Zigzag Single-walled Boron Nitride Nanotubes Research Articles

Structural, electronic, phonon, and elastic properties of zigzag single-walled and double-walled boron nitride nanotubes

The study used Density Functional Theory to simulate the properties of single-walled and double-walled boron nitride nanotubes. The cohesive energy calculations suggest that double-walled nanotubes are more stable than single-walled nanotubes. Double-walled nanotubes have a narrower bandgap than single-walled nanotubes. The smaller diameter of the nanotubes reduces available energy for vibrational modes. Double-walled nanotubes have larger Young’s modulus, shear modulus, and bulk modulus than single-walled nanotubes. Both single-walled and double-walled nanotubes perform like auxetic materials in some directions. The group velocity of acoustic phonons in SWBNNTs (6, 0) is higher than in SWBNNTs (12, 0).

Axial deformation effects on hydrogen storage of Ni decorated (8,0) zigzag single-walled boron nitride nanotubes: a DFT study

The effect of axial deformation on tuning the hydrogen storage of nickel functionalised (8,0) zigzag boron nitride nanotube is investigated by using density functional theory calculations. The assessment has been carried out based on the adsorption of molecular hydrogen with the binding energy lying in the desirable energy window, charge transfer, the density of states, pairwise and nonpairwise additivty, frontier orbital band gaps, isosurface plots, polarizabilities and hyperpolarizabilities, simulated Infrared (IR) and Raman (R). The numerous changes in adsorption energy of H2 upon relaxation or compression of only (1%) strain points to the sensitivity of H2 binding to axial deformation effects. The calculated pairwise and non-pairwise additive components show that the role of the BNNT is not restricted to support the metal. Spectral analysis additionally as polarizability and hyperpolarizability calculations characterise the relaxed structure (Z = 1.01), that H2 adsorption energy (−0.552 eV) is within the suggested energy vary for hydrogen storage, to be energetically additional desirable than the compressed structure (Z = 0.99). The results provide some way to manage and characterise the hydrogenation process of metal functionalised BNNTs by strain loading.

Potential applications of armchair, zigzag, and chiral boron nitride nanotubes as a drug delivery system: Letrozole anticancer drug encapsulation

A density functional theory calculation has been applied to be investigated the ability of (12,12) armchair, (21,0) zigzag, and (18,5) chiral boron nitride nanotubes (BNNT) as the drug nanocarrier in Letrozole delivery. For this purpose, the behavior of drug Letrozole when encapsulated into different chirality of BNNTs with the same diameter was studied. Moreover, the reduced side effects and increasing solubility of Letrozole can be achieved by encapsulation in boron nitride nanotubes. A complete understanding of the encapsulation process of drug molecules into BNNTs is necessary for the development of drug delivery systems. Geometry optimizations of the three types of BNNTs and drug Letrozole have been performed by means of density functional theory calculation, using the functional wb97xd with 6-31G basis set. The results indicate that Letrozole is encapsulated in cavity of the nanotubes. The structural and the electronic properties of encapsulated Letrozole in the studied systems have been also predicted by quantum mechanical descriptors such as equilibrium distances, highest occupied molecular orbital (HOMO)—lowest unoccupied molecular orbital (LUMO) energy gap. The quantum mechanical calculations verify that the armchair and the chiral single-walled boron nitride nanotubes could spontaneously adsorb Letrozole in a chemisorption process while the physisorption process plays a large role in adsorption within the zigzag single-walled boron nitride nanotube.

Interaction of Au and Boron Nitride Nanotube: A DFT Study

In this work, structural and electronic properties of zigzag single-walled boron nitride nanotube (BNNT) are considered through density functional theory. In order to reduce the large band gap of BNNT, the effects of 2-5 Au atoms are reported as impurities in two different patterns. We selected two dispersions for Au atoms: one for the random dispersion and the other for the chain dispersion. Our results show that the chain modes have lower formation energy and their band gap is smaller, as well. We could tune the large band gap of BNNT from 5.96 eV to 0.41 eV in chain mode. In the random mode, the band gap could reach a minimum level of 1.01 eV.

A DFT study for adsorption of CO on Ni, Pd and Pt atoms doped (7, 0) boron nitride nanotube

ABSTRACTBy using density functional theory calculations, we investigated the structural, electronic and magnetic properties of carbon monoxide (CO) adsorption on the pure, Ni, Pd and Pt doped atoms in zigzag single-walled (7, 0) boron nitride nanotubes (BNNTs). The results indicated that compared to the pure (7, 0) BNNTs, replacing B atom by Ni, Pd and Pt atoms can significantly increase the adsorption energy of CO gas on the BNNTs. The adsorption energies of CO gas on the pure (7, 0) Ni, Pd and Pt doped (7, 0) BNNTs are −0.2013, −1.746, −1.593 and −2.257 eV, respectively. Our results revealed that in comparison with the pure (7, 0) BNNTs, CO gas is chemisorbed on the transition metal doped (7, 0) BNNTs with the appreciable adsorption energy. In addition, it was found that by doping these atoms, band gap energy of the pure (7, 0) BNNTs is considerably decreased. These observations suggested that the Pt doped (7, 0) BNNTs can be introduced as a promising candidate in gas sensor devices for detecting CO gas.

Non-covalent green functionalization of boron nitride nanotubes with tunable aryl alkyl ionic liquids: A quantum chemical approach

The quantum mechanical treatments of the non-covalent interactions of the (8,0) zigzag single-walled boron nitride nanotube (BNNT) with the five types tunable aryl alkyl ionic liquids (TAAILs) as well as corresponding cations were carried out at the M06-2X/6–31+G(d):PM6 level of theory to better understand the trends in interaction between BNNT and ILs. Two different complexes (A|| and B⊥) were found in non-covalent interaction between BNNT surface and [X-PhMIM][BF4] (XNH2, CH3, H, CHO and NO2) TAAILs. Comparison of interaction energies indicates that the B⊥ complexes are more stable than A|| ones. A detailed analysis of the geometric and electronic properties, charge transfer, electron density properties, global reactivity descriptors, work function, dipole moment and electron density of the states for pure BNNT and different configurations of the modified BNNT were carried out. It is predicted that the π-π stacking of BNNT with the TAAILs is accompanied by a decrease in the energy gap. ChelpG analysis reveals that the interaction of ILs with BNNT induces the charge transfer from anion to cation. Inspection of the results shows that the charge in the A|| complexes is transferred from IL to BNNT for electron donating substituents and from BNNT to IL for H and electron accepting ones. The results also show that the charge in the B⊥ complexes is transferred from IL to BNNT with the exception of IL containing the NO2 substituent. To understand the behavior of non-covalent interactions (NCI) between BNNT sidewalls and Z1–5 TAAILs and the corresponding Z′1–5 cations, the NCI index (RDG) is utilized.

Influence of Defects in Boron Nitride Nanotubes in the Adsorption of Molecules. Insights from B3LYP-D2* Periodic Simulations

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.

CO2 adsorption on single-walled boron nitride nanotubes containing vacancy defects

The adsorption of a CO2 molecule on the vacancy defect type of armchair (5,5) and zigzag (10,0) single-walled boron nitride nanotubes was studied based on Density Functional Theory (DFT).

Interaction of vitamins A, B1, C, B3 and D with zigzag and armchair boron nitride nanotubes: A DFT study

In this work, based on the density functional theory, the interaction of vitamins A, B1, C, B3 and D with (5, 5) armchair and (9, 0) zigzag single-walled boron nitride nanotubes (BNNTs) are studied. It is found that binding of vitamins A, B1, C, B3 and D with (9, 0) and (5, 5) BNNTs is thermodynamically favorable. Calculated solvation energies show that the solubility of functionalized (9, 0) BNNTs is higher than that of functionalized (5, 5) BNNT, and both dissolutions in water are spontaneous. The results showed that BNNTs can act as a suitable drug delivery vehicle for vitamins A, B1, C, B3 and D within biological systems. This study may provide a new insight into the development of the functionalized boron nitride nanotubes as drug delivery systems for virtual applications.

Effect of the Stone–Wales (SW) defect on the response of BNNT to axial tension and compression: a quantum chemical study

Using density functional theory, effect of the Stone–Wales (SW) defect on the structural and electronic properties of (6,0) zigzag single-walled boron nitride nanotube (BNNT) under axial tension and compression was investigated at B3LYP/6-31+G(d) level of theory. The calculated binding energy for SW defective BNNT is estimated to be smaller than pristine BNNT. In Stone–Wales defected BNNT (SW–BNNT), the defect region serves as a nucleation site for fraction. It is predicted that the fracture is started from the N–N bond connecting the pentagon and heptagon rings, which is different from fracture mechanism proposed for carbon nanotubes (CNT) with similar location of SW defects. Increase in the energy difference between defective and perfect BNNT, ∆E = E SW − E perfect, was predicted upon axial tension. According to our calculation, band gap energy of the SW–BNNT decreases under axial tension and increases under axial compression. It is predicted that the SW–BNNT and in turn its tensile form are more suitable than perfect one for photoconductivity applications.

Gas-Phase and Microsolvated Glycine Interacting with Boron Nitride Nanotubes. A B3LYP-D2* Periodic Study

The adsorption of glycine (Gly) both in gas-phase conditions and in a microsolvated state on a series of zig-zag (n,0) single-walled boron nitride nanotubes (BNNTs, n = 4, 6, 9 and 15) has been studied by means of B3LYP-D2* periodic calculations. Gas-phase Gly is found to be chemisorbed on the (4,0), (6,0) and (9,0) BNNTs by means of a dative interaction between the NH2 group of Gly and a B atom of the BNNTs, whose computed adsorption energies are gradually decreased by increasing the tube radius. On the (15,0) BNNT, Gly is found to be physisorbed with an adsorption driving force mainly dictated by p-stacking dispersion interactions. Gly adsorption in a microsolvated environment has been studied in the presence of seven water molecules by progressively microsolvating the dry Gly/BNNT interface. The most stable structures on the (6,0), (9,0) and (15,0) BNNTs present the Gly/BNNT interface fully bridged by the water solvent molecules; i.e., no direct contact between Gly and the BNNTs takes place, whereas on the (4,0) BNNT the most stable structure presents a unique direct interaction between the COO− Gly group and a B atom of the nanotube. Further energetic analyses indicate that the (6,0), (9,0) and (15,0) BNNTs exhibit a low water affinity, which favors the Gly/water interactions upon BNNT coadsorption. In contrast, the (4,0) BNNT has been found to show a large water affinity, bringing the replacement of adsorbed water by a microsolvated glycine molecule as an unfavorable process.

Methane storage on aluminum-doped single wall BNNTs

• Al-doped BNNTs with N atoms replaced by Al can be treated as a good medium for storage and also a sensor for methane detection. • Each Al-site is only able to absorb one CH 4 molecule. • At low concentration of Al atoms in the surface of BNNTs, the adsorption and gas sensor properties of the Al-doped BNNTs with respect to CH 4 remain unchanged. Adsorption of methane (CH 4 ) on inside and outside of aluminum-doped (Al-doped) zigzag single-walled boron nitride nanotubes, BNNTs/Al, has been studied using density-functional theory (DFT) method. The effect of diameter and type of atom of BNNT replaced by the Al atom on the adsorption properties of CH 4 were investigated. Our results indicate that, compared to pristine BNNTs, replacing both B atom by Al, BNNT/Al(B) and N atom by Al, BNNT/Al(N), can notably enhance the binding energy of CH 4 on BNNTs and the latter case has been more superior. The average binding energy for the most stable configuration of CH 4 on BNNTs/Al(N) and BNNTs/Al(B) are about −26.12 and −16.53 kJ mol −1 , respectively, which are typical for the physisorption and suitable for technical applications. The results show that while the geometry of BNNT/Al(N or B)–CH 4 complexes is determined by weak electrostatic forces, the binding energy mainly determines by dispersion forces. For all complexes, the energy gaps, natural bond orbital (NBO) analysis, dipole moments, natural charge and density of state (DOS) diagrams were extracted. Finally, the applicability of BNNTs/Al(N) both as a medium for storage and gas sensor for methane detection were confirmed.

Electronic and structural properties of Au-doped zigzag boron nitride nanotubes: A DFT study

In this paper, structural and electronic properties of zigzag single-walled boron nitride nanotubes are investigated within density functional theory by adding one gold atom as an impurity. One boron and one nitrogen atoms are substituted by one gold atom separately. Calculations show that the substitution of Au atom on boron atom turns the BNNT into a p-type semiconductor with a band gap of 2.435eV. On the other hand, doping the Au atom on N site diminishes the pristine BNNT gap to 3.905eV.

Theoretical study on adsorption and dissociation of NO2 molecules on BNNT surface

The adsorption of NO2 molecules on (8,0) zigzag single-walled boron nitride nanotube surface is investigated using density functional theory calculations. Two interaction modes, nitro (interacting atom is N) and nitrite (O interacts with BNNT) have been studied with increase in number of NO2 molecules. The adsorption of single NO2 molecule in both configurations is observed to be exothermic and physical in nature. However, in nitrite configuration, NO2 molecules are chemisorbed on the surface leading to the dissociation of NO2 molecules into NO and O. The density of states, natural bond orbital analysis and frontier orbital pictures provide rational understanding of the charge transfer involved in the process and predict significant enhancement in the conductivity of the BNNT after NO2 adsorption. The DFT calculations show that NO2 adsorption introduces new impurity states in the band gap of bare BNNT and expand their applications as NO2 molecule gas sensor and catalytic surface for NO dissociation depending upon the mode of adsorption.

DFT studies of functionalized zigzag and armchair boron nitride nanotubes as nanovectors for drug delivery of collagen amino acids

The interaction of collagen amino acids with (5, 5) armchair and (9, 0) zigzag single-walled boron nitride nanotubes (BNNTs) are studied using density functional theory. Our results show that the BNNTs can act as a suitable drug delivery vehicle of collagen amino acids within biological systems. DFT-LDA/DNP calculations revealed that the binding and solvation energies were negative for (5, 5)/(9, 0) BNNTs–collagen amino acid complexes implying the thermodynamic favorability and spontaneous interactions of collagen amino acids with BNNTs sidewall. These results were extremely relevant in order to identify the potential applications of functionalized BNNTs as drug delivery systems.

Vibrational and electronic properties of single-walled and double-walled boron nitride nanotubes

We calculated IR, nonresonance Raman spectra and vertical electronic transitions of the zigzag single-walled and double-walled boron nitride nanotubes ((0,n)-SWBNNTs and (0,n)@(0,2n)-DWBNNTs). In the low frequency range below 600cm−1, the calculated Raman spectra of the nanotubes showed that RBMs (radial breathing modes) are strongly diameter-dependent, and in addition the RBMs of the DWBNNTs are blue-shifted reference to their corresponding one in the Raman spectra of the isolated (0,n)-SWBNNTs. In the high frequency range above ∼1200cm−1, two proximate Raman features with symmetries of the A1g (∼1355±10cm−1) and E2g (∼1330±25cm−1) first increase in frequency then approach a constant value of ∼1365 and ∼1356cm−1, respectively, with increasing tubes’ diameter, which is in excellent agreement with experimental observations. The calculated IR spectra exhibited IR features in the range of 1200–1550cm−1 and in mid-frequency region are consistent with experiments. The calculated dipole allowed singlet–singlet and triplet–triplet electronic transitions suggesting a charge transfer process between the outer- and inner-shells of the DWBNNTs as well as, upon irradiation, the possibility of a system that can undergo internal conversion (IC) and intersystem crossing (ISC) processes, besides the photochemical and other photophysical processes.

Physisorption vs. chemisorption of probe molecules on boron nitride nanomaterials: the effect of surface curvature

The adsorption of H2O, NH3 and HCOOH as polar probe molecules and C6H6 and CH4 as non-polar ones on a series of zig-zag (n,0) single-walled boron nitride nanotubes (BNNTs) and on a boron-nitride mono-layer (BNML) has been studied by means of B3LYP-D* periodic calculations. Computed electrostatic potential maps for the pristine BN nanomaterials indicate that the smaller the radius, the larger the polar character. Polar molecules are found to be strongly chemisorbed on small radius BNNTs by means of dative interactions between electron donor atoms of the molecules and B atoms of the BNNTs, H-bonding, as well as dispersive forces. Remarkably, for HCOOH interacting with the (4,0) BNNT, this dative interaction is accompanied by a proton transfer to the nanotube. The corresponding computed adsorption energies decrease sharply with increasing tube radius, gradually approaching the values for physisorption on the BNML. Adsorption of non-polar molecules, mainly dictated by π-stacking (C6H6) and CH-π (CH4) dispersion interactions, is found to be energetically more favorable when physisorbed on large radius BNNTs, the most stable adducts being formed on the BNML.

Theoretical Study of Thiazole Adsorption on the (6,0) zigzag Single-Walled Boron Nitride Nanotube

The interaction of thiazole drug with (6,0) zigzag single-walled boron nitride nanotube of finite length in gas and solvent phases was studied by means of density functional theory (DFT) calculations. In both phases, the binding energy is negative and presenting characterizes an exothermic process. Also, the binding energy in solvent phase is more than that the gas phase. Binding energy corresponding to adsorption of thiazole on the BNNT model in the gas and solvent phases was calculated to be -0.34 and -0.56 eV, and about 0.04 and 0.06 electrons is transferred from the thiazole to the nanotube in the phases. The significantly changes in binding energies and energy gap values by the thiazole adsorption, shows the high sensitivity of the electronic properties of BNNT towards the adsorption of the thiazole molecule. Frontier molecular orbital theory (FMO) and structural analyses show that the low energy level of LUMO, electron density, and length of the surrounding bonds of adsorbing atoms help to the thiazole adsorption on the nanotube. Decrease in global hardness, energy gap and ionization potential is due to the adsorption of the thiazole, and consequently, in the both phases, stability of the thiazole-attached (6,0) BNNT model is decreased and its reactivity increased. Presence of polar solvent increases the electron donor of the thiazole and the electrophilicity of the complex. This study may provide new insight to the development of functionalized boron nitride nanotubes as drug delivery systems for virtual applications.

Adsorption and Electronic Structure Study of Imidazole on (6,0) Zigzag Single-Walled Boron Nitride Nanotube

AbstractThe behavior of the imidazole adsorbed on the external surface of H-capped (6,0) zigzag single-walled boron nitride nanotube as a functional group was studied by using density functional calculations in gas and solvent phases. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using a locally modified version of the GAMESS electronic structure program. Our results show that the pristine boron nitride nanotubes can significantly detect the imidazole. In both phases, the binding energy for the imidazole/BNNT complex is negative and presenting characterizes an exothermic process. The increase in global hardness and energy gap due to imidazole adsorption lead to an increasing of the stability and decrease in reactivity of the complex in the both phases. Also, presence of polar solvent increases the electron donor of imidazole and electrophilicity of the nanotube. This study may provide new insight to the development of functionalized boron nitride nanotubes as drug delivery systems for virtual applications.Graphical AbstractGraphics for use in the table of contents. [IMAGE]

Ab initio investigation of the SCN− chemisorption of single-walled boron nitride nanotubes

The thiocyanate anion (SCN−) adsorption capacity of zigzag single-walled boron nitride nanotubes (SWBNNTs) is studied via first-principles theory. Binding energy corresponding to the most stable configuration of SCN−/BNNT is found to be −148.42kJmol−1, which is typical for the chemisorptions. Our results indicate that both aluminum and gallium doping can significantly enhance the adsorption energy of SCN−/BNNTs complexes. Our electronic results reveal that there is a significant orbital hybridization between two species in adsorption process being an evidence of strong interaction. Thus, we arrive at the prediction that the BNNTs nanocage can be implemented as suitable sensor for practical applications.