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Single fibres of pyro-electrospinned PVDF-HFP/MWCNT unveal high electrical conductivity
摘要： Formation of single fibres of polymer nanocomposite PVDF-HFP containing MWCNT by Pyro-EHD electrospinning is reported for the first time. Pyro-EHD gives the chance to drawing fibres directly from a viscous polymeric solution containing MWCNT, with respect to classical electrospinning in which highly viscous materials have strong limitation due to the clogging effect. This method allows achieving an electrical conductivity of the fibres considerably higher with respect to the bulk state. The improvement of the electrical conductivity is of one order of magnitude and the electrical percolation threshold is reduced from 2.5 to 0.3 wt%. We also show that the MWCNT are highly oriented in the longitudinal direction of the fibres, producing the improvement in the electrical properties of the composite.
关键词： carbon nanotubes,electrical percolation,PVDF-HFP
更新于2025-09-10 09:29:36
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Chemical Sensing Applications of Carbon Nanotube-Deposited Optical Fibre Sensors
摘要： Carbon nanotubes are unique one-dimensional materials which can experience a modi?cation in their optical properties as the chemical composition of their ambient environment varies. One of the ways to interrogate these variations in optical properties is through the use of optical ?bres. As such, their integration with optical ?bre technology would potentially allow for the development of devices for various chemical sensing applications.
关键词： carbon nanotubes,chemical sensing,optical ?bre sensors
更新于2025-09-10 09:29:36
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Nano-scale wave dispersion beyond the First Brillouin Zone simulated with inertia gradient continua
摘要： Nano-scale wave dispersion beyond the First Brillouin Zone is often observed as descending branches and inflection points when plotting frequency or phase velocity against the wave number. Modeling this with discrete chain models is hampered by their restricted resolution. A continuum model equipped with higher-order inertia gradients is here developed as a suitable and versatile alternative. This model can be derived from discrete chain models, thereby providing a lower-scale motivation for the higher-order gradient terms. The derived gradient model is without free parameters, as the material constants are calculated a priori by minimising the error with respect to the discrete chain response. Unlike asymptotic approximations that provide a best fit for vanishing wave numbers, the error is here minimised over the entire range of reduced wave numbers 0 to 1, which leads to a much improved accuracy beyond the First Brillouin Zone. The new gradient model has been validated against (i) phonon dispersion curves measured through neutron scattering experiments in bismuth, aluminum, and nickel and (ii) Molecular Dynamics (MD) flexural wave propagation simulations of carbon nanotubes. The model captures all qualitative aspects of the experimental and MD dispersion curves without requiring a bespoke curve fitting procedure. With the exception of one set of MD results, the accuracy of the gradient model is very good.
关键词： Nano-scale wave dispersion,Molecular Dynamics,First Brillouin Zone,inertia gradient continua,carbon nanotubes,phonon dispersion curves
更新于2025-09-10 09:29:36
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Optical Tunability of Silver-Dielectric-Silver Multi-Layered Cylindrical Nanotubes Using Quasi-Static Approximation
摘要： Local surface plasmon resonances (LSPRs) of silver-dielectric-silver multi-layered (SDS-ML) nanotubes are studied by theoretical calculations. Based on quasi-static approximation, the absorption cross section of SDS-ML nanotubes is plotted as a function of wavelength. The results show that SDS-ML nanotubes exhibit strong coupling between the cylindrical silver and nanotubes. The absorption spectra of LSPRs are strongly influenced by changing the radius of the inner core and outer nanotube shell. The longer wavelength is red-shifted by increasing the radius of the inner core and outer shell, while the short wavelength shows the opposite properties. These phenomena are explained by the plasmon hybridization theory. In addition, for clarity, the distributions of electric field intensity at their plasmon resonance wavelengths are also studied.
关键词： Local surface plasmon resonances,quasi-static approximation,silver-dielectric-silver multi-layered nanotubes,plasmon hybridization theory
更新于2025-09-09 09:28:46
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Enhanced Photocatalytic Activity of TiO <sub/>2</sub> Nanotubes with Acid Treatments
摘要： In this work, we present the enhanced photocatalytic activity of TiO2 nanotubes (TNTs) by hydrothermal method with acid treatment. Firstly, TNTs were synthesized by using a hydrothermal method from commercial TiO2 powder in a 10 M NaOH solution at 130 (cid:3)C for 22 hours. The synthesized solid product after synthesis was then treated by three different post washing procedures: (i) distilled water, (ii) 2 M HCl + distilled water, and (iii) 2 M HNO3 + distilled water. The morphology, structural, and chemical composition of the washed TNT nanostructures were characterized by using the transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray diffraction (EDX). The photocatalytic activities of TNTs were then evaluated through the photocatalytic degradation of the methylene blue (MB) solution. The results reveal that the post washing procedures affect the uniformity, Na impurity of the achieved TNTs and the reduction of Na impurity content, makes for ef?cient photocatalytic properties.
关键词： Photocatalytic,Titanium Dioxide Nanotubes,Hydrothermal Process,Washing
更新于2025-09-09 09:28:46
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Excitation-Tunable Tip-Enhanced Raman Spectroscopy
摘要： Tip-enhanced Raman spectroscopy is a powerful tool to investigate chemical composition, for obtaining molecular information, and for recording images with a spatial resolution on the nanometer scale. However, it typically has been limited to a fixed excitation wavelength. We demonstrate excitation-dependent hyperspectral imaging by implementing a wavelength tunable laser to our TERS setup. Varying the excitation wavelength during TERS experiments is a key to perform spatially resolved resonant Raman scattering (RRS) with nanometer resolution, which enables mapping of transition centers and to study for example the quantum properties of electrons and phonons. To present the application potential and to verify the setup, we recorded excitation-dependent hyperspectral nanoimages of a densely packed film of carbon nanotubes (CNTs) on an Au surface and use the spectral position and intensity of the radial breathing modes for a unique assignment of the CNTs. We succeeded in identifying and imaging at least nine different tube species. The nanoimages revealed the exact position and the distribution of certain CNTs inside the film. e-TERS will have manifold application in nanoimaging, for chemical analysis and electronic studies on the nanometer scale, making it highly interesting in fields ranging from biomedicine and chemistry to material science.
关键词： nanoimaging,Tip-enhanced Raman spectroscopy,resonant Raman scattering,carbon nanotubes,hyperspectral imaging
更新于2025-09-09 09:28:46
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B7 liquid crystal filament growth in the presence of carbon nanotubes
摘要： Liquid crystal phases formed from bent-core mesogens have attracted much interest of the liquid crystal research community, due to the manifestation of chirality effects from achiral molecules. One of the most elusive of the bent-core phases is the B7 phase, which at its early stage often forms in a helical filament fashion. We investigate the growth of such filaments in the presence of single-walled nanotubes to elucidate possible effects on the growth dynamics and helicity of B7 helical filaments. It is found that the filament width slightly decreases in comparison to the neat B7 material, suggesting a more tightly bound structure around the nanotubes, with the nanotubes likely acting as the core of the helical filament. No effects on pitch or periodicity of the helical superstructure is observed. The filament growth velocity quickly decreases as nanotubes are added to the B7 phase, indicating that a more tightly bound structure needs a longer time of formation. An observed buckling instability is of interest as a microscopic example for the study of nonlinear dynamics theories of filaments. The present investigation is thus of general importance for nanoparticle directed growth of filaments, which has applications in biomolecular growth and high tensile strength fibres.
关键词： bent-core mesogens,nanotubes,buckling instability,B7 phase,liquid crystal,filament growth
更新于2025-09-09 09:28:46
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Distributed Strain Sensing Using Electrical Time Domain Reflectometry With Nanocomposites
摘要： The objective of this study is to validate distributed strain sensing using electrical time domain reflectometry (ETDR) with multi-walled carbon nanotube (MWCNT)-based thin film sensing elements. The proposed ETDR sensor composed of two types of transmission lines: parallel-wire-type transmission line and parallel-plate-type transmission line with MWCNT-based sensing elements. The hypothesis was that the greater strain-induced impedance changes of the nanocomposite would enhance ETDR sensing performance. In this paper, four different types of ETDR sensing elements were subjected to one-cycle uniaxial tensile strains to validate strain sensing. Three sensing elements were then integrated in an ETDR setup, and strain patterns were applied for validating their distributed strain sensing behavior.
关键词： transmission line,Carbon nanotubes,thin film,strain sensing,electrical time domain reflectometry
更新于2025-09-09 09:28:46
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Influence of Defects in Boron Nitride Nanotubes in the Adsorption of Molecules. Insights from B3LYP-D2* Periodic Simulations
摘要： The adsorption of H2O, NH3 and HCOOH as polar molecules and C6H6 and CH4 as non-polar ones on a series of zig-zag (6,0) single-walled boron nitride nanotubes (BNNTs) both being defect-free (P_BNNT) and containing defects at the nanotube walls has been studied by means of B3LYP-D2* periodic calculations. We focused on defects derived from monovacancies of B (N-rich_BNNT) and N (B-rich_BNNT) atoms and also on Stone-Wales defects (SW_BNNT). The adsorption of polar molecules with defective BNNTs is generally based on dative interactions and H-bonding, and their adsorption energies strongly depend on the type of BNNT. N-rich_BNNT is the most reactive nanotube towards adsorption of polar molecules, as in all cases deprotonation of the polar molecules is spontaneously given upon adsorption. The strength in the adsorption energies is followed by B-rich_BNNT, SW_BNNT and P_BNNT. Adsorption of non-polar molecules is mainly dictated by dispersion interactions, and, accordingly, the adsorption energies are almost constant for a given molecule irrespective of the type of nanotube.
关键词： adsorption,vacancies,periodic simulations,boron nitride nanotubes,DFT,Stone-Wales defect
更新于2025-09-09 09:28:46
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High Photoconversion Efficiency Obtained from Novel TiO2 Photoanodes
摘要： High photoconversion efficiency for photoelectrochemical water splitting was obtained using nanocaves TiO2 and highly uniformed TiO2 nanotubes. The photoanodes were synthesized via electrochemical anodization of a titanium foil in a glycerol-based solution containing NH4F at 10 V. Pulse electrodeposition was used to incorporate Cu ions into the uniform TiO2 nanotubes. The photoconversion efficiency performance was examined under simulated visible light illumination (? ≥ 380 nm) in a 1 M solution of NaOH. The photocurrent density, the Mott-Schottky, the EIS, and the photoconversion efficiency measurements were determined. The highest photocurrent density i.e. 5.77 mA cm-2 at 1.23 V vs. RHE was obtained from nanocaves TiO2 photoanode. The incorporation of Cu resulted in a reduction in photocatalytic activity of the oxygen evaluation reaction (OER) and an increase of the hydrogen evolution reaction (HER).
关键词： Titanium dioxide nanotubes,water splitting,Photocurrent density,Photoelectrochemical,Anodization
更新于2025-09-09 09:28:46