Zigzag Single-walled Carbon Nanotubes Research Articles

Chirality distribution of single-walled carbon nanotubes grown from gold nanoparticles

Au nanoparticles with diameters about 1.4 nm were dispersed onto porous Si3N4 grids and applied for growing single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition. Particularly, SWCNTs with diameters in the range of 0.75–1.8 nm were produced at a reaction temperature of 700 °C using CO as the carbon precursor. Nanobeam electron diffraction characterizations revealed that most of the SWCNTs have large chiral angles and zigzag SWCNTs were hardly detected. Density functional theory calculations showed that the SWCNT-Au interface formation energy and the SWCNT growth kinetics account for the enrichment of large chiral angle SWCNTs in the product.

Assessment of drug loading and release efficiencies of zigzag (8, 0) single-walled carbon nanotube as a Bendamustine hydrochloride drug delivery system in silico: DFT approach

ABSTRACT In view of non-immunogenic containers of biomolecules, we investigated zigzag (8, 0) single-walled carbon nanotube (SWCNT) as a vehicle for the selectivity delivery of Bendamustine hydrochloride (Benda-HCl) drug to the cell target in silico using the density functional theory (DFT) approach. During drug interaction with the carbon nanotube surface, at about 56 kJ/mol of energy is liberated in the most stable structure of the Benda-HCl@SWCNT complex. Therefore, there is an attractive van der Waals (vdW) interaction between the drug molecule and SWCNT during the exothermic adsorption. The kinetic and thermodynamic stability of the Benda-HCl@SWCNT complex is evaluated with the reactivity descriptors such as individual energy change of donor (ΔE B(A)), the fractional number of electrons (ΔN), the overall stabilisation energy (ΔE SE) and the individual energy change of acceptor (ΔE A(B)). The analysis of the electronic properties shows that no sensible charge transfer occurs between the nanotube and the drug molecule due to the physisorption process. Furthermore, the binding affinity of the drug molecule to SWCNT is decreased in an acidic environment. The findings of the present research work suggest that carbon nanotube can be effectively utilised as a Bendamustine hydrochloride drug delivery vehicle. Abbreviations: Benda-HCl: bendamustine hydrochloride; BSSE: basis set superposition error; DFT: density functional theory; E inter: interaction energy; HOMO: the highest occupied molecular orbital; LUMO: the lowest unoccupied molecular orbital; NBO: natural bond orbital analysis; PDOS: projected density of state; TDOS: total density of states

Impact of edge functionalization on electron field-emission characteristics of carbon nanotubes: A theoretical approach

A theoretical approach using first-principle calculations of the density of states (DOS) of functionalized carbon nanotubes (CNTs) is carried out to understand their enhanced electron field emission (FE) properties. The theoretical functionalization of CNTs is perceived using hydrogenation (H/O–H) and oxidation methods. In order to investigate the enhancement in the FE properties of functionalized CNTs, both single-walled carbon nanotubes (SWCNT) and double-walled carbon nanotubes (DWCNT) are studied. The work function is observed to be more decreased in case of zigzag SWCNT (φ = 3.32 for oxygenated SWCNT) as compared to others SWCNT. The dependence of DOS on zigzag/armchair edge functionalization has also been investigated to reveal the impact of DOS on FE. The observed results indicate that edge functionalization of CNTs leads to significant changes in the band structure, DOS, and work functions. The shifting of DOS away from the Fermi level and decrease in work function is evidenced owing to the reduction in the curvature effect of CNT. Also, due to enhanced DOS near the Fermi level, making them a better proposition for FE applications. Our calculations provide an in-depth insight into the functionalization mechanism to understand the enhanced FE properties from them.

Nature of Oxygen Adsorption on Defective Carbonaceous Materials

Plane-wave density functional theory has been used to study oxygen adsorption on graphene, graphite, and (12,0) zigzag single-walled carbon nanotubes with and without Stone–Wales (SW) and single-vacancy (SV) defects to understand the role of defects on carbonaceous material reactivity. Atomic oxygen adsorption leads to the formation of an epoxide on defect-free graphene and graphite and an ether on the exterior wall of carbon nanotubes and SW-defected materials. O2 chemisorption is endothermic on defect-free graphene and graphite and slightly exothermic on defect-free nanotubes. O2 chemisorption energies are predicted to be −1.1 to −1.4 eV on an SW defect and −6.0 to −8.0 eV on an SV defect. An SW defect lowers the energy barriers by 0.90 and 0.50 eV for O2 chemisorption on graphene and nanotubes, respectively. The formation of a C–O–O–C group is important for O2 dissociation on defect-free and SW-defected materials. The energy barrier is less than 0.30 eV on an SV defect. The more reactive SW defect toward O adsorption on graphene is mostly due to the strained defective carbon atoms being able to donate more electrons to an O to form an ether. The larger 2s character in the hybrid orbitals in an ether than in an epoxide makes the ether C–O bond stronger. Stronger C–O binding on an SW-defective carbon nanotube than on a defect-free nanotube is in part due to more flexibility of the defect to release the epoxide ring strain to form an ether.

Computational Modelling of SO2 and H2S gas interacting with small diameter Au-doped (5, 0) zig-zag single-walled carbon nanotubes

An ab initio density functional theory (DFT) is employed to explore the effect of adsorption of SO2 and H2S gases on gold-doped small diameter (5,0) zig-zag single-walled carbon nanotubes. Au-SWCNT nanostructures are extremely sensitive to the presence of both SO2 and H2S gases. Charge is transferred from the Au-SWCNT to the SO2 upon the adsorption of the gas molecules onto the Au-SWCNTs surface. There is a decrease in the energy bandgap of the Au-SWCNT. As a consequence, the electrical conductivity of Au-SWCNTs/SO2 is extremely enhanced. On the contrary, the adsorption of H2S gas onto the surface of the gold-doped nanotube provokes charge transfer from H2S to the Au-SWCNT. Another interesting observation is that the energy bandgap of AuSWCNT increases upon the adsorption of the H2S gas molecules onto the Au-SWCNT surface, thereby decreasing the electrical conductivity of the Au-SWCNT/H2S nanostructure. Citation: Elloh, V. W., Boadu, E. O., Ofosuhene, D. F. and Arhin, I. (2021). Computational Modelling of SO2 and H2S gas interacting with small diameter Au-doped (5, 0) zig-zag single-walled carbon nanotubes.International Journal of Technology and Management Research (IJTMR), Vol. 6 (2): Pp.87-95. Received: March 20, 2021Accepted: September 1, 2021

Delivery of Capecitabine by Single-Walled Carbon Nanotube

Application of the zigzag (24, 0) single-walled carbon nanotube (SWCNT) in delivery of carbamate and imine tautomers of capecitabine is investigated via quantum mechanical geometry optimizations followed by chemical shielding calculations. Torsion angle between ribose and cytosine rings is very close to the experimental value in both tautomers. This suggests that relative orientation of these rings is independent of presence of SWCNT. Their carbon nuclei become closer to the tube’s internal surface by about 1Å, when going from cytosine ring to aliphatic tail. Their cytosine and ribose rings bend so that fluorine atoms and 2[Formula: see text]-OH group form ion-[Formula: see text] interaction with the surface. Calculated binding energies aside from observation of these sorts of interactions in these tautomers can propose SWCNT as their potent delivery tool. Most of the obtained conclusions are manifested in the observed trends for calculated chemical shielding values. They make connections among the reported experimental and computational distributions of chemical shielding values inside SWCNTs.

Metallic carbon nanotube quantum dots with broken symmetries as a platform for tunable terahertz detection

Generating and detecting radiation in the technologically relevant range of the so-called terahertz gap (0.1–10 THz) is challenging because of a lack of efficient sources and detectors. Quantum dots in carbon nanotubes have shown great potential to build sensitive terahertz detectors, usually based on photon-assisted tunneling. A recently reported mechanism combining resonant quantum dot transitions and tunneling barrier asymmetries results in a narrow linewidth photocurrent response with a large signal-to-noise ratio under weak THz radiation. That device was sensitive to one frequency, corresponding to transitions between equidistant quantized states. In this work we show, using numerical simulations together with scanning tunneling spectroscopy studies of a defect-induced metallic zigzag single-walled carbon nanotube quantum dot, that breaking simultaneously various symmetries in metallic nanotube quantum dots of arbitrary chirality strongly relaxes the selection rules in the electric dipole approximation and removes energy degeneracies. This leads to a richer set of allowed optical transitions spanning frequencies from 1 THz to several tens of THz, for a ∼10 nm quantum dot. Based on these findings, we propose a terahertz detector device based on a metallic single-walled carbon nanotube quantum dot defined by artificial defects. Depending on its length and contacts transparency, the operating regimes range from a high-resolution gate-tunable terahertz sensor to a broadband terahertz detector. Our calculations indicate that the device is largely unaffected by temperatures up to 100 K, making carbon nanotube quantum dots with broken symmetries a promising platform to design tunable terahertz detectors that could operate at liquid nitrogen temperatures.

Vibrational and electronic properties of (5,0) zigzag and (5,5) armchair carbon and SiC nanotubes using density functional theory

We have performed optimization of (5,0) zigzag and (5,5) armchair single-walled carbon nanotube and SiC nanotube using density functional theory at zero spin and high spin values. Further, Infrared and Raman spectra, highest occupied and lowest unoccupied molecular orbitals and their gap and natural bond orbital analysis were carried out at optimized structures of these materials. Three different exchange and correlation functionals PBE, LSDA and HCTH along with cc-pVDZ basis set were used. For conspicuous normal modes assignments of both the (5,0) zigzag and (5,5) armchair single-walled carbon nanotube and SiC nanotube, potential energy distributions of the normal modes were calculated using normal coordinate analysis. The diameter of carbon nanotube and SiC nanotube in (5,0) zigzag form were optimized at 4.0 Å and 5.0 Å respectively and in (5,5) armchair form were optimized at 7.0 Å and 8.0 Å respectively at all the three level of theories.

A theoretical study of (9, 0) Singlewalled Carbon Nanotubes using quantum mechanical techniques

First principles simulation studies using the density functional theory have been performed on (9, 0) Zigzag Singlewalled Carbon Nanotube (SWCNT) to investigate its electronic, optical and thermodynamic properties using CASTEP (Cambridge Sequential Total Energy Package) and DFTB (Density Functional based Tight Binding) modules of the Material Studio Software version 7.0. Various functionals and sub-functionals available in the CASTEP Module (using Pulay Density Mixing treatment of electrons) and various eigen-solvers and smearing schemes available in the DFTB module (using smart algorithm) have been tried out to chalk out the electronic structure. The analytically deduced values of the band gap obtained were compared with the experimentally determined value reported in the literature. By comparison, combination of Anderson smearing scheme and standard diaogonalizer produced best results in DFTB module while in the CASTEP module, GGA (General Gradient approximation) functional with RPBE (Revised-perdew-Burke-Ernzerh) as Sub-functional was found to be the most consistent. These optimized parameters were then used to determine various electronic, optical and thermodynamic properties of (9, 0) Singlewalled Nanotube. (9, 0) Singlewalled Nanotube, which is extensively being used for sensing NH3, CH4 & NO2, has been picked up in particular as it is reported to exhibit a finite energy band gap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies.

Numerical Simulation of Tensile Residual Stresses in SWCNT-Reinforced Polymer Composites

Abstract The residual stresses play a significant role in the mechanical properties and strengthening capability of nanocomposites. The present research aims to numerically investigate the residual stress relaxation in nanotube-reinforced polymers in response to mechanical tensile loading. The systems under study consist of the armchair and zigzag single-walled carbon nanotubes (SWCNT) embedded in a polymer matrix. The nanotubes and polymer matrix are assumed to be bonded by van der Waals interactions based on the Lennard-Jones (L-J) potential at the interface. The interactions between carbon atoms in the nanotube and nodes in the polymer matrix are modelled by equivalent springs. In order to evaluate the analysis of elastic-perfectly plastic using finite element (FE) modelling, first, relaxation of the plastic residual stresses on steel hemisphere in contact with a rigid flat surface was examined in a loading-unloading cycle and verified with available data. Afterwards, the residual stress relaxation in nanotubes with different space-frame structures was computed due to displacement-controlled loading. Finally, the stress state and the plastic residual stresses in the nanocomposite for different carbon nanotube content were analyzed and discussed during loading and unloading. Regarding the effect of tensile stress, it was revealed that nanotube structures have significant effects on the residual stresses created in the nanocomposite.

LED Device Based on Single-Walled Carbon Nanotube Arrays

The migration model of the (n, 0) zigzag SWNT is established on the basis of Mathiessen’s law to calculate carrier mobility, which are the foundation for performance analysis of electroluminescence light emission. The split-gate technique is used to create p-and n-doped regions in the single-walled carbon nanotube (SWNT) arrays that are separated by a gap with a width of several microns. The LED devices based on SWNT arrays using split-gate technique are fabricated and tested by using an optical measurement system. Compared to the LED with the central gate, the split-gate SWNT LED has enhanced the light generation efficiency of the intrinsic SWNT array segment by decreasing the potential barrier across the junction of the intrinsic SWNT array segment. The results demonstrate the luminescent principle of LED based on SWNT array in theoretical simulation and device measurement.

First-principles calculation of volatile organic compound adsorption on carbon nanotubes: Furan as case of study

Sensing of volatile organic compounds (VOCs) is a growing research topic because of the concern about their hazard for the environment and health. Furan is a VOC produced during food processing, and it has been classified as a risk molecule for human health and a possible biomarker of prostate cancer. The use of carbon nanotubes for VOCs sensing systems design could be a good alternative. In this work, a theoretical evaluation of the interactions between furan and zigzag single-wall carbon nanotubes takes into account different positions and orientations of the furan molecule, within a density-functional theory first-principles approach. The van der Waals interactions are considered using different exchange-correlation functionals (BH,C09, DRSLL and KBM). The results indicate that vdW-functionals do not significantly affect geometry; however, the binding energy and the distance between furan and nanotube are strongly dependent on the selected exchange-correlation functional. On the other hand, the effects of single and double vacancies on carbon nanotube are considered. It was found that the redistribution of charge around the single-vacancy affects the bandgap, magnetic moment, and binding energy of the complex, while furan interaction with a double-vacancy does not considerably change the electronic structure of the system. Our results suggest that to induce changes in the electronic properties of carbon nanotubes by furan, it is necessary to change the nanotube surface, for example, by means of structural defects.

Catalyst particle size dependent carbon nanotube cloning

The single walled carbon nanotube (SWCNT) cloning or its seeded growth with a catalyst particle docked on one of its ends was proposed as the ultimate solution for chirality-specific SWCNT synthesis and, therefore, revealing the effect of catalyst particle size on the robustness of the SWCNT cloning is crucial for experimental designs. Through systematic atomic simulations, we have clearly demonstrated that the robustness of SWCNT cloning depends on both the chiral angle of the SWCNT and the ratio of the diameters between the SWCNT and the docked catalyst particle. The zigzag (ZZ) or near ZZ SWCNTs are highly sensitive to the size of the docked catalyst particle. A small change of the catalyst particle size could lead to a variation of the SWCNT’s chirality. In contrast, armchair (AC) or near-AC SWCNTs are less sensitive to the size of the docked catalyst particle and able to maintain their original chiralities within ∼30% variation of the catalyst particle size. This study greatly deepens our understanding of SWCNT’s growth mechanism and provides a quantitative guidance for SWCNT cloning.

Vibration characteristics of zigzag FGM single-walled carbon nanotubes based on Ritz method with ring-stiffeners

In this study, Rayleigh–Ritz method is used for free vibrations of functionally graded carbon nanotubes based on Sander’s shell theory. The effects of various parameters for length-to-diameter ratio and height-to-diameter ratio for zigzag single-walled carbon nanotubes have been fully inspected. The frequency pattern with mass density per unit lateral area and in-plane rigidity has been calculated and found reverse order. The tube material is taken as functionally graded material and their material quantity is located by the polynomial volume fraction law. It is examined that the frequencies increase on increasing the ratio of height-to-diameter. Moreover, the impact of ring supports around the tube circumferential is studied for their various positions along tube axial length. These rings are restrained the radial displacement in the transverse direction.

The chemical shielding and magnetizability relationship in ‎potassium-doped (5,0) zigzag SWCNT nanotube

In this study, the relationship between daimagnetic shielding (σd), paramagnetic shielding (sp+s´p) and 13C isotropic shielding tensors 13C(σiso) with Mulliken, NBO and QTAIM atomic charges and also the relationship between chemical shielding and magnetizability in (5,0) zigzag single Walled Carbon Nanotube (SWCNT) as potassium doped and without potassium are investigated using Density Functional Theory (DFT) based on Periodic Boundary Condition (PBC) approach at the PBEPBE/6-31G(d) level of calculation.The doped (5,0) zigzag SWCNT with potassium is converted to n-type more stable Carbon Nanotube.There are linear relationship between the Mulliken, NBO and QTAIM atomic charges with 13C isotropic chemical shielding (σiso) and with dia-magnetic shielding (σd) in the SWCNT with and without potassium doping.The relationships are nonlinear between the total para-magnetic shielding (σp+σ´p) and all charges in the potassium doped SWCNT. In the both of structures of potassium doped and without potassium SWCNT, there are strong linear correlation between the Total-atomic magnetizability (Χ(Ω)) and 13C isotropic chemical shielding (σiso).

Comparative study of the electron–electron interactions on optoelectronic properties of carbon nanotube within orthogonal and nonorthogonal tight-binding model

We investigate the electron–electron (e–e) interactions effect on the optoelectronic properties of single-walled carbon nanotubes (SWCNTs). We study theoretically the effect of e–e interactions on the optoelectronic properties of zigzag carbon nanotubes and obtain some useful expressions for the band structure and optical absorption of nanotubes for the first nearest-neighbor (1NN) and second nearest-neighbor (2NN) approximation in tight-binding (TB) model. Our computational approach is based on combination of the orthogonal (o-TB) and nonorthogonal (n-TB) tight-binding method with Hubbard model for zigzag SWCNTs. In nonorthogonal tight-binding model we consider the effect of orbital overlap on optoelectronic properties of nanotubes. We also obtain the optical absorption spectrum of zigzag SWCNTs under e–e interactions effect with considering orthogonal and nonorthogonal tight-binding method for 1NN and 2NN approximation. We investigate optical absorption for the incident light polarized parallel to the tube axis and obtain all allowed optical transitions. Our results show some variations in the band structure and optical absorption spectrum of nanotubes under e–e interactions effect when we use orthogonal tight-binding model compare with nonorthogonal tight-binding model.

Emerging Scientific Field Detection Using Citation Networks and Topic Models—A Case Study of the Nanocarbon Field

In fields with high science linkage, such as the nanocarbon field, trends in academic papers are particularly important for identifying future technological trends. The use of the number of citations allows us to predict the qualitative trends on a paper-by-paper basis. At the same time, it is necessary to be able to comprehensively discuss both qualitative and quantitative aspects in the subject area. This study aimed to detect emerging areas in the nanocarbon field using network models and topic models. It was possible to not only construct a model that exceeded an 86.2% F1 measure but also to focus on an area that could not be detected by the prediction model. This was accomplished by focusing on paper units, such as the research on the chemical synthesis of zigzag single-walled carbon nanotubes. Thus, it is possible to obtain knowledge that contributes to diversified R&D strategies and innovation policies by considering the emergence of new fields from multiple perspectives.

Study of cage-like diamondoid polymeric nitrogen N10 confined inside single-wall carbon-nanotube

Cage-like diamondoid polymeric nitrogen N10 is captured at ambient conditions, when it is confined within a (8, 0) zigzag single wall carbon nanotube using ab initio calculations. The excellent energy-related properties, combined with the high polymeric nitrogen ratio (23.81 %) and the high energy density (3.26 kJ/g) of the N10@(8, 0)CNT structure, allows it as a typical high energy density material. The decomposed energy barrier and decomposition temperature of a confined N10 structure are 2.575 eV and 1100 K, respectively. The stable physical mechanism of the N10@(8, 0)CNT peapod structure is the complex electronic orbital hybridization interaction as well as the formed covalent bond between N10 and CNTs.

Covalent Functionalization of Single-Walled Carbon Nanotubes by the Bingel Reaction for Building Charge-Transfer Complexes.

Functionalization of nanotubes with donor and acceptor partners by the Bingel reaction leads to the formation of charge-transfer dyads, which can operate in organic photovoltaic devices. In this work, we theoretically examine the mechanism of the Bingel reaction for the (6,5)-chiral, (5,5)-armchair, and (9,0)-zigzag single-walled carbon nanotubes (SWCNTs), and demonstrate that the reaction is regioselective and takes place at the perpendicular position of (6,5)- and (5,5)-SWCNTs, and the oblique position of (9,0)-SWCNT. Further, we design computationally the donor-acceptor complexes based on (6,5)-SWCNT coupled with partners of different electronic nature. Analysis of their excited states reveals that efficient photoinduced charge transfer can be achieved in the complexes with π-extended analogue of tetrathiafulvalene (exTTF), zinc tetraphenylporphyrin (ZnTPP), and tetracyanoanthraquinodimethane (TCAQ). The solvent can significantly affect the population of the charge-separated states. Our calculations show that electron transfer (ET) occurs in the normal Marcus regime on a sub-nanosecond time scale in the complexes with exTTF and ZnTPP, and in the inverted Marcus regime on a picosecond time scale in the case of the TCAQ derivative. The ET rate is found to be not very sensitive to the degree of functionalization of the nanotube.

Buckling Failure Analysis of Defective Carbon Nanotubes Using Molecular Dynamics Simulation

Buckling failure under axial compression of defective single-walled carbon nanotubes (SWCNT) having (n, n) and (n, 0)-helicity is studied. Different types of vacancy defects such as monovacancy, bivacancies and tetravacancies as well as topological defect such as Stone–Thrower–Wales with their symmetric and asymmetric distribution are considered. The influence of these initial manufacturing defects on the compression properties is closely studied. The simulation results for armchair (11, 11) and zigzag (19, 0) tubes show that even a single missing atom reduces the buckling capacity of SWCNT. In general, buckling properties deteriorate higher by increasing the missing atoms and asymmetry distribution of vacancy cluster. Further, both vacancy defects and topological defects affect the compression capacity considerably. Zigzag carbon nanotubes (CNTs) have higher compression strength but are more sensitive to vacancy defects than compared to their armchair counterparts. STW defect has more detrimental effect on buckling capacity of armchair SWCNTs than its defective zigzag SWCNT counterparts.