Pristine Boron Nitride Nanotubes Research Articles

A DFT study on carbon-doping at different sites of (8, 0) boron nitride nanotube

A density functional theory study is carried out to investigate the geometries and electronic structure of pristine and carbon-doped (8, 0) single-walled boron nitride nanotubes (BNNTs). In order to understand the effect of impurities or doping on (8, 0) single-walled BNNT, we simulated C-doping in six different ways. Geometry optimizations reveal that in the considered models, B–N bond lengths are not significantly influenced by C-doping. Based on the quantum theory of atoms in molecules analysis, charge density accumulation for axial B–N bond critical points (BCPs) of pristine BNNT is slightly larger than zigzag ones. However, due to C-doping at the B- or N-tips, the evaluated electron density tends to decrease slightly at both axial and zigzag B–N BCPs. Besides, results indicate that influence of C-doping on properties of the (8, 0) BNNT could be also detected by values of chemical shielding isotropy (σ iso) and anisotropy (Δσ).

Phenol adsorption study on pristine, Ga-, and In-doped (4,4) armchair single-walled boron nitride nanotubes

Density functional theory (DFT) calculations at the B3LYP/6-31G* level were performed to investigate the adsorption of phenol on the pristine, Ga-, and In-doped (4,4) armchair single-walled boron nitride nanotubes (BNNTs). In comparison with the weak physical adsorption on the pristine BNNT, the hydroxyl group of phenol can lead to significant absorption on the BNNTs, thus suggesting a means for phenol storage. Binding energies corresponding to adsorption of phenol on the Ga and In sites in the model nanotubes was calculated to be −1.18 and −0.93eV, respectively, and about 0.11 and 0.17 electron are transferred from phenol to the model nanotubes. In addition, the value for the fractional number of electrons transferred is negative, indicating that phenol acts as an electron donor. Frontier molecular orbital theory (FMO) and structural analyses show that the low energy level of the LUMO, high polar surface bonds, and large bond lengths of the Ga and In-doped (4,4) BNNT surfaces increase the adsorption of phenol on the model nanotubes.

Detection of phosgene by Sc-doped BN nanotubes: A DFT study

Exploring a novel sensor for detection of toxic phosgene molecules, interaction of pristine and Sc-doped boron nitride nanotubes (BNNT) with the phosgene was investigated using density functional theory calculations in terms of Gibbs free energies, enthalpy changes, geometry, vibrational frequency, work function, and density of state analysis. It was found that unlike the pristine BNNTs, Sc-doped tubes can effectively interact with the phosgene molecule, so that their electronic properties and work functions are dramatically changed upon exposure to this molecule. We believe that doping the BNNTs with Sc may be a good strategy for improving the sensitivity of these tubes towards phosgene, which cannot be trapped and detected by the pristine BNNT.

Retracted: Computational study of hydrogen adsorption on potassium-decorated boron nitride nanotubes

We have investigated the potassium-decorated boron nitride nanotubes for hydrogen storage using semi-empirical AM1 method. The ultra narrow (3,3) and (5,0) boron nitride nanotubes of same diameter but of different chirality have been used. Both of them show hydrogen storage greater than 8 % by weight. Density of states have been calculated, and it is found that the presence of alpha density of state of potassium results in smaller energy gap; as a result of which, the conductivity of the potassium-decorated boron nitride nanotubes is enhanced as compared to pristine boron nitride nanotubes. Charge decomposition analysis showed that there is significant transfer of charge from adsorbate potassium to boron nitride nanotubes; the same is also confirmed by Mulliken population analysis. For same diameter, due to different electronic configuration, zigzag tube is found to be slightly more favorable for hydrogen adsorption. The results of the present simulation study suggest that the potassiumdecorated boron nitride nanotubes are good candidate for hydrogen adsorption.

Boron nitride nanotubes and their functionalization via quinuclidine-3-thiol with gold nanoparticles for the development and enhancement of the HPLC performance of HPLC monolithic columns

In this paper, a new and effective method was described for attaching gold nanoparticles (Au-NPs) on to the surface of thiol-terminated Boron Nitride Nanotubes (BNNT) functionalized with quinuclidine-3-thiol, acting as a bridging agent. The quinuclidine-3-thiol was first grafted onto the surface of the BNNTs via strong interactions between the electron pair from the nitrogen atom of the quinuclidine structure and the electronic gap from the boron atom of the BNNT. The bare surface of Au-NPs facilitates to attach on the thiol group of the thiol-terminated BNNTs. These two nanomaterials (pristine BNNTs and Au-BNNTs) were then incorporated into a monolithic polymer. The obtained monolithic BNNT and AuBNNT stationary phases were very useful columns for the HPLC isocratic mode separation of a series of benzene and naphtalene derivatives. The retention on these two stationary phases was due to the different intermolecular interactions including the dispersion interaction (area of the delocalized π bond), the dipole–dipole interactions, and the electrostatic repulsion. The presence of Au-NPs on the BNNT surface improved significantly the retention and column efficiency for compounds with thiol groups in their structure. As well, it was shown that both retention and column efficiency linearly increased with the nanotube (NT) amount in the polymerization mixture. This manuscript thus established for the first time the fact that BNNT was a very useful nanomaterial for the development of novel HPLC stationary phases and increased the performance of classical equivalent C18 monolithic columns.

Structural and electronic properties of sulphur-doped boron nitride nanotubes

First-principles calculations based on density functional theory were performed to study the structural and electronic properties of sulphur substitution-doped boron nitride (BN) nanotubes, using the theory as implemented in SIESTA code, which uses non-conserving pseudo-potentials in fully non-local form and atomic orbitals as the basis set. The generalized gradient approximation (GGA) was used for the exchange–correlation (XC) potential. The tube selected was a (10, 0) BN nanotube that fell in the range of energy gap independent of the tube diameter. The electronic and structural properties for sulphur substitution in the boron and the nitrogen sites were studied. The structural arrangement in equilibrium conditions for S shows an outward radial deformation around the sulphur atom in the tube. The bandgap of the pristine BN nanotubes was found to be significantly modified on doping.

Quantum molecular descriptors and adsorption properties of SCN− on (6,0), (7,0), (8,0), and Ga-doped (6,0) zigzag single-walled boron nitride nanotubes: a computational study

The behavior of the thiocyanate anion (SCN−) adsorbed on the external surface of H-capped (6,0), (7,0), (8,0), and Ga-doped (6,0) zigzag single-walled boron nitride nanotubes was studied by using density functional calculations. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 suite of programs. We present the nature of the SCN− interaction in selected sites of the nanotubes. Our results show that the pristine boron nitride nanotubes cannot significantly detect SCN−. The calculated binding energy of the Ga-doped (6,0) single-walled boron nitride nanotube indicated that SCN− can be absorbed significantly on the Ga site and these nanotubes can therefore be used for SCN− storage. Binding energy corresponding to adsorption of SCN− on the Ga site in the Ga-doped (6,0) single-walled boron nitride nanotube was calculated to be −263.3 kJ mol−1. The calculated binding energies for SCN− in N-down orientation are higher than those in S-down orientation for all of the configurations. Also, we showed that the nanotube diameter has no significant role in determining the binding energy of SCN− and only the orientation and location of the SCN− and also doping of nanotubes by other atoms play an important role in determining the binding energy. The decrease in global hardness, energy gap, and ionization potential due to SCN− adsorption leads to a the lowering of stability and increase in reactivity of the (6,0) zigzag SCN−– and Ga-doped (6,0) zigzag SCN−–boron nitride nanotube complexes.

Novel polymer nanocomposites from bioinspired green aqueous functionalization of BNNTs

Boron nitride nanotubes (BNNTs) are excellent nanofillers to enhance the mechanical and thermal properties of polymer nanocomposites. Despite the rapid progress in the effective syntheses of BNNTs, the ease of processability and solubility are major roadblocks for their widespread applications. The present work reports for the first time: a facile and environment-friendly green approach for aqueous bioinspired functionalization of boron nitride nanotubes through the use of dopamine, a synthetic mimic of mussel adhesive proteins. This approach is based on the affinity of the amino group of dopamine molecules for the boron atoms in BNNTs and π–π interactions as well as van der Waals interactions between the BNNTs network and dopamine molecules. Functionalization of the boron nitride nanotubes was evidently found to be associated with the existing π–π bonding and van der Waals interactions at the BNNT surfaces, involving the aromatic core structures of the dopamine molecules based on various characterizations. The resultant functionalized BNNTs are highly dispersible in water and a number of solvents. Polymer nanocomposites were prepared using pristine and dopamine functionalized BNNTs as reinforcement in a poly(vinyl difluoroethylene) matrix and tested for the thermal and mechanical properties. The functionalized BNNT reinforced polymer nanocomposites exhibit superior properties as compared to nanocomposites based on pristine BNNTs. This comprehensive study indicates that dopamine functionalized BNNTs are promising materials for various applications and are expected to form the basis of a new class of chemically reactive nanostructures.

Adsorption properties and quantum molecular descriptors of OCN− adsorbed on (6,0), (7,0), and (8,0) zigzag single-walled boron nitride nanotubes: a computational study

Density functional theory (DFT) calculations at the B3LYP/6-31G* level were performed to investigate the adsorbtion properties and quantum molecular descriptors of OCN− adsorbed on the external surface of H-capped (6,0), (7,0), and (8,0) zigzag single-walled boron nitride nanotubes. We present the nature of the OCN− interaction in selected sites of the nanotubes. The chemical reactivity of these compounds was compared using DFT-based descriptors such as global softness, global electrophilicity, electronic chemical potential, global hardness, and electronegativity. Our results show that the pristine boron nitride nanotubes can be used as an OCN− storage medium as long as OCN− is adsorbed on the exterior walls of the nanotubes because of the high binding energy. Binding energy corresponding to adsorption of OCN−on the B site in the (6,0) single-walled boron nitride nanotube was calculated to be −312.3 kJ mol−1. The calculated binding energies for OCN− in N-down orientation are higher than those in O-down orientation for all of the configurations. More efficient binding could not be achieved by increasing the nanotube diameter. Adsorption of OCN− on the (6,0) zigzag boron nitride nanotube model increases the reactivity of the model.

Toxic CO detection by B12N12 nanocluster

We have studied the adsorption of carbon monoxide (CO) on boron nitride nanocluster (B12N12) using density functional theory (DFT) through three different functionals. In contrary to the pristine boron nitride and carbon nanotubes, we found that CO adsorption can induce significant change in the cluster electronic properties, suggesting that B12N12 may be a potential sensor for CO detection. It was also found that the geometry parameters of the obtained structures are not sensitive to the used functional, while the energy values show strong dependency. The results indicated that the most stable configuration of the CO/cluster is a vertical orientation of the CO molecule on B12N12 cluster so that the C atom of CO is close to the B atom of the cluster with adsorption energy of 0.15–0.34eV, based on the three functionals.

Substitutional doping of BN nanotube by transition metal: A density functional theory simulation

Substitution of all 10 3d transition metal (TM) atoms in a [8, 0] zigzag single walled boron nitride nanotube (BNNT) has been investigated with density functional theory based methods. The TM atoms protrude to the exterior of the wall and may facilitate this site to react with an approaching molecular or atomic species. The substitution is site selective when the number of d electrons is less than five with major product of B-substituted BNNT. The substitution produces mixture of B- and N-substituted BNNT when the number of d electrons is larger than five. The doping of TM atoms induces certain impurity states within the band gap of the pristine BNNT, thereby reducing the band gap and affecting the conductivity of metal-doped BNNTs.

Ab initio theoretical study of non-covalent adsorption of aromatic molecules on boron nitride nanotubes

We have studied non-covalent functionalization of boron nitride nanotubes (BNNTs) with benzene molecule and with seven other different heterocyclic aromatic rings (furan, thiophene, pyrrole, pyridine, pyrazine, pyrimidine, and pyridazine, respectively). A hybrid density functional theory (DFT) method with the inclusion of dispersion correction is employed. The structural and electronic properties of the functionalized BNNTs are obtained. The DFT calculation shows that upon adsorption to the BNNT, the center of aromatic rings tend to locate on top of the nitrogen site. The trend of adsorption energy for the aromatic rings on the BNNTs shows marked dependence on different intermolecular interactions, including the dispersion interaction (area of the delocalized π bond), the dipole-dipole interaction (polarization), and the electrostatic repulsion (lone pair electrons). The DFT calculation also shows that non-covalent functionalization of BNNTs with aromatic rings can give rise to new impurity states within the band gap of pristine BNNTs, suggesting possible carrier doping of BNNTs via selective adsorption of aromatic rings.

Density Functional Study of Interaction of Atomic Pt with Pristine and Stone−Wales-Defective Single-Walled Boron Nitride Nanotubes

Interactions between atomic Pt and pristine or Stone−Wales-defective (5,5) single-walled boron nitride nanotubes (BNNTs) were studied using density functional theory (DFT) with truncated nanotube models. The binding energy of Pt on a pristine BNNT is about 20 kcal/mol with little dependency on the binding site. On the other hand, when the Stone−Wales (SW) defect is presented, the atomic Pt is preferentially inserted between the B−B bond in the SW defect region with a large binding energy of 58 kcal/mol. On an SW-defective BNNT, the atomic Pt, even placed away from the defect site, may eventually (thermodynamically) move toward the defect area until being trapped between the B−B bond, and the final adduct has decreased reactivity toward both electrophiles and nucleophiles compared with Pt adsorption to pristine BNNTs. Pt adsorption on pure or SW-defective BNNTs makes the hosting nanotube wide-gap semiconductive by introducing the valence states of the absorbed Pt into the band gap of the nanotube. In compa...

Computations of the quadrupole coupling constants in aluminum doped boron nitride nanotubes

We performed a computational study to calculate the quadrupole coupling constants ( C Q ) in the aluminum doped (Al-doped) boron nitride nanotube (BNNT) based on the density functional theory (DFT). The Al-doped forms of representative (6,0) zigzag and (4,4) armchair models of BNNTs are considered in this study. Comparison with the available data on the pristine BNNTs reveals the influence of Al-doping on the C Q parameters of 11B and 14N atoms in the Al-doped structures. For most lattice sites, the magnitude of influence on the C Q parameters of the zigzag model is larger than that of the armchair model. Similar values of the C Q parameters of 27Al atoms are obtained for the armchair and zigzag BNNTs when the same element is replaced with Al, but the C Q parameter is larger for Al when it forms an Al–B bond than when it forms an Al–N bond.

Theoretical study of physisorption of nucleobases on boron nitride nanotubes: a new classof hybrid nano-biomaterials

We investigate the adsorption of the nucleic acid bases—adenine (A), guanine (G),cytosine (C), thymine (T) and uracil (U)—on the outer wall of a high curvaturesemiconducting single-walled boron nitride nanotube (BNNT) by first-principles densityfunctional theory calculations. The calculated binding energy shows the order:G > A≈C≈T≈U, implying that the interaction strength of the high curvature BNNT with thenucleobases, G being an exception, is nearly the same. A higher binding energy for theG–BNNT conjugate appears to result from hybridization of the molecular orbitals ofG and the BNNT. A smaller energy gap predicted for the G–BNNT conjugaterelative to that of the pristine BNNT may be useful in the application of thisclass of biofunctional materials to the design of next-generation sensing devices.

A theoretical study of silicon-doped boron nitride nanotubes serving as a potentialchemical sensor for hydrogen cyanide

In order to search for a novel sensor to detect and control exposure to hydrogen cyanide(HCN) pollutant molecule in environments, the reactivities of pristine and silicon-doped(Si-doped) (8, 0) single-walled boron nitride nanotubes (BNNTs) towards the HCNmolecule are investigated by performing density functional theory (DFT) calculations. TheHCN molecule presents strong chemisorption on both the silicon-substituted boron defectsite and the silicon-substituted nitrogen defect site of the BNNT, which is insharp contrast to its weak physisorption on pristine BNNT. A remarkable chargetransfer occurs between the HCN molecule and the Si-doped BNNT as proved bythe electronic charge densities. The calculated data for the electronic densityof states (DOSs) further indicate that the doping of the Si atom improves theelectronic transport property of the BNNT, and increases its adsorption sensitivitytowards the HCN molecule. Based on calculated results, the Si-doped BNNTis expected to be a potential resource for detecting the presence of toxic HCN.

Adsorption of formaldehyde molecule on the pristine and silicon-doped boron nitride nanotubes

The adsorption of formaldehyde (HCOH) molecule on the pristine and silicon-doped (Si-doped) single-walled (8, 0) boron nitride nanotubes (BNNTs) is investigated using density functional theory (DFT) calculations. Compared with the weak physisorption on the pristine BNNT, the HCOH molecule presents strong chemisorption on both silicon-substituted boron defect site and silicon-substituted nitrogen defect site of the BNNT, as indicated by the calculated geometrical structures and electronic properties for these systems. It is suggested that the Si-doped BNNT presents high sensitivity to toxic HCOH. Based on calculated results, the Si-doped BNNT is expected to be a potential novel sensor for detecting the presence of HCOH.

Possible Magnetism of Be-Doped Boron Nitride Nanotubes

We studied the electronic and magnetic properties of pristine and Be-doped (5, 5) boron nitride (BN) nanotubes using density functional theory within a generalized gradient approximation. We found that the pristine (5, 5) BN nanotube is an indirect band gap material, which is in agreement with previous findings. Doping with Be induces spontaneous magnetization (approximately 1 microB/Be atom) in the (5, 5) BN nanotube. The defect states are not localized to the Be atoms themselves, but spread out over their neighboring B and N atoms. In particular, the system becomes a half metal when Be is substituted for B.

First-principles study of transport of V doped boron nitride nanotube

We perform first-principles calculations of spin-dependent quantum transport in V doped boron nitride nanotube: the junction of pristine ( 6 , 0 ) boron nitride nanotube in contact with V doped ( 6 , 0 ) boron nitride nanotube electrodes. Large tunnel magnetoresistance and perfect spin filtration effect are obtained. The zero bias tunnel magnetoresistance is found to be several thousand percent, it reduces monotonically to zero with a voltage scale of about 0.65 V, and eventually goes to negative values after the bias of 0.65 V. The ratio of spin injection is above 95% till the bias of 0.85 V and is even as large as 99% for the bias from 0.25 eV to 0.55 eV when the magnetic configurations of two electrodes are parallel. The understanding of the spin-dependent nonequilibrium transport is presented by investigating microscopic details of the transmission coefficients.

Stone−Wales Defects in Single-Walled Boron Nitride Nanotubes: Formation Energies, Electronic Structures, and Reactivity

The geometries, formation energies, electronic properties, and reactivities of Stone−Wales (SW) defects in single-walled (8,0) boron nitride nanotubes (BNNTs) were investigated by means of gradient-corrected density functional theory (DFT) computations. SW defects deform BNNTs severely and result in local curvature changes at defect sites. The energies of defect formation increase with increasing tube diameters and are orientation dependent. Depending on the SW defect orientations, additions to central 7-7 ring fusions can be either more or less favorable than to defect-free sites. The reaction energies of model H2 addition are mostly endothermic for defective as well as pristine BNNTs, but reactions at the most favorable sites near SW defect (homoelement N−N bonds followed by the B−B bond sites) are exothermic. This and the fact that the band structures of BNNTs are only slightly changed by SW and vacancy defects as well as by chemical additions at low modification ratios endow BNNTs with great application potential.