BC3 Nanotubes Research Articles

Strong reactivity and electronic sensitivity of Au-decorated BC3 nanotubes toward the phenylpropanolamine drug

Strong reactivity and electronic sensitivity of Au-decorated BC3 nanotubes toward the phenylpropanolamine drug

Outstanding performance of transition-metal decorated BC3 nanotubes for high capacity CH4 storage

In this study, dispersion-corrected density functional theory calculations are utilized to examine the possibility of storing CH4 on BC3 nanotubes (BC3NTs) decorated with Sc or Y atoms. To assess metal binding, electronic characteristics, and CH4 adsorption capability, the adsorption energies, electron density difference maps, and charge-transfer values are obtained. According to our calculations, the (8,0) BC3NT functionalized with Sc and Y atoms has a maximum gravimetric density of 21.6 and 18.9 wt% for storing CH4 molecules, respectively. The modified van't Hoff equation is used to evaluate the temperature and pressure stability of CH4 adsorbed structures. The curvature effects have been found to play an important role in the CH4 adsorption on the functionalized BC3NTs, and the BC3NTs with a large curvature are likely more suitable for storing CH4 molecules. The results suggest Sc or Y functionalized BC3NTs can be regarded as novel materials for capturing and storing of CH4 molecules at ambient temperature and pressure.

Carbon nanotubes intercalated by metal atoms with impurity boron atoms as a basis for creating nanowires: theoretical research

Carbon nanotubes are one of the currently sought after nanotechnology materials. But the issue of controlling their physicochemical properties, in particular, for creating nanowires by intercalating metal atoms in them, has not yet been fully studied. In this case, there is an effective way to control the electronic energy characteristics — the introduction of impurity atoms. Boron is the most effective among this class of substituting elements. Therefore, the purpose of this article is to study the possibility of internal filling of carbon nanotubes with impurity boron atoms with various metal atoms and to determine the role of its concentration on the phenomena occurring in this case. Using the density functional theory, a model experiment was carried out on the introduction into the cavity of a nanotube of aluminum atoms, as well as alkali metals - lithium, sodium and potassium. The model experiment showed that in all cases the formation of a stable adsorption complex takes place, which can be considered as a model of a nanowire with multiple filling with atoms between the nanotube and metal atoms. At the same time, it was found that during the formation of complex compounds “nanotube — metal atom”, the electron density is redistributed in the system, namely, it is shifted from the B atoms of the metals to the surface of the nanotube, which leads to the formation of additional charge carriers transferred from the donor. Also, an analysis of the electron-energy structure made it possible to establish that the band gap for BC3 nanotubes narrows during the intercalation of metal atoms. This conclusion is extremely important for the needs of nanoelectronics, since it makes it possible to predict the more efficient use of carbon nanotubes with a higher concentration of impurity boron atoms to create nanodevices due to the appearance in them of conducting properties that are different from pure nanostructures, which are expressed in the appearance of additional charge carriers.

Outstanding Performance of Transition-Metal Decorated Bc3 Nanotubes for High Capacity Ch4 Storage

Outstanding Performance of Transition-Metal Decorated Bc3 Nanotubes for High Capacity Ch4 Storage

Potential application of BC3 nanotubes as a gamma-hydroxybutyric acid drug sensor: A DFT study

Using density functional theory (DFT) computations, the application of a BC3 nanotube was scrutinized to detect gamma-hydroxybutyric acid (GHB). After the adsorption of GHB the HOMO-LUMO gap reduces from 2.358 to 2.199 eV. The electrical conductance of GHB/BC3 nanotube complex is 486 times higher compared to that of the bare nanotube. Hence, the BC3 nanotube can yield an electronic sign after the adsorption of GHB, showing that it is a viable electronic sensor. The sensing response for the BC3 nanotube is 485, representing a high sensitivity. The sensing response is increased to 639, 746, and 906 for 2, 3, and 4 GHB adsorbed nanotube, respectively, indicating that the sensor response depends on the GHB concentration. The interaction between GHB and the BC3 nanotube in the ethanol solvent is strengthened.

A theoretical scenario for the mechanical failure of boron carbide nanotubes

Although the volume of research on carbon nanotubes (CNTs) has increased over a short period, less attention has been paid to other types of carbon-based nano-objects such as boron carbide (BC3) nanotubes (BC3NTs). In the present article, we modeled BC3NTs using molecular dynamics (MD) simulation to investigate the effects of chirality, wall number, diameter and temperature on the mechanical failure of BC3NTs, BC3 nanobuds and BC3NTs with different kinds of defects. In addition, we modeled the corresponding CNTs to validate the results and understand how the replacement of a quarter of the carbon atoms in the CNT by boron atoms affects the properties of the newly formed nanotube. The results showed that the variation of mechanical properties as a function of diameter and temperature was rather limited, regardless of chirality. The Young’s modulus, failure stress and failure strain of the zigzag single-walled BC3NTs (SWBC3NTs) were lower than the armchair ones, and were lower than those of the corresponding CNTs too. Furthermore, adding a second and third wall to the SWBC3NTs significantly improved their mechanical properties. Finally, we modeled BC3 nanobuds with 1 to 4 C60 attached to the surface of SWBC3NTs and observed that the properties decreased as the number of fullerenes increased. Moreover, considering defective SWBC3NTs revealed that two-atom vacancies and Stone-Wales defects resulted in the highest and lowest reduction of mechanical properties, respectively.

Gamma-butyrolactone drug detection by Al-doped BC3 nanotubes: A density functional theory study

Potential application of a pristine and Al-doped BC3 nanotube (Al-BC3NT) is explored in detection of gamma-butyrolactone (GBL) drug using DFT calculations. The GBL drug weakly adsorbed of the pristine BC3NT with adsorption energy (Ead) of −11.7 kcal/mol. The electronic properties of pristine BC3NT were not altered sensibly by the GBL adsorption, indicating that this tube is not a sensor. By Al-doping in the structure of BC3NT, the GBL interaction was strengthened (Ead = −21.8 kcal/mol). The Eg of Al-BC3NT dramatically declined from 2.38 to 1.93 eV, by GBL interaction. The electrical conductance of GBL/Al-BC3NT was 681 times higher than that of the bare Al-BC3NT. Thus, the Al-BC3NT yields an electronic signal after the GBL drug adsorption, being a promising electronic sensor. The recovery time for GBL drug desorption from the Al-BC3NT surface was predicted to be short (0.9 s). The interaction between the GBL and Al-BC3NT was strengthened in the ethanol solvent, and the Ead became more negative (−28.9 kcal/mol).

Functionalization of BC3 nanotubes with substituted pyridine: a DFT study

In the present study, surface modification of a BC3 nanotube (BC3NT) due to functionalization with substituted pyridine is studied using density functional theory (DFT) at B3LYP/6–31 G(d) computational level. The value of adsorption energy for the most stable structure is obtained −1.18 eV, indicating chemisorption process. Functionalization of BC3NT with pyridine derivatives, lead to significant changes in HOMO-LUMO energy gap of desired nanotube, that may be used for designing of promising nanosensor for detecting pyridine derivatives. Linear correlation has been established between adsorption energies of studied complexes with Hammett constant of adsorbed molecules.

Angle dependence of the shear behaviour of asymmetric carbon nanotubes

Asymmetric configurations of single-walled carbon nanotubes consist of a huge number of varieties compared to symmetric structures. A comprehensive characterization of all possible chiralities has been conducted in this research for the first time. In order to characterize asymmetric single-walled carbon nanotubes (SWCNTs), several finite element models have been employed to reach a logical relation between the geometry of the symmetric and asymmetric configurations and their shear modulus. Two groups of asymmetric structures have been selected to characterize asymmetric configurations. The chiral angle (θ) has been applied in this research to account for the shear behaviour of chiral configurations. The chiral angle perception has been used for a new insight of balancing between physical resemblances and shear behaviour of symmetric and asymmetric configurations. In the last section, the trend of the shear behaviour and chiral angle for asymmetric groups resulted in a general equation for predicting an asymmetric configuration by symmetric structures with high accuracy as the main novelty of the current study. This kind of characterization can be developed, not only for other mechanical properties of SWCNTs, but is also applicable for the characterization and the design of other composite nanotubes such as BN, BC3 and BC2N nanotubes.

Size effects on the infrared responses of boron carbide nanotubes

The spectral moment's method combined with a force constant model is used to calculate the polarized infrared spectra in single-walled BC3 nanotubes. We discuss the evolution of these spectra as a function of the diameter, chirality and length of nanotubes. Our work provides benchmark theoretical data for the assignment of experimental infrared spectra.

Tube-Length Dependence on Theoretical Raman Spectra of Single-Walled BC3 Nanotubes and Bundle Size Effect

Polarized Raman spectra of single-walled BC3 nanotubes (SBCNTs) are calculated as a function of their diameter, chirality, length, and bundle size using a classical force field combined with the bond-polarizability model. For isolated infinite tubes, we give a mathematical model to estimate their diameter from their Raman spectra. The tangential modes are sensitive to the tube chirality. The length shortening of the tube below ∼50 nm leads to the appearance of several additional Raman lines in the regions of breathing modes and tangential modes. For SBCNT bundles, the position of the radial breathing mode is significantly upshifted with respect to its position in isolated SBCNTs, and a specific bundle breathing-like mode is observed below 300 cm–1.

Study of atomic and molecular oxygen chemisorption on BC3 nanotubes with Stone–Wales defects using density functional theory

Density functional theory calculations are used to study the adsorption of chemical species including oxygen atom and oxygen molecule on the perfect and defective BC3 nanotubes. Stone–Wales topological defects with four different bond rotations have been examined. The adsorption of atomic oxygen is exothermic in all cases, while for the molecular oxygen, some sites showed endothermic adsorption. Comparative studies on the adsorption of these chemical species shows the maintenance of semiconductive behavior of nanotubes, except for one of the systems, the defected nanotube with a circumferential C–C bond rotation. In this system, the adsorption of molecular oxygen generates a half-metallic antiferromagnet. The results obtained in this paper are relevant for chemical sensing and spintronics applications.

Numerical study on electronic properties of a molecular wire based on BC3 zigzag nanotube

Electronic properties of a molecular wire based on a single-walled zigzag BC3 nanotube (n, 0) are investigated using tight-binding model combined with Green’s function theory and Landauer formalism. Our results indicate that these nanotubes have semiconducting properties. By increasing n, band gap of single-walled BC3 nanotubes are inversely proportional to nanotube diameter. On the other hand, a semiconductor–metal transition is demonstrated at a specific diameter in (n, 0) BC3 (if n is not in multiple of 3). Furthermore, the obtained results indicate that transmission probability mimics the behavior of density of states at all energy ranges. The current–voltage curves have nonlinear behavior and staircase structure. There is also a voltage drop in the first step on I–V characteristics with an increase in the diameter of the nanotube.

A theoretical insight into surface reactivity of nitrogen-doped BC3 nanotubes

Chemical doping with foreign atoms offers a practical path to modify the properties of host materials. Among them, nitrogen-doping plays an important role in regulating the electronic and mechanical properties of carbon-based materials. In the present study, density functional theory calculations are performed to predict the relative reactivities of different sites on the external surface of pristine and nitrogen-doped BC3 nanotubes (BC3NTs). The properties determined include the electrostatic potential VS(r) and average local ionization energy ĪS(r) on the surfaces of the investigated tubes. It is revealed that doping BC3NTs with N impurity can significantly improve the tube׳s surface reactivity and it allows their surface properties to be controlled. There is an obvious increase in the magnitude of VS(r) minima for all the BC3 doped with N atom, compared to the pristine one. There is a good correlation between chemisorption energies and average local ionization energies, indicating that ĪS(r) provides an effective means for rapidly predicting the relative reactivities of finite-sized BC3NTs. These results could be useful for designing and developing metal-free catalyst based on N-doped BC3NTs.

Exploring surface reactivity of phosphorous-doped (6,0) and (4,4) BC3 nanotubes: a DFT study

We report a density functional theory study on the electronic structure properties of pristine and phosphorous-doped (6,0) and (4,4) single-walled BC3 nanotubes (BC3NTs). We examine the usefulness of local reactivity descriptors to predict the reactivities of different carbon/boron atomic sites on the external surface of the tubes. Electrostatic potentials VS(r) and average local ionization energies ĪS(r) are computed on the surface of the investigated BC3NTs. A general feature of the systems considered here is that the magnitudes of negative VS(r) associated with carbon atoms tend to be stronger when the boron atom is substituted with a phosphorous atom. In order to verify the surface reactivity pattern based on the chosen reactivity descriptors, we calculated the reaction energies for the interaction of an H(+) ion or H radical with external surface of the (6,0) and (4,4) BC3NTs. It is clear that, for each nanotube studied, the reaction energies correlate well with the values of VS(r) and ĪS(r).

Adsorption of atomic hydrogen on the surface of the boron-carbon nanotubes

Results of theoretic studies of geometrical, electronic, and energy composition of monolayer boron-carbon BC3 nanotubes of the zig-zag type (n, 0) and the cylindrical symmetry are presented. The mechanism of adsorption of atomic hydrogen on the outer surface of the boron-containing BC3-nanotubes of the (6, 0) type is studied. The calculations are carried out on the basis of models of the ion-incorporated covalent-cyclic cluster using the semiempiric MNDO scheme and density functional (DFT) methods.

Fluorination of BC3 nanotubes: DFT studies

We have studied the adsorption of atomic and molecular fluorines on a BC3 nanotube by using density functional calculations. It was found that the adsorption of atomic fluorine on a C atom of the tube surface is energetically more favorable than that on a B atom by about 0.97 eV. The adsorption of atomic fluorine on both C and B atoms significantly affects the electronic properties of the BC3 tube. The HOMO-LUMO energy gap is considerably reduced from 2.37 to 1.50 and 1.14 eV upon atomic F adsorption on B and C atoms, respectively. Molecular fluorine energetically tends to be dissociated on B atoms of the tube surface. The associative and dissociative adsorption energies of F2 were calculated to be about -0.42 and -4.79 eV, respectively. Electron emission density from BC3 nanotube surface will be increased upon both atomic and molecular fluorine adsorptions due to work function decrement.

NH3 on a BC3 nanotube: effect of doping and decoration of aluminum

The adsorption of the NH3 molecule was investigated on pristine, Al-doped and Al-decorated BC3 nanotubes (BC3NT) using density functional theory calculations. It was found that NH3 prefers to be adsorbed on a B atom of the tube wall, releasing energy of 1.02 eV. Al-doping increases the acidity of the tube surface and, therefore, its reactivity toward NH3 so that the released energy in this case is about 1.62 eV, while decorating the BC3NT with Al atom decreases the acidity and reactivity. Although Al-doping has no significant effect on the electronic properties of the BC3NT, Al-decoration significantly reduces its HOMO/LUMO energy gap from 2.37 to 1.16 eV so that the tube becomes an n-type semiconductor. However, we believe that the acidity of the BC3NTs may be controlled by doping or decoration of Al atoms.

Electronic structure and surface reactivity of BC3 nanotubes from first-principle calculations

A theoretical study was carried out to investigate the electronic structure properties of pristine and nitrogen-doped (6,0) BC3 nanotubes (BC3NTs). We examine the usefulness of local reactivity descriptors to predict the reactivity of B/C atomic sites on the external surface of the tubes. The properties determined include Fukui function f(k) and local softness s(k) on the surfaces of the investigated tubes. Geometry optimization results reveal that nitrogen atom can be comfortably incorporated into the BC3 network. It is most likely associated with the triple-coordination characteristic of nitrogen atom, which can well match with the sp2-hybridized boron/carbon bonding structure. According to the values of f(k) and s(k) for the pristine BC3NT, the atoms in the edge regions show a different reactivity pattern than those in the middle portion of the nanotube. The nitrogen impurity can significantly improve the tube’s surface reactivity and it allows controlling their surface properties. We found an acceptable correlation between atomic hydrogen chemisorption energies and reactivity indexes, indicating that f(k) and s(k) provides an efficient means for rapidly estimating the relative reactivities of finite-sized BC3NTs.

Study of titanium adsorption on perfect and defected BC3 nanotubes using density functional theory

Density functional theory calculations were used to study the titanium (Ti) adsorption on perfect and defected (4, 0) BC3 nanotubes, considering Stone–Wales and vacancy defects. The binding energy values for these nanotubes were larger than the corresponding values for carbon nanotubes. The charge transfer from the Ti atom to nanotube was observed for all systems studied. The most exothermic binding process occurred for the Ti adsorption on a native VB defect, which showed minimum structural deformation with respect to a perfect BC3 tube. In the case of a nanotube with a reconstructed carbon vacancy, the adsorption of Ti generated a half-metallic anti-ferromagnet. The results obtained in this paper are relevant for spintronics and hydrogen adsorption applications.