Surface Of Boron Nitride Nanotubes Research Articles

Zigzag boron nitride nanotube functionalization as a sensor for the recognition of group IIA (Mg2+, Ca2+) metal ions, quasi-metal (Si2+, Ge2+) ions, and transition metal (Cu2+, Zn2+) ions: a computational study.

Boron nitride nanotubes (BNNTs) provide an exceptional and sophisticated platform for detecting metal ions with high surface area and remarkable chemical stability. Metal cations tend to bind to the surface of BNNTs, which leads to significant changes in the electrical properties of nanotubes. BNNT-based metal ion sensors have shown promising results in various applications, including water quality monitoring, biomedical research, industrial quality control, and environmental monitoring. In the present study, we have explored the electronic sensitivity of the BNNT to metal ions (Si2+, Ge2+, Cu2+, Zn2+, Mg2+, and Ca2+). The interaction between the ions with the pristine BNNT is performed in the solution phase. The results show that ion adsorption on the nanotube surface is exothermic and favorable. The density of states calculation is presented to investigate the electronic properties of the nanotube during the adsorption process. The results display that an increase in the electrical conductivity of the complexes accompanies the reduction in the energy gap. Based on the obtained data, the Si2+ and Ge2+ cations adsorbed on the BNNT with satisfactory Eg changes (%ΔE) can be promising candidates for better sensing ability. All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-31G(d,p) basis set. The present approach incorporates the utilization of empirical atom-atom dispersion in conjunction with long-range correction. The calculations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView 6.0.16 program.

Preparations and Thermal Properties of PDMS-AlN-Al2O3 Composites through the Incorporation of Poly(Catechol-Amine)-Modified Boron Nitride Nanotubes

As one of the emerging nanomaterials, boron nitride nanotubes (BNNTs) provide promising opportunities for diverse applications due to their unique properties, such as high thermal conductivity, immense inertness, and high-temperature durability, while the instability of BNNTs due to their high surface induces agglomerates susceptible to the loss of their advantages. Therefore, the proper functionalization of BNNTs is crucial to highlight their fundamental characteristics. Herein, a simplistic low-cost approach of BNNT surface modification through catechol-polyamine (CAPA) interfacial polymerization is postulated to improve its dispersibility on the polymeric matrix. The modified BNNT was assimilated as a filler additive with AlN/Al2O3 filling materials in a PDMS polymeric matrix to prepare a thermal interface material (TIM). The resulting composite exhibits a heightened isotropic thermal conductivity of 8.10 W/mK, which is a ~47.27% increase compared to pristine composite 5.50 W/mK, and this can be ascribed to the improved BNNT dispersion forming interconnected phonon pathways and the thermal interface resistance reduction due to its augmented compatibility with the polymeric matrix. Moreover, the fabricated composite manifests a fire resistance improvement of ~10% in LOI relative to the neat composite sample, which can be correlated to the thermal stability shift in the TGA and DTA data. An enhancement in thermal permanence is stipulated due to a melting point (Tm) shift of ∼38.5 °C upon the integration of BNNT-CAPA. This improvement can be associated with the good distribution and adhesion of BNNT-CAPA in the polymeric matrix, integrated with its inherent thermal stability, good charring capability, and free radical scavenging effect due to the presence of CAPA on its surface. This study offers new insights into BNNT utilization and its corresponding incorporation into the polymeric matrix, which provides a prospective direction in the preparation of multifunctional materials for electric devices.

Synergistic effect on dispersion, thermal conductivity and mechanical performance of pyrene modified boron nitride nanotubes with Al2O3/epoxy composites

Due to the intrinsic attributes of boron nitride nanotubes (BNNT), its assimilation into composite materials displays an immense potential for thermal performance augmentation. However, the presence of Van der Waals forces and hydrophobicity of BNNT causing interfacial incompatibility with the polymeric matrix greatly hinders its practical applications. This instigates a dispersion dilemma and subsequent agglomeration of BNNT in the polymer matrix, which massively hampers the thermal performance of the polymer composites. In this respect, we here present a facile BNNT modification strategy; deposition of amine-attached pyrene (PAA) on the BNNT surface through a mild sonication process. The presence of amine in the pyrene molecules reduces the surface tension of PAA deposited BNNT (BNNT-PAA) allowing it to be readily dispersed in the various solvents even at the high concentrations. BNNT-PAA was added as a co-filler along with a primary filler (Al2O3) in the epoxy resin. The formed epoxy composites presented an improvement of as much as 33.1 % in tensile strain and 175.8 % in tensile stress with the addition of 1wt% of BNNT-PAA, while the thermal conductivity of vertical direction was enhanced as high as 62.3 %, possibly due to the constructed BNNT thermal conducting channels among alumina particles.

Surface structure design of boron nitride nanotubes and mechanism of their regulation on properties of epoxy composite dielectric

Adding nanofillers into epoxy resin matrices is a common method to achieve their multi-function. Boron nitride nanotubes (BNNTs) with one-dimensional nanostructures have attracted much attention because of their ultra-high thermal conductivity, wide energy level band gap, high aspect ratio and mechanical strength. Yet, the strong π-π non-covalent bonding and lip-lip interactions make BNNTs prone to agglomeration in the epoxy resin matrix. Moreover, the different physicochemical properties of BNNTs and epoxy resins as well as the chemical inertness of BNNTs surface lead to the lack of effective interfacial interaction between BNNTs and epoxy resin matrix. Therefore, the performance of the epoxy composite dielectric is not enhanced by simple blending solely, but will even have the opposite effect. To address the problems of BNNTs, in this study, the surface structure of BNNTs is constructed from the perspective of interface modulation by using sol-gel method to coat mesoporous silica (mSiO<sub>2</sub>) on BNNTs’ surface and further introducing silane coupling agent (KH560). The results indicate that the surface structure of BNNTs can optimize the level of interfacial interaction between BNNTs and epoxy resin matrix, which leads to stronger interfacial connection and elimination of internal pore phenomenon. The dielectric constant and loss of the composite dielectric prepared in this way are further reduced, reaching 4.1 and 0.005 respectively at power frequency, which is significantly lower than that of pure epoxy resin. At the same time, the mechanical toughness (3.01 MJ/m<sup>3</sup>) and thermal conductivity (0.34 W/(m⋅K)) are greatly improved compared with the counterparts of pure epoxy resin. In addition, the unique nano-mesoporous structure of mSiO<sub>2</sub> endows the composite dielectric with a large number of deep traps, which effectively hinders the migration of electrons, thereby improving the electrical strength of the composite dielectric, and the breakdown field strength reaches 95.42 kV/mm. Furthermore, the interfacial mechanism of BNNTs’ surface structure on dielectric relaxation and trap distribution of composite dielectrics is systematically studied by Tanaka multinuclear model. The above results indicate that the good interfacial interaction between BNNTs and epoxy resin matrix is crucial in establishing the micro-interface structure and improving the macroscopic properties of composite dielectrics. This study presents a novel idea for the multifunctionalities of epoxy resin, and also provides some experimental data support for revealing the correlation among surface properties of nano-fillers, microstructure and macroscopic properties of composite dielectric.

Effect of Ge-doping on the adsorption of anions (F−, Cl−, Br−) onto the outer surface of boron nitride nanotube: a DFT study

Effect of Ge-doping on the adsorption of anions (F−, Cl−, Br−) onto the outer surface of boron nitride nanotube: a DFT study

Ibuprofen adsorption and detection of pristine, Fe–, Ni–, and Pt–doped boron nitride nanotubes: A DFT investigation

The main challenge has been focused on ibuprofen drug detection and adsorption of boron nitride nanotube (BNNT) doping with transition metal (TM = Fe, Ni, and Pt) atoms using the density functional theory calculation in gas and water phases. The geometrical structures, adsorption energies, solvation energies, and electronic properties were examined. The optimized geometries show that the ibuprofen molecule oriented itself at different bond distances and angles with respect to BNNT surface. The calculated results display exothermic adsorption processes for all ibuprofen/BNNT and ibuprofen/TM–doped BNNT complexes. Ibuprofen molecule can absorb on the Fe–, Ni–, and Pt–doped BNNTs via a stronger interaction than those of pristine BNNT in both gas and water phases in which the Fe doping on N site of BNNT shows the strongest interaction with ibuprofen molecule. The H (head) site of ibuprofen molecule to BNNT surface shows stronger interaction than M (middle) and T (tail) sites. The short of adsorption distance and the large of charge transfer correspond to the high adsorption strength of TM–doped BNNTs toward ibuprofen molecule. Charge analysis confirms the partial charge transfer occurring from the ibuprofen molecule to the BNNTs. The solvation energies in water solution reveal that the ibuprofen molecule adsorbed on TM–doped BNNTs is more soluble than pristine BNNT. The work functions of BNNTs are reduced by ibuprofen adsorption. A short recovery times and suitable desorption temperatures are observed for the ibuprofen desorption on pristine BNNT and TM–doped BNNT surfaces. After ibuprofen adsorption, the energy levels and energy gaps of Fe–, Ni–, and Pt–doped BNNTs are changed in which Ni doping on B atom of BNNT displays the largest change. The quantum molecular characteristics of BNNT will be changed after ibuprofen adsorption. The orbital distributions are occurred around the ibuprofen molecule and doping site. The alteration in the density of states for TM–doped BNNT is considerably more pronounced compared to the pristine BNNT. Drawing from the achieved outcomes, it can be inferred that when employed for the delivery of ibuprofen in biological media, Fe–, Ni–, and Pt–doped BNNTs exhibits the greater suitability for the adsorption and detection of the ibuprofen molecule compared to pristine BNNT.

Chemical modifications of boron nitride nanotubes with heterocyclic molecules: A DFT study

The density functionals M06–2X and B3LYP were exploited for investigating the impact of modifying the surface of a boron nitride nano-tube (BNNT) with the furan molecule in terms of energy, electronics, and geometry. According to the density functional theory (DFT) results, BNNT had a strong interaction with the furan molecule. So, the adhesion of the furan molecule onto the surface of BNNT was consistent with the chemical functionalization. Furthermore, the computed density of states indicated that the electronic features of the BNNT were adjusted with a partial chemical modification. Also, the functional energy raised by enhancing the electron donation property of the functional groups, which was due to the rise in the electrical conductance of BNNT in contrast with the pristine BNNT. Retaining the electronic features of BNNT and the increased solubility demonstrated that using furan to chemically modify BNNTs could be a useful method to purify them.

Palladium nanoparticle formation on boron nitride nanotubes and their photocatalytic performance with visible light

Development of efficient but long-term stable photocatalysts for removal of organic pollutants from water sources is still a huge challenge up to date. In this study, palladium nanoparticles (Pd NPs) were dispersed on the surface of boron nitride nanotube (BNNT), a series of Pd@BNNT hybrid was synthesized using a one-step and cost-effective ultrasonication method, and the photocatalytic performance were investigated. By increasing the ultrasonication time, productivity of the Pd NPs on BNNT was increased and also obtained the uniform nanostructure, thereby enhancing the specific surface area, which is the promising attribute for the efficient removal of organic pollutants. In this regard, the Pd@BNNT3 hybrid shows higher photocatalytic performance with respect to other catalysts against the crystal violet and levofloxacin, 97.6%/50 min, and 97.7%/40 min respectively. Further, a reusability test was conducted for the Pd@BNNT3 hybrid by using the CV over seven consecutive cycles. Approximately, 24.7% photocatalytic efficiency was lost in the final catalytic activity owing to its particle loss (7.2%). Significantly, the structure of the Pd@BNNT3 catalyst did not change even after measuring the reusability seven times, suggesting that the catalyst has a stable morphology. The enhanced photocatalytic performance is attributed to the larger specific surface area (128 m2/g) of Pd@BNNT3 hybrid, which enhance the production of the visible light induced radical oxygen species. As a summary, the efficient photocatalyst developed in this study can eliminating the organic contaminants from the wastewater source and is a highly promising solution for tackling wastewater treatment challenges in the near future.

State-of-the-art predictive modeling of heavy metal ions removal from the water environment using nanotubes

In this research, molecular dynamics (MD) simulation is used to investigate the efficiency of carbon nanotubes (CNT) and boron nitride nanotubes (BNNT) in removing lead ions from contaminated waters. Then the effect of functionalizing nanotubes with –COO– and COOH– functional groups and the nanotubes’ absorption performance of two different concentrations of lead ions are studied. To better evaluate adsorption process, the set of descriptors, such as interaction energies, radial distribution function, etc., are calculated. The MD results show that the absorption performance is significantly improved by modifying the surface of CNT and BNNT with functional groups. In addition, the adsorption capacity increases in higher concentrations of Pb ions at BNNTCOO– and CNTCOOH systems. The interaction energy of BNNTCOO– with a concentration of 50 lead ions is − 2879.28 kJ/mol, which is about 106 kJ/mol more negative than BNNTCOO– at a concentration of 20 lead ions. Also, it is observed that the functionalization of both nanotubes with –COO– increases their absorption capacity. The obtained results from this study provide significant information about the mechanisms of lead adsorption on the surface of nanotubes.

Analysis of surface deviation impact on bio-mass sensing application of Boron Nitride Nanotubes

The Boron Nitride Nanotube (BNNT) is capable of sensing the masses even below the zeptogram level when it is used as a resonator. The surface of BNNT is considered to be straight in most of the existing literatures. In this work, wavy surface of BNNT is considered, and its effect on the mass sensing capabilities of BNNT is investigated. A nonlinear mathematical model is developed by applying the continuum mechanics approach on surface deviated (wavy) BNNT of a hollow cylindrical geometry with thin wall. The model is normalized to the nanoscale level, and the degrees of nonlinearity arise due to waviness are identified in BNNT mass sensing application. The deformation in nanostructures is nonlinear that causes oscillations of large amplitude. The midplane stretching and waviness factor of a single walled BNNT, which is clamped at both of its end, are considered to investigate its frequency response to the attached mass. It is proposed to include waviness surface of BNNT to develop more accurate biomass sensor. It is further found that there is a shift in the resonance frequency due to surface waviness of BNNT as compared to straight BNNT. The future perspective of this study is to investigate methods to optimize the wavy structure of BNNTs for improved biomolecule detection. This could involve studying the effect of different wave patterns, sizes, and amplitudes on the sensor's sensitivity and selectivity.

Lyotropic Boron Nitride Nanotube Liquid Crystals: Preparation, Characterization, and Wet-Spinning for Fabrication of Composite Fiber

Microfiber fabrication via wet-spinning of lyotropic liquid crystals (LCs) with anisotropic nanomaterials has gained increased attention due to the microfibers' excellent physical/chemical properties originating from the unidirectional alignment of anisotropic nanomaterials along the fiber axis with high packing density. For wet-spinning of the microfibers, however, preparing lyotropic LCs by achieving high colloidal stability of anisotropic nanomaterials, even at high concentrations, has been a critically unmet prerequisite, especially for recently emerging nanomaterials. Here, we propose a cationically charged polymeric stabilizer that can efficiently be adsorbed on the surface of boron nitride nanotubes (BNNTs), which provide steric hindrance in combination with Coulombic repulsion leading to high colloidal stability of BNNTs up to 22 wt %. The BNNT LCs prepared from the dispersions with various stabilizers were systematically compared using optical and rheological analysis to optimize the phase behavior and rheological properties for wet-spinning of the BNNT LCs. Systematic optical and mechanical characterizations of the BNNT microfibers with aligned BNNTs along the fiber axis revealed that properties of the microfibers, such as their tensile strength, packing density, and degree of BNNT alignment, were highly dependent on the quality of BNNT LCs directly related to the types of stabilizers.

Coaxial heterostructure formation of highly crystalline graphene flakes on boron nitride nanotubes by high-temperature chemical vapor deposition

We develop a high-temperature chemical vapor deposition of highly crystalline graphene on the surface of boron nitride nanotubes (BNNTs). The growth of few-layer graphene flakes on BNNT templates was confirmed by scanning transmission electron microscopy. Based on an investigation of the effect of growth temperature and growth time on defect density, graphene with relatively high crystallinity was obtained at 1350 °C. The absence of undesirable alterations in the BNNT lattice during graphene growth was verified by multiple analyses. The high-temperature growth of heterolayers would assist in the advancement of nanodevices that coaxially combine graphene and boron nitride.

Boron Nitride Nanotubes: Force Field Parameterization, Epoxy Interactions, and Comparison with Carbon Nanotubes for High-Performance Composite Materials

Boron nitride nanotubes (BNNTs) are a very promising reinforcement for future high-performance composites because of their excellent thermo-mechanical properties. To take full advantage of BNNTs in composite materials, it is necessary to have a comprehensive understanding of the wetting characteristics of various high-performance resins. Molecular dynamics (MD) simulations provide an accurate and efficient approach to establish the contact angle values of engineering polymers on reinforcement surfaces, which offers a measure for the interaction between the polymer and reinforcement. In this research, MD simulations and experiments are used to determine the wettability of various epoxy systems on BNNT surfaces. The reactive interface force field (IFF-R) is parameterized and utilized in the simulations to accurately describe the interaction of the epoxy monomers with the BNNT surface. The effect of the epoxy monomer type, hardener type, local atomic charges, and temperature on the contact angle is established. The results show that contact angles decrease with increases in temperature for all the epoxy/hardener systems. The bisphenol-A-based epoxy system demonstrates better wettability with the BNNT surface than the bisphenol-F based epoxy system. Furthermore, the MD predictions demonstrate that these observations are validated with experimental results, wherein the same contact angle trends are observed for macroscopic epoxy drops on nonwoven nanotube papers. As wetting properties drive the resin infusion in the reinforcement materials, these results are important for the future manufacturing of high-quality BNNT/epoxy nanocomposites for high-performance applications such as aerospace and aeronautical vehicles.

Dispersion Enhancement of Boron Nitride Nanotubes in a Wide Range of Solvents Using Plant Polyphenol-Based Surface Modification

Boron nitride nanotubes (BNNTs) have gained significant attention as a nanofiller additive to enhance the mechanical and thermal properties of polymer composites. However, despite the advancements in BNNT large-scale synthesis methods, the inherent hydrophobicity and the presence of van der Waals attraction hinder their potential application due to poor dispersion in polar and/or nonpolar solvents. In this communication, a facile deposition approach of plant-based polyphenols intercalated with an amine source was postulated. Given the economic advantage and ease of deposition, tannic acid (TA) was directly deposited onto the BNNT surface to enunciate hydrophilic attributes. Afterward, decylamine (DA) was introduced into the BNNT-TA (BNNT-TA–DA) to heighten the BNNT interaction with the polymeric system. The dried BNNT-TA and BNNT-TA–DA powders can be readily redispersed at various concentrations in polar and nonpolar solvents, enhancing the BNNT dispersion and interaction with the polymeric matrix to improve the composite performance. Moreover, to demonstrate the interfacial modification viability, BNNT-TA–DA was used as a filler in epoxy resin to form polymer composites. The fabricated composites displayed 26.8% tensile stress and 52.2% breakpoint of strain increases compared to those of the neat polymer at 1 wt % loading.

Research on the surface structure engineering of boron nitride nanotubes and mechanism of their regulation on the properties of epoxy composite dielectric

Adding nanofillers to epoxy resin matrices is a common approach to achieve their multi-function, among which boron nitride nanotubes (BNNTs) with one-dimensional nanostructures have attracted much attention because of their ultra-high thermal conductivity, wide energy level band gap, high aspect ratio and mechanical strength. Yet, the strong π-π non-covalent bonding and lip-lip interactions make BNNTs prone to agglomeration in the epoxy resin matrix. Moreover, the different physicochemical properties of BNNTs and epoxy resins as well as the chemical inertness of BNNTs surface lead to the lack of effective interfacial interaction between BNNTs and epoxy resin matrix. Therefore, the performance of the epoxy composite dielectric is not enhanced by simple blending solely, but will even have the opposite effect. To address the problems of BNNTs, in this article, the surface structure of BNNTs was constructed from the perspective of interface modulation by using sol-gel method to coat mesoporous silica (mSiO<sub>2</sub>) on BNNTs surface and further introducing silane coupling agent (KH560). The results indicate that constructing the surface structure of BNNTs can optimize the level of interfacial interaction between BNNTs and epoxy resin matrix, which results in stronger interfacial connection and elimination of internal pore phenomenon. The dielectric constant and loss of the composite dielectric prepared in this way were further reduced, reaching 4.1 and 0.005 respectively at power frequency, which was significantly lower than that of pure epoxy resin. At the same time, the mechanical toughness (3.01 MJ/m<sup>3</sup>) and thermal conductivity (0.34 W/(m·K)) were greatly improved compared with pure epoxy resin. In addition, the unique nano-mesoporous structure of mSiO<sub>2</sub> endowed the composite dielectric with a large number of deep traps, which effectively hinders the migration of electrons, thereby improving the electrical strength of the composite dielectric, and the breakdown field strength reached 95.42 kV/mm. Further, Tanaka multinuclear model was used to systematically investigate the interfacial mechanism of BNNTs surface structure construct on dielectric relaxation and trap distribution of composite dielectrics. The above results indicated that the good interfacial interaction between BNNTs and epoxy resin matrix was crucial for the establishment of the micro-interface structure and the improvement of macroscopic properties of composite dielectrics. This paper offered a novel idea for the multifunctionalities of epoxy resin, and also provided some experimental data support for revealing the correlation between surface properties of nano-fillers, microstructure of composite dielectric and macroscopic properties.

Quantum DFT methods to explore the interaction of 1-Adamantylamine with pristine, and P, As, Al, and Ga doped BN nanotubes

Nanostructures, nowadays, found growing applications in different scientific and industrial areas. Nano-coins, nanosheets, and nanotubes are used in medical applications as sensors or drug delivery substances. The aim of this study is to explore the adsorption of 1-Adamantylamine drug on the pristine armchair boron nitride nanotubes (BNNTs) with BNNT(5,5), BNNT(6,6), and BNNT(7,7) chirality along with the P, As, Al and Ga-doped BNNTs, using the quantum mechanical density functional methods. Considering the fact that dispersion effects are important in the case of weak Van der Waals interactions, computations have been done using B3LYP hybrid functional with the implementation of the D3(BJ) empirical dispersion correction methods. Quantum theory of atoms in molecules, natural bonding orbitals, and Kohn–Sham orbitals were used to investigate the nature and type of the adsorption process. The results showed that, while the adsorption of 1-Adamantylamine on the outer surface of pristine BNNT is physical in nature, doping can improve the ability of detracted BN to adsorb the drug through chemical bonds. Also, it was found that, by increasing the radius of the BNNT the adsorption energy was decreased. In conclusion, results of the present work suggest that, Ga doped nanotube, due the chemisorption, is not an ideal nanotube in drug delivery of 1-Adamantylamine drug, whereas, the other studied cases physiosorbed the drug, and may not have serious problem in release of the 1-Adamantylamine drug.

PRISTINE AND GROUP IV DOPED BORON NITRIDE SINGLE-WALL NANOTUBES FOR HYDROGEN STORAGE: A DENSITY FUNCTIONAL THEORY COMPUTATIONAL INVESTIGATION

In this report, a density functional theory (DFT) computational approach was used to investigate the structural and electronic properties of molecular hydrogens adsorbed on single-walled boron nitride nanotubes (BNNTs) with/without doped by group IV elements, such as carbon (C), silicon (Si), and germanium (Ge) atom. The twelve hydrogen molecules (H2) were added to the outer surfaces of BNNT frameworks. Geometry optimization calculations were performed to find the local energy minima of the BNNTs nanostructures with the molecular hydrogens at the DFT/B3LYP/6-31G level of theory. By employing single-point calculations at the B3LYP/6-31G* level of theory, the equilibrium geometric structures were then utilized to find the electronic structures of hydrogen molecules adsorbed on the surfaces of BNNT frameworks. The results showed that the bond lengths of B-N are in the range of1.44 Å – 1.48 Å. The optimized distances of hydrogen molecules from the surfaces of BNNTs were predicted to be 3.1 Å – 3.2 Å. Moreover, the computed HOMO-LUMO energies of molecular hydrogens adsorbed on the surface of BNNTs are about 2.2 eV – 4.3 eV. For the surface map of HOMO, the electron density distribution of hydrogen molecules adsorbed on the surface of pristine BNNT was localized in the N-tip. While in the case of doped BNNTs, the electron densities of HOMOs were focused on the group IV elements. The B-tips on the pristine and doped BNNTs possess the major contribution to the LUMO.

Al- and Ga-embedded boron nitride nanotubes as effective nanocarriers for delivery of rizatriptan

Motivated by earlier experimental and theoretical studies on the potential of different nanostructures for drug delivery, the adsorption and electrical sensitivity of pristine, Al- and Ga-embedded (8,0) boron nitride nanotubes (BNNTs) to a rizatriptan (RZ) molecule are explored using dispersion-corrected density functional density calculations. The RZ molecule is shown to be weakly adsorbed on pristine BNNT, with a modest adsorption energy of −0.46 eV and only a minor impact on its electronic properties. The replacement of a B atom with an Al or Ga promotes the reactivity of the BNNT toward the RZ molecule, as evidenced by calculated adsorption energies and charge-transfer values. Once the RZ molecule is introduced onto the BNNTs, the band gap of the tubes narrows. However, the amount of reduction in band gap values of Al- or Ga- embedded BNNT is more pronounced than that of pristine tube. As solvent effects are included, the desorption times of RZ from the surface of BNNTs are expected to be shortened. The influence of surface charge on the adsorption process of RZ molecules, as well as curvature effects, is thoroughly investigated. Overall, the high sensitivity, reasonable adsorption energies, and fast desorption suggest that Al- and Ga-embedded BNNTs might be served as effective drug delivery systems for RZ.

High-Throughput computational screening of Single-atom embedded in defective BN nanotube for electrocatalytic nitrogen fixation

The boron nitride nanotubes (BNNTs) have been widely used in various energy applications such as hydrogen storage, gas sensor, carbon dioxide reduction reaction, and so on. Herein, the potential application of BNNT-based catalysts was explored in electrocatalytic nitrogen reduction reaction (eNRR) by density functional theory (DFT) computations. A series of single metal/non-metal atoms (18 transition metals (3d ∼ 5d) and 6 non-metals (B, C, N, Si, P, and As)) supported on the defective BNNT were investigated. Among them, Os-doped (Os@BNNT) single-atom catalyst (SAC) can significantly promote the NRR process, and possess a rather low overpotential (0.31 V), as well as high selectivity over HER competition. The confined Os atom not only serves as an electron donor to supply electrons for NRR, but also acts as a channel for interfacial charge transfer between substrate and NRR intermediates. Moreover, the curved surface of BNNT can decrease the barrier for protonating *NH2 to·NH3. The synergistic collaboration of single-atom Os catalyst and curved surface of BNNT facilitates the NRR process. Our findings open up a new avenue for designing novel nanotube-based materials as eNRR electrocatalysts.

Molecular engineering of the surface of boron nitride nanotubes for manufacture of thermally conductive dielectric polymer composites

Recent developments in microelectronic devices have led to rising demand for polymeric nanocomposites that can simultaneously deliver enhanced thermal conduction and electrical insulation. Boron nitride nanotube (BNNT) is one of the most promising fillers for the fabrication of such composites. While being electrically insulating, effective crystal lattice vibrations allow BNNTs to achieve thermal conductivity values that can even surpass that of diamond. However, when BNNTs are surface functionalized and incorporated within polymers, their lattice vibrations are significantly suppressed, resulting in polymeric nanocomposites with thermal conductivity values only a fraction of what BNNTs can achieve in air. The aim of this study is to shed light on the underlying cause of this challenge for thermally conductive, dielectric polycarbonate (PC)/BNNT nanocomposites that were produced using two distinct surface functionalization approaches. By incorporation of BNNTs in PC, the thermal conductivity values were significantly increased. However, depending on nanotubes’ concentration, the thermal conductivity of pristine BNNTs in PC were comparable or superior to those of the functionalized nanotubes. Theoretical analysis and experimental characterization have been conducted to elucidate the fundamental impacts of surface functionalization on the lattice vibrations of BNNTs and their subsequent effects on the thermal properties of dielectric BNNT composites.