Papers by Keyword: Nanotube

Abstract: Nanotubes, fabricated by mechanical bending of thin films, have been widely used in numerous fields. For a bilayer nanofilm, it could bend itself driven by effects of adsorption and ambient temperature. Therefore, in this work, we simulate the phenomenon of bilayer AuSi nanofilm bending into nanotube with the effects of surface stress induced by vdW interaction between adsorbed O or Hg atoms and atoms on Au surface and ambient temperature change by finite element emulation. The curves of nanotube calculated by finite element software accord with theoretical prediction results very well, that demonstrate our theoretical prediction formula has a great feasibility and efficiency in practical application.

Abstract: A new type S-F-codoped TiO2 nanotubes electrode was fabricated by forming nanotube- like TiO2 film on a Ti sheet in an anodic oxidation process. The micro-morphology and elemental composition of it were analyzed by FE-SEM and XPS, respectively. The average diameters of these nanotubes ranged from 100 to 200 nm. The evidences from XPS indicated that S and F atoms had been doped into TiO2 nanotube. And the experiments of photoelectrocatalytic degradation of Acid Orange II (AO7) with this electrode as working electrode were carried out.

Abstract: The use of nanosized semiconductor particles in various forms for the photocatalytic degradation of pollutants has been discussed. The aim of this review is to provide a critical analysis of various reports on the degradation of pollutants by various semiconductor nanomaterials. It has been shown that self-organized one-dimensional nanotube matrix creates a better opportunity to remove pollutants more efficiently than the randomly oriented nanoparticles. The use of metal doping and mixed semiconductor systems has also been analyzed. Although large improvements in the present technology are required, the review points to focus on the advantages of nanomaterials compared to bulk materials in efficient purification of water.

Abstract: TiO2 nanotube arrays were prepared using template-based liquid phase deposition method. Their morphologies and structures were investigated by scanning electron micro¬scopy, transmission electron microscopy and X-ray diffraction. The photocatalytic properties of the samples were evaluated with the degradation of methylene blue under UV irradiation. It was found that the TiO2 nanotube arrays annealed at 900 °C showed the highest photocatalytic activity.

Abstract: TiO₂ nanostructures with a pure anatase phase were successfully synthesized using hydrothermal treatment of P25-TiO₂ nanoparticles. These nanostructures were characterized using transmission electron microscopy (TEM) and x-ray powder diffraction measurements. The dependences of reaction temperature and calcination temperature on titanate-anatase phase transformation and the morphology of TiO₂ nanostructures were also discussed. The results demonstrated that phase composition and particle morphology can be controlled by both the reaction and calcination temperatures.

Abstract: The single walled armchair (3,3) (BN)xCy nanotubes with different ratios of B, C and N atoms were studied with density functional theory of B3LYP/3-21G(d) combined with the periodic boundary conditions in simulating the ultra long tube model. Different types of twelve models were examined and the diameter, energy, energy gaps and the band structures were obtained. The energy gaps were within 0.203eV to 2.620eV showing semiconductor conductivity. Results show that the energy gap and the band structure depend on both the atom ratio and arrangement.

Abstract: Carbon nanotubes with polymers offers great advantages in improving material for both mechanical and electrical nanostructures. Design and fabrication have to consider that a local change in each compound accounts to the total change of physical properties in nanocomposite materials. This paper presents two parts of study. A model of strain nanosensor has been developed by using the polyvinylidne fluoride and trifluoroethylene P(VDF-TrFE) copolymer and carbon nanotubes in sandwich nanostructure [P(VDF-TrFE)/SWCNTs/ P(VDF-TrFE)] as a new application in nanotechnology domain. The experimental strain sensing was about 10^-4. On the other hand, reliability-based optimization is assessed for an efficient tool to consider this nanosensors nanodevice. We put emphasis on the combination of physical modeling and reliability based design optimization of nanomaterials. After investigation, we could make suggestions such as how to improve the reliability of nanodevices and nanosystems, and how to reduce cost and economic rates.

Abstract: Horseradish peroxidase (HRP) was successfully immobilized on vertically oriented TiO₂ nanotube arrays (NTAs), which was prepared by seeded-growth mechanism. The nanotubular structure of TiO₂ was characterized by scanning electron microscope (SEM). After encapsulated HRP on TiO₂ nanotube arrays, the direct electron transfer of HRP was observed.

Abstract: The objective is to demonstrate that physical properties of multifunctional material systems can be tailored for specific applications by controlling different types of nanotubes, their concentration and degree of alignment. The properties of structured polymers can be enhanced by combining nano tubes with desired properties to form a nano polymer. These may have the potential to provide structural integrity as well as sensing and/or actuation capabilities. By proper selection of the polymer matrix to promote donor acception and/or dispersion interactions can improve adhesion at the interface between the nano- tubes and hence also the polymer matrix significantly. An effective sensor material that responds to strain, stress, pressure, and temperature can be yielded by using very small loadings of single wall nanotubes in a polyimide matrix. These materials also exhibit significant actuation in response to applied electric fields. Alternative thermodynamic routes involve enhancing polymer/SWCNT interactions via amphiphilic surfactants, hydrophobic interaction with nanotubes, physical wrapping with conjugated polymers which exhibit enhanced dispersion interactions by adopting a π-stacked geometry , donor-acceptor interactions via charge transfer , Zwitterion complex formation , and non-specific interactions using DNA or peptide sequence.

Abstract: Mesostructured nickel phosphate was synthesized with urea as alkali by sol-gel method. The obtained material nominated as NiPO-3 was characterized by means of XRD, ICP, FT-IR, TEM, and N₂ adsorption. In contrast to mesoporous nickel phosphate NiPO-1 and NiPO-2 we reported before, NiPO-3 exhibits relatively longer nanotubes reached up to 400~600 nm. N2 adsorption shows that NiPO-3 possesses high BET surface area (345.8 m²g^-1) and pore volume (0.46 cm³g^-1). The catalytic performance of NiPO-3 showed that the total selectivity of epoxycyclohexane and hexadienol was as high as 83.38%.