-phenylpropylamine as structure-directing template via one-step hydrothermal way. Structure and morphology of the nanotubes were investigated by Scanning Electron Microscopy, Transmission Electron Microscopy, X-ray powder diffraction, Thermal analysis and Infrared. The inner and the outer of the obtained nanotubes vary respectively between 15 to 25 nm and 70 to 100 nm with a length up to 4 μm.

Redox behavior of nanohybrid material with defined morphology: Vanadium oxide nanotubes intercalated with polyaniline

Vanadium oxide/polyaniline nanotubes were produced by cationic exchange between hexadecylamine and polyaniline after the synthesis of vanadium oxide nanotubes by sol–gel method followed by hydrothermal treatment. The local structure of this hybrid material was studied by high-resolution transmission electron microscopy, infrared and Raman spectroscopy and small angle X-ray diffraction technique. The results show that polyaniline is intercalated in the interlamellar space of the vanadium oxide nanotube forming a hybrid material with defined morphology. Electrochemical impedance spectroscopy experiments have shown that the apparent diffusion coefficient for nanotubes with template was approximately 1 × 10 −9 cm 2 s −1. Nanotubes with polyaniline presented an apparent diffusion coefficient at least one order in magnitude higher than the parent material “with template”, comparable with other vanadium oxide described in the literature, revealing a promising material for utilization as cathode for ion-Li batteries.

Synthesis of vanadium oxide nanotubes from V2O5 sols

Vanadium oxide nanotubes (VO x -NTs) were prepared by using V 2 O 5 sols as precursor for the first time with hexadecylamine (HDA) as structure-directing template via a modified sol–gel method followed by hydrothermal treatment. Structure and morphology of the nanotubes were investigated by XRD, SEM, HRTEM, TGA, FT-IR and XPS. The obtained nanotubes were found having outer diameters from 30 to 100 nm and inner diameters from 10 to 30 nm with length up to several micrometers. It is also confirmed that water molecules enter vanadium oxide layers together with structure-directing template and the low valence vanadium occurs in the VO x -NTs.

Synthesis of vanadium oxide nanotubes from V 2O 5 sols

Vanadium oxide nanotubes (VO x -NTs) were prepared by using V 2O 5 sols as precursor for the first time with hexadecylamine (HDA) as structure-directing template via a modified sol–gel method followed by hydrothermal treatment. Structure and morphology of the nanotubes were investigated by XRD, SEM, HRTEM, TGA, FT-IR and XPS. The obtained nanotubes were found having outer diameters from 30 to 100 nm and inner diameters from 10 to 30 nm with length up to several micrometers. It is also confirmed that water molecules enter vanadium oxide layers together with structure-directing template and the low valence vanadium occurs in the VO x -NTs.

Vanadium Oxide Nanotubes: New Synthesis Route and Mechanism of Formation.

ABSTRACTThe synthesis of vanadium oxide nanotubes containing phosphorus (VPOx-NT) is described. A mixture of V2O5.nH2O gels, phosphoric acid and hexadecylamine was heated under hydrothermal conditions at 180°C for 7 days. The VPOx nanotubes were characterized by X-ray diffraction, scanning and transmission electron microscopy, 51V and 31P solid state NMR. In-situ experiments were performed in order to get a better understanding of the mechanism of these nanotubes formation.

Self-assembling synthesis of vanadium oxide nanotubes and simple determination of the content of V(IV)

High-yielding low-cost vanadium oxide nanotubes were prepared by the hydrothermal self-assembling process from vanadium pentoxide and organic molecules as structure-directing templates. Moreover, a new method was discovered for determining the content of V (IV) in vanadium oxide nanotubes by thermogravimetric analysis (TGA). This method is simple, precise and feasible and can be extended to determine the content of low oxidation state in the other transition metal oxide nanomaterials.

Cost-saving synthesis of vanadium oxide nanotubes

The synthesis of vanadium oxide nanotubes has been achieved by using V 2O 5 as vanadium oxide precursor. Due to its low cost, high yield and ease of handling, the synthesis starting from V 2O 5 provides an advantageous access to large quantity of the tubular vanadium oxide nanotubes.

Hydrothermal synthesis of vanadium oxide nanotubes from V 2O 5 gels

Vanadium oxide nanotubes (VO x -NT) have been synthesized in high yield by adding hexadecylamine to V 2O 5· nH 2O gels, followed by a hydrothermal treatment (150–180 °C, 2–7 days). Scanning electron microscopy (SEM) and X-ray diffraction analysis have been performed to optimize the temperature and reaction time required for formation of VO x -NT and the morphology of the nanotubes investigated by transmission electron microscopy (TEM).

The First Vanadium Oxide Nanotubes Containing an Aromatic Amine as Template

A new vanadate has been prepared in high yield by reacting vanadium(V) triisopropoxide and 3-phenylpropylamine in solution, followed by hydrolysis and hydrothermal treatment of the intermediate product. For the first time, an aromatic amine has successfully been applied as structure-directing template for the synthesis of vanadium oxide nanotubes. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate the tubular morphology of the phenylpropylamine vanadium oxide nanotubes obtained. The size and structure are similar to that of vanadium oxide nanotubes formed with aliphatic amines. The tube walls comprise layers of vanadium oxide with the organic template intercalated in between. The interlayer distance is ca. 2.1 nm, and the structure of the VOx layers can be described by a square lattice with a≈0.61 nm. Furthermore, the TEM investigation has revealed the presence of many defects in the wall structure.

The First Vanadium Oxide Nanotubes Containing an Aromatic Amine as Template

A new vanadate has been prepared in high yield by reacting vanadium(V) triisopropoxide and 3-phenylpropylamine in solution, followed by hydrolysis and hydrothermal treatment of the intermediate product. For the first time, an aromatic amine has successfully been applied as structure-directing template for the synthesis of vanadium oxide nanotubes. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images demonstrate the tubular morphology of the phenylpropylamine vanadium oxide nanotubes obtained. The size and structure are similar to that of vanadium oxide nanotubes formed with aliphatic amines. The tube walls comprise layers of vanadium oxide with the organic template intercalated in between. The interlayer distance is ca. 2.1 nm, and the structure of the VOx layers can be described by a square lattice with a≈0.61 nm. Furthermore, the TEM investigation has revealed the presence of many defects in the wall structure.

Low-Cost Synthesis of Vanadium Oxide Nanotubes via Two Novel Non-Alkoxide Routes

The synthesis of vanadium oxide nanotubes (VOx-NTs) containing primary monoamines with long alkyl chains has been achieved by two new approaches, using either VOCl3 or V2O5 as vanadium oxide precursor. The hydrolysis of amine complexes of VOCl3 involves a ligand-assisted templating mechanism as well as the intercalation of amines in layered V2O5. Both procedures followed by a hydrothermal treatment lead to VOx-NTs as the main product. The structure and morphology of the tubes obtained have been investigated and are discussed in terms of comparison with those obtained by the previously reported alkoxide route. Due to its low cost and ease of handling, the synthesis starting from V2O5 in particular provides an advantageous access to large quantities of the novel tubular nanomaterial.