Single-walled Nanotubes Research Articles

Size-Dependent Vibration Problem of Two Vertically-Aligned Single-Walled Boron Nitride Nanotubes Conveying Fluid in Thermal Environment Via Nonlocal Strain Gradient Shell Model

The free vibration behavior of two fluid-conveying vertically-aligned single-walled boron nitride nanotubes are studied in the present paper via the nonlocal strain gradient piezoelectric theory in conjunction with the first-order shear deformation shell assumption in thermal environments. It is supposed that the two adjacent boron nitride nanotubes are coupled with each other in the context of linear deformation by van der Waals interaction according to Lennard–Jones potential function. To achieve a more accurate modeling for low-scale structures, both hardening and softening effects of materials are considered in the nonlocal strain gradient approach. The motion equations and associated boundary conditions are derived by means of Hamilton’s variational principle, then solved utilizing differential quadrature method. Numerical studies are done to reveal the effect of different boundary conditions, size scale parameters, aspect ratio, inter-tube distance, and temperature change on the variations of dimensionless eigenfrequency and critical flow velocity.

Properties of Scalable Chirped-Pulse Optical Comb in Erbium-Doped Ultrafast All-Fiber Ring Laser

We report on a scalable chirped-pulse Er-doped all-fiber laser, passively mode-locked by single-wall carbon nitride nanotubes. The average output power is ~15 mW, which corresponds to a peak power of ~77 W, and pulse energy of ~1.9 nJ and was achieved using a single amplification stage. We observed chirped-pulse generation with a duration of ~24.6 ps at a relatively low repetition rate of ~7.9 MHz, with a signal-to-noise ratio of ~69 dB. To characterize the short-term stability of the obtained regime, we have measured the relative intensity noise of the laser, which is <−107 dBc/Hz in the range of 3 Hz–1000 kHz. It should be noted that the standard deviation of root mean square of average power does not exceed a magnitude of 0.9% for 3 h of measurement.

(Invited) Anodic TiO2 Nanotube Layers: Efficient Photocatalyst

The self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 15 years motivated by their possible range of applications including photocatalysis, solar cells, hydrogen generation and biomedical uses [1,2]. The synthesis of these 1D TiO2 nanotube layers is carried out by a conventional electrochemical anodization of valve Ti metal sheet.Among other TiO2 nanomaterials, these nanotube layers stand out due to their directionality, tunability of dimensions, ability to absorb significant amount of incident light and the possibility to utilize nanotube interiors and exteriors for decoration-coating of secondary materials.One of the most significant applications of TiO2 nanomaterials is photocatalysis, which is very effective to decompose various pollutants (e.g. dyes) and kill bacteria [3,4].The presentation will focus on the utilization of the nanotube layer for photocatalytic removal of various species in the liquid phase [5, 6] as well as gas phase [7]. We will demonstrate the photocatalytic performance of recently developed single-wall TiO2 nanotubes and single-tube TiO2 powders [8]. We will also show that various modifications of nanotube ssecondary materials have a positive influence on photo-electrochemical properties of nanotube layers [9,10]. Experimental details and some recent photocatalytic results will be presented and discussed.

(Invited) Exploiting Counterion Chemistry for Enhanced Thermoelectric Carbon Nanotube Networks

Careful control of the charge-carrier density is required to optimize the thermoelectric performance of carbon nanotube networks. This control is typically provided through charge injection from chemical dopants that reside within the doped network. We will build upon previous demonstrations of effective p-type doping by employing a series of novel charge-transfer dopants based on dodecaborane clusters appended with various organic moieties that control both the structure and redox properties of the dopant. The unique chemical and electronic structure of these dopants, compared to oxidants like triethyloxonium hexachloroantimonate (OA) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), allow for the electron extracted from the carbon nanotube to be localized on the dodecaborane cluster. This results in spatial separation of the negative counter-charge on the center of the dodecaborane cluster from the hole density injected into the carbon nanotube, which improves charge-carrier transport within the network. This enhanced transport results in an increase in the thermoelectric power factor that surpasses the previous best-in-class for enriched semiconductor single-walled nanotube thin film networks.

In Silico study of adsorption of penicillin antibiotic on the surface of single walled nitride boron nanotubes(SBNNT)

ObjectivesThe present study aimed to assess the adsorption of single-walled nitride boron nanotubes (SBNNT) with penicillin Antibiotic agent at the B3LYP/6–31 G (d) theoretical level. Materials and MethodsInitially, the structures of penicillin antibiotic and SBNNT were optimized. Afterward, with the molecular docking method and its ranking algorithm, the configuration of ten complexes with more negative binding energy and steady-state was calculated. Then, for the most stable configuration with SBNNT, IR calculations and molecular orbitals were performed on them. Adsorption energy and thermodynamic parameters were calculated, molecular orbitals, and related parameters showed that the adsorption of penicillin antibiotic on SBNNT is a thermogenic and spontaneous process. This process was performed at 298 K and 1 atm. The Calculations of thermodynamic parameters and molecular orbitals analysis were performed. In addition, some important parameters were assessed, including the adsorption energy, Gibbs free energy changes (ΔGad), enthalpy (ΔHad) variations, chemical hardness, energy gap, and electrophilicity. ResultsAccording to the results, Gibbs free energy changes (ΔGad), enthalpy (ΔHad) variations, of These Interactions were negatives at 298 K and 1 atm. ConclusionsSince according to the obtained results for adsorption of Penicillin on the SBNNT in every 10 complexes obtained were spontaneous at 298 K and 1 atm, also Findings of molecular orbital analysis, indicated that SBNNT could be utilized as a sensing material in the construction of thermal and electrochemical sensors for Penicillin determination.

The possible structure and electronic structure of zigzag silicon nanotubes doped with group V elements

We performed spin-polarized density functional theory (DFT) calculations to study the stable structures and electronic structure of X-doped (X = N, P, As, Sb and Bi) single-walled silicon nanotubes (SiNTs). Intrinsic SiNTs with small diameters can exist stably and maintain a smooth surface structure. However, due to the addition of impurities, small-diameter nanotubes cannot maintain a stable tube structure. In addition to Bi, the doping of group five elements can effectively improve the stability of (14, 0) SiNTs. Moreover, the addition of group V elements makes SiNTs produce impurity levels at the Fermi level, thereby reducing the band gap. The doping of P, As, Sb, and Bi even led to the transformation of SiNTs from semiconductors to metals, and the energy level shift appears in N-doped SiNTs.

Indirect-to-direct band gap crossover of single walled MoS2 nanotubes

Using density functional theory, the electronic structures of single walled molybdenum disulfide nanotubes (MoS2 NTs) were investigated. The armchair MoS2 NTs are indirect gap semiconductors for diameters up to approximately 5.2 nm, while those with larger diameters are direct gap semiconductors with band edges located in the vicinity of k = 2π/3. This finding implies that MoS2 NTs with large diameters should exhibit similar photoluminescence to 2D monolayer MoS2 sheets. This indirect-to-direct band gap crossover accounts for the relative upward shift of the valence band peak at the Γ point in small diameter NTs, owing to the tensile strain arising from curvature.

Functionalization of single-wall BC2N nanotubes by using amino acid: DFT study

Functionalization of single-wall BC2N nanotubes by using amino acid: DFT study

Polymer composite materials with electrically conductive and antistatic properties

The influence of special brands of carbon black and carbon single-wall nanotubes on the electrophysical, physico-mechanical and rheological properties of a PE-based polymer composite material is investigated.

Atomistic Study on the Mechanical Behavior of Silicon-Base Nanotubes

Recently, silicon nanotubes (SiNTs) have been successfully synthesized and have attracted many researchers to work on the different aspects of them. In the present study, the stress-strain curve along with the Young’s modulus as a significant mechanical property of single walled silicon nanotubes at different diameters are determined. The simulation is performed by the use of molecular dynamics based on the Tersoff-Brenner many-body potential energy function. The results of the total strain energy of nanotubes as an accurate and effective methodology are used to establish appropriate expressions for evaluating Young’s modulus of the nanotubes.

Mechanical properties of group IV single-walled nanotubes: a finite element approach based on the density functional theory.

In this article, the density functional theory is applied to characterize the mechanical properties of single-walled nanotubes of group IV of the periodic table. These materials include carbon nanotube, silicon nanotube, germanium nanotube, and stanene nanotube. (10,10) armchair nanotube is selected for the investigation. By establishing a link between potential energy expressions in molecular and structural mechanics, a finite element approach is proposed for modeling nanotubes. In the proposed model, the nanotubes are considered as an assemblage of beam elements. Young's modulus of the nanotubes is computed by the proposed finite element model. Young's modulus of carbon, silicon, germanium, and tin nanotubes are obtained as 1029, 159.82, 83.23, and 83.15GPa, respectively, using the density functional theory. Also, the finite element approach gives the values as 1090, 154.67, 85.2, and 82.6GPa, respectively. It is shown that the finite element model can predict the results of the density functional theory with good accuracy.

Dopamine Drug Adsorption on the Aluminum Nitride Single-Wall Nanotube: Ab initio Study

The main challenge war focused on the detection of dopamine drug using a type of AlN nanotube sensor through density functional theory (DFT) calculations. The interaction behavior of dopamine (DA) and aluminum nitride single-wall nanotube (AlNNT) was investigated by using DFT calculation. For the most stable complex, the energy of adsorption of DA on the aluminum nitride single-wall nanotube’s surface was − 17.31 kcal/mol. DA adsorbs through an electrostatic mechanism on the AlNNT. The electrical conductivity of the nanotube has improved significantly by around 28.78 percent through the DA molecules’ absorption on the surface of nanotube. This increase can be used as a signal to detect a drug. Therefore, after DA drug adsorption, the AlNNT work function is reduced from 4.56 to 3.25 eV. Thus, the AlNNT can be both the electronic and work function-type sensor for DA detection. Compared with the gas phase, AlNNT-DA has more stability in aqueous media according to polarizable continuum model (PCM). Eventually, our results also uncovered that, in the presence of environmental contaminants, the AlNNT can selectively recognize the DA molecule.

Adjustable capillary imbibition enhancement in double-walled nanotubes with concentric tube length difference

Capillary imbibition of water plays a significant role in various applications at both the macroscopic and microscopic scales. However, it is still unclear whether capillary imbibition could be manipulated by the geometry structure of the nanotubes. In this paper, we adjust the concentric tube length difference ∆L of the double-walled nanotubes (DWNTs) to manipulate the capillary imbibition by molecular dynamics simulations. Three configurations are considered, i.e. ∆L = 0 (the common DWNT structure, labeled as configuration I), ∆L < 0 (configuration II, the inner tube is shorter than the outer tube), and ∆L > 0 (configuration III, the inner tube is longer than the outer tube). By comparing with the single-walled nanotube, it is found that the imbibition velocities of the water molecules in the DWNT are weakened 9.1% in configuration I and enhanced 30%–46.5% in configuration II and 10% in configuration III. By analyzing the microscopic structure of the water molecules, it is found that the imbibition velocity adjustment originates from the potential energy difference of the water molecules in the water reservoir and at the entrance of the nanotube at the nanotube cylindrical pore. An exponential relation between the imbibition velocity v L and the potential energy difference ΔE is obtained as . Furthermore, it is found that imbibition velocity is independent from the radius differences in all three configurations. Our results suggest a possible way to manipulate the capillary imbibition behavior and it has significant implications for water treatment, nano-switches, catalysis engines and biological sensors.

In Silico Adsorption of Lomustin anticancer drug on the surface of Boron Nitride nanotube

The present study aimed to assess the adsorption of Lomustin on the single-walled Boron Nitride nanotube which has been examined using Density Functional Theory (DFT), agent in a solvent phase (water) at the B3LYP/6-31G (d) theoretical level. Initially, the structures of Lomustin, Boron Nitride nanotube, and Lomustin complexes with Boron Nitride nanotubes were designed in Gauss View in three different conformers and were optimized geometrically, on which IR and frontier molecular orbital computations were carried out. Adsorption energy values, Gibbs free energy changes (ΔGad), adsorption enthalpy changes (ΔHad), and equilibrium thermodynamic constants were estimated. The results showed that adsorption process was spontaneous, exothermic and non-equilibrium. The values of specific heat capacity and adsorption enthalpy indicate that this nanostructure can be used to build new thermal sensors to measure Lomustin. The results of molecule orbitals estimations showed that energy gap, after drug absorption on the nanotube surface, decreased significantly and the values of chemical hardness and dipole moment were studied after the interaction of drug with adsorbent and the results showed that drug solubility and reactivity, after adsorption on Boron Nitride nanotubes, increased significantly. According to the obtained results for adsorption of Lomustin, this nanostructure can be used as a sensing material in building new electrochemical sensors to measure this drug.

Surface Carboxylation of a Boron-Carbon BC&lt;sub&gt;5&lt;/sub&gt; Nanotube in the Development of Sensor Devices

This article discusses the possibility of the fabrication of a highly sensitive sensor based on single-walled boron-carbon BC5 nanotubes surface modified with functional carboxyl groups (-COOH). The sensor potential for detection of alkali (lithium, potassium, and sodium) metals were investigated. The results of computer simulation of the interaction process between the sensor and an arbitrary surface of the modified tube containing atoms of the studied metals are presented. The carboxylated BC5 nanotube and a similarly modified BC3 nanotube was compared. The effect of boron atoms on sensory properties of the obtained system is concluded. The calculations were carried out within the framework of the density functional theory (DFT) method using the molecular cluster model. It has been proved that surface-modified boron-carbon nanotubes by carboxyl group show high sensitivity for the metal atoms under study and can be used as the sensor device.

Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes.

The present study investigates how the formation of melt-mixed immiscible blends based on PA6/SAN and PA6/PMMA filled with single walled nanotubes (SWCNTs) affects the thermoelectric (TE) properties. In addition to the detailed investigation of the blend morphology with compositions between 100/0 wt.% and 50/50 wt.%, the thermoelectric properties are investigated on blends with different SWCNT concentrations (0.25–3.0 wt.%). Both PA6 and the blend composites with the used type of SWCNTs showed negative Seebeck coefficients. It was shown that the PA6 matrix polymer, in which the SWCNTs are localized, mainly influenced the thermoelectric properties of blends with high SWCNT contents. By varying the blend composition, an increase in the absolute Seebeck coefficient, power factor (PF), and figure of merit (ZT) was achieved compared to the PA6 composite which is mainly related to the selective localization and enrichment of SWCNTs in the PA6 matrix at constant SWCNT loading. The maximum PFs achieved were 0.22 µW/m·K2 for PA6/SAN/SWCNT 70/30/3 wt.% and 0.13 µW/m·K2 for PA6/PMMA/SWCNT 60/40/3 wt.% compared to 0.09 µW/m·K2 for PA6/3 wt.% SWCNT which represent increases to 244% and 144%, respectively. At higher PMMA or SAN concentration, the change from matrix-droplet to a co-continuous morphology started, which, despite higher SWCNT enrichment in the PA6 matrix, disturbed the electrical conductivity, resulting in reduced PFs with still increasing Seebeck coefficients. At SWCNT contents between 0.5 and 3 wt.% the increase in the absolute Seebeck coefficient was compensated by lower electrical conductivity resulting in lower PF and ZT as compared to the PA6 composites.

Photoluminescence from Single-Walled MoS2 Nanotubes Coaxially Grown on Boron Nitride Nanotubes.

Single-walled and multiwalled molybdenum disulfide (MoS2) nanotubes have been coaxially synthesized on small-diameter boron nitride nanotubes (BNNTs) that are obtained from removing single-walled carbon nanotubes (SWCNTs) in heteronanotubes of SWCNTs coated by BNNTs. The photoluminescence (PL) from single-walled MoS2 nanotubes supported by core BNNTs is observed in this work, which evidences the direct bandgap structure of single-walled MoS2 nanotubes with a diameter around 6-7 nm. The observation is consistent with our DFT results that the single-walled MoS2 nanotube changes from an indirect-gap to a direct-gap semiconductor when the diameter of a nanotube is more than around 5.2 nm. On the other hand, when there are SWCNTs inside the heteronanotubes of BNNTs and single-walled MoS2 nanotubes, the PL signal from MoS2 nanotubes is considerably quenched. The charge transfer and energy transfer between SWCNTs and single-walled MoS2 nanotubes were examined through characterizations by PL, X-ray photoelectron spectroscopy, and Raman spectroscopy. Moreover, the PL signal from multiwalled MoS2 nanotubes is significantly quenched. Single-walled and multiwalled MoS2 nanotubes exhibit different Raman features in both resonant and nonresonant Raman spectra.

ZnO nucleation into trititanate nanotubes by ALD equipment techniques, a new way to functionalize layered metal oxides

In this contribution, we explore the potential of atomic layer deposition (ALD) techniques for developing new semiconductor metal oxide composites. Specifically, we investigate the functionalization of multi-wall trititanate nanotubes, H2Ti3O7 NTs (sample T1) with zinc oxide employing two different ALD approaches: vapor phase metalation (VPM) using diethylzinc (Zn(C2H5)2, DEZ) as a unique ALD precursor, and multiple pulsed vapor phase infiltration (MPI) using DEZ and water as precursors. We obtained two different types of tubular H2Ti3O7 species containing ZnO in their structures. Multi-wall trititanate nanotubes with ZnO intercalated inside the tube wall sheets were the main products from the VPM infiltration (sample T2). On the other hand, MPI (sample T3) principally leads to single-wall nanotubes with a ZnO hierarchical bi-modal functionalization, thin film coating, and surface decorated with ZnO particles. The products were mainly characterized by electron microscopy, energy dispersive X-ray, powder X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. An initial evaluation of the optical characteristics of the products demonstrated that they behaved as semiconductors. The IR study revealed the role of water, endogenous and/or exogenous, in determining the structure and properties of the products. The results confirm that ALD is a versatile tool, promising for developing tailor-made semiconductor materials.

Modeling interactions of dsDNA inside single-walled nanotubes

Nanotubes (NTs) have unique physicochemical properties, and therefore, they have found various applications, especially in medicine and electronics. This study models the interaction of a double-stranded deoxyribonucleic acid (dsDNA) molecule inside carbon, boron nitride, silicon, molybdenum disulphide (MoS2), and tungsten disulphide (WS2) single-walled NTs by using the Lennard-Jones potential and a continuum approach. Explicit analytical expressions for the interaction energy are obtained to determine the preferred minimum-energy position of the dsDNA molecule inside the NTs. Furthermore, the encapsulation behavior of the dsDNA molecule inside these five types of NTs is compared. The results indicate that the encapsulation of the dsDNA molecule inside the NTs depends on the NT diameter. The results also indicate that DNA can be encapsulated inside NTs for applications in biosensors, drug and gene delivery systems, and biomaterials as well as for detecting biomolecules for biotechnology and medical science applications.

Hygro-thermo-mechanical vibration of two vertically aligned single-walled boron nitride nanotubes conveying fluid

The nonlocal strain gradient theory, when combined with the first-order shear deformation theory, provides many capabilities in size-dependent structures. The aim of the present study is evaluation of the free vibration behavior of two vertically aligned fluid-conveying single-walled boron nitride nanotubes in hygrothermal environments considering slip boundary condition based on Knudsen number. These two adjacent nanotubes are coupled in the context of linear deformation through van der Waals interaction according to Lennard–Jones potential function. Actually, the contribution of the present work, compared with those previously reported, is investigating the simultaneous effect of hygrothermal loading and slip boundary condition on the dynamic behavior of two vertically aligned fluid-conveying single-walled boron nitride nanotubes. As an additional step to achieve a more accurate model of low-scale structures, both hardening and softening effects of materials are taken as important variables in the nonlocal strain gradient approach. To derive the motion equations and associated boundary conditions, Hamilton’s variational principle is used. The equations are then solved with the aid of differential quadrature method. Numerical studies are also performed to depict the effects of a number of parameters such as boundary conditions, size scale, aspect ratio, inter-tube distance, and temperature alteration on the variations of dimensionless eigenfrequency and critical flow velocity.