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Highlights Developed more efficient boron activation strategies, while establishing various low-melting growth systems. The preparation temperature of boron nitride nanotubes has been reduced to 850 °C.

A novel binary transition metal oxide (NiFe2O4) nanosphere catalyst with a diameter of 500 nm has been synthesized by the hydrothermal reaction, which can efficiently catalyze the formation of hexagonal boron nitride nanotubes (BNNTs) with high‐yield and large aspect ratio. Based on the temperature dependence of the product phase composition and microstructure, combined with results generated using single‐component catalysts, the BNNTs formation process can be summarized as follows: NiFe2O4 reacts with NH3 to generate Fe0.64Ni0.36, which dissolves to form a liquid‐phase Ni‐Fe alloy at high temperatures, where the B component in the precursor and the N atom formed by the decomposition of NH3 diffuse on the surface of the Ni‐Fe alloy; when the concentration of B and N exceed the saturation threshold, hollow BNNTs containing catalyst at the tips are precipitated. The formation process is dominated by a vapor‐liquid‐solid mechanism with tip‐growth mode, where the synergistic catalytic effect of the Ni‐Fe binary system promotes a high yield of large aspect ratio BNNTs. [ABSTRACT FROM AUTHOR]

In this research, piezoelectric and heat-dissipating boron nitride nanotube (BNNT)/polyvinylidene fluoride (PVDF) nanocomposite thin films having superior properties for wearable sensing applications are introduced. Neat and 2.5 wt % (BNNT2.5)- and 5.0 wt % BNNT (BNNT5.0)-embedded PVDF thin films were prepared by first producing gel-like electrospun nanofibers followed by hot-rolling, respectively. The piezoelectric performance of BNNT5.0 was as high as 128.0 ± 5.4 mV under 300 kPa, while Neat and BNNT2.5 showed 9.9 ± 0.1 and 22.7 ± 8.8 mV, respectively. Furthermore, BNNT2.5 also presents almost 9 times and BNNT5.0 presents more than 3 times higher thermal conductivities of 0.89 ± 0.40 and 0.32 ± 0.10 W/mK, respectively, compared to Neat (0.10 ± 0.01 W/mK) and both present very high thermal resistance with no phase change up to 180 °C and less than 4% shrinkage even at 200 °C, while Neat begins melting at 120 °C. BNNT2.5 and BNNT5 showed a high water-repelling property and mechanical strength as well. Tensile strengths and elongation for BNNT2.5 and BNNT5.0 were 18.1 MPa with 52.1% and 21.2 MPa and 34.0%, respectively. They both showed a low moisture absorption property with high water repellence with stable and hydrophobic water contact angles (92.2° with only 0.4° change for BNNT2.5 and 103.6° with 2.4° change for BNNT5.0 in 30 s), while Neat was in the hydrophilic region. Consequently, BNNT/PVDF films with highly enhanced piezoelectric-sensing and heat-dissipating properties and mechanical, thermal, and moisture resistance can be applicable for various wearable sensing environments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The boron nitrides as excellent sensors are adopted to detect some harmful gases. The adsorption sites and lengths of the boron nitrides are very important to improve the adsorption capacity. The structures, stabilities and electronic properties of the COBmNm and CO@BmNm (m=48, 96 and 144) nanotubes with different lengths have been investigated by using density functional theory. The longer BmNm, COBmNm and CO@BmNm clusters are more stable. The adsorption of the CO molecules at the ends of BmNm nanotubes competes with the insertion of the CO molecules in the BmNm nanotubes. The COBmNm clusters exhibit higher chemical reactivity than the CO@BmNm clusters. The lengths of the BmNm nanotubes have little effect on the chemical reactivity of the nanotubes. The charge transfer amounts of the O atoms increase while those of the C atoms of the COBmNm and CO@BmNm clusters are almost the same with the increase of cluster lengths. The CO molecules lose fewer electrons (0.174|e|, 0.164|e|, 0.158|e|) to the BmNm nanotubes of the COBmNm clusters while the CO molecules obtain fewer electrons (−0.028|e|, −0.045|e|, −0.045|e|) from the BmNm nanotubes of the CO@BmNm clusters. [ABSTRACT FROM AUTHOR]

In this study, boron nitride nanotubes (BNNTs) were utilized as covering and reinforcing materials owing to their extraordinary insulation and extremely high hydrophobicity. The gas–liquid–solid annealing process was used to manufacture the BNNT stainless-steel filter, with a 120 mesh stainless steel filter serving as the substrate and B2O3 as the raw material. Scanning electron microscopy showed that the average diameter of the nanotubes was 0.40 μm. The BNNTs were bamboo shaped, and the BNNT stainless-steel filter was superhydrophobic, with a water contact angle was 150.49°. The materials demonstrated good separation performance, as indicated by the separation results obtained under four different test conditions (0 and 0.3 MPa, 3 and 10 mL/min). The solid–liquid separation effect of the BNNT stainless-steel filter was better than that of the Teflon filter. In oil–water separation experiments with varying water contents (1.2 and 5.8 wt%), the BNNT stainless-steel filter was more hydrophobic. Based on the results, the role of the hydrodynamic method in the separation of two superhydrophobic materials is discussed. The method introduced in this study can serve as a reference for the application of other filtration separation technologies. Furthermore, the superior separation performance of the superhydrophobic BNNT stainless-steel filter may enable the quick, effective, and continuous collection of water contaminated with oil, giving it a wide range of potential applications.

For the dispersion of boron nitride nanotubes (BNNTs), noncovalent or covalent functionalization methods in a solvent with complex procedures, including acidic treatments, are widely used. Herein, we propose a solvent-free functionalization of BNNTs using a facile atmospheric-pressure cold-plasma treatment method. The plasma-treated BNNTs exhibited nearly threefold enhanced dispersibility and fourfold improved long-term dispersion stability compared with pristine BNNTs. These remarkable enhancements were attributed to the presence of the O atoms and OH molecules generated in the plasma, which reacted with the BNNT surface to form B–N–O and OH bonds. Consequently, the wettability of the plasma-treated BNNTs was transformed to superhydrophilicity, resulting in the exfoliation of the BNNT bundles in water. Small-angle X-ray scattering measurements confirmed the successful exfoliation of plasma-treated BNNTs from bundled structures in water. From an application perspective, the atmospheric-pressure cold plasma method offers a solvent-free, straightforward, and robust approach for BNNT functionalization, eliminating the need for additional post-procedures to remove residual surfactants from BNNTs. [ABSTRACT FROM AUTHOR]

We have investigated the hydrogen energy storage potentials of (8, 8) single-walled carbon nanotubes (SWCNTs) and (8, 8) single-walled boron nitride nanotubes (SWBNNTs) using density functional theory. Calculations of the electronic properties of the studied systems were performed using the Perdew, Burke and Ernzerhof (PBE) exchange correlation function of the generalized gradient approximation. The optical adsorption response of the pure and hydrogen-adsorbed systems was determined within G0W0 approximations with both RPA and BSE. From the obtained results, it was found that both (8, 8) SWBNNT and SWCNT were stable when the hydrogen molecule was 8.72 m away from the adsorption surface. SWBNNT was found to show stronger adsorption from 5 to 15 eV, which is in the UV range. On the other hand, SWCNT adsorbs hydrogen in the 0–5 eV which falls in the UV–Vis range, with higher adsorption recorded from 0 to 2.4 eV, which corresponds to the visible range. Although both systems adsorb hydrogen, (8, 8) SWCNT is reported to be better than (8, 8) SWBNNT due to its ability to adsorb in the visible region of the electromagnetic spectrum. Therefore, SWCNT is regarded as a better candidate for hydrogen energy storage under ambient conditions. [ABSTRACT FROM AUTHOR]

Boron nitride nanotubes (BNNTs) are promising materials due to their unique physical and chemical properties. Fabrication technologies based on gas-phase reactions reduce the control and collection efficiency of BNNTs due to reactant and product dispersion within the reaction vessel. A surface growth method that allows for controllable growth of BNNTs in certain regions using a preburied boron source is introduced. This work leverages the high solubility of boron in metals to create a boronized layer on the surface which serves as the boron source to confine the growth of BNNTs. Dense and uniform BNNTs are obtained after loading catalysts onto the boronized substrate and annealing under ammonia. Confirmatory experiments demonstrate that the boride layer provides boron for BNNTs growth. Furthermore, the patterned growth of BNNTs is realized by patterning the boronizing region, demonstrating the controllability of this method. In addition, the Ni substrate with BNNTs growth exhibits better performance in corrosion resistance and thermal conductivity than pure Ni. This study introduces an alternative strategy for the surface growth of BNNTs based on boron source design, which offers new possibilities for the controllable preparation of BNNTs for various applications. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this research is to extract the natural frequencies of a circular plate containing a central hole reinforced with boron nitride nanotubes (BNNTs) and containing piezoelectric layers. Design/methodology/approach: A unit cell shall be taken into account for the simulation of BNNT's volume fraction. A rectangular micromechanical model is used to obtain the mechanical properties of unit cell of piezoelectric fiber-reinforced composite (PFRC). The three-dimensional (3D) elasticity method is presented to provide the relationship between displacements and stresses. The one-dimensional differential quadrature method (1D-DQM) and the state-space methodology are combined to create the semi-analytical technique. The state-space approach is utilized to implement an analytical resolution in the thickness direction, and 1D-DQM is used to implement an approximation solution in the radial direction. The composite consists of a polyvinylidene fluoride (PVDF) matrix and BNNTs as reinforcement. Findings: A study on the PFRC is carried, likewise, the coefficients of its properties are obtained using a micro-electromechanical model known as the rectangular model. To implement the DQM, the plate was radially divided into sample points, each with eight state variables. The boundary situation and DQM are used to discretize the state-space equations, and the top and bottom application surface conditions are used to determine the natural frequencies of the plate. The model's convergence is assessed. Additionally, the dimensionless frequency is compared to earlier works and ABAQUS simulation in order to validate the model. Finally, the effects of the thickness, lateral wavenumber, boundary conditions and BNNT volume fraction on the annular plate's free vibration are investigated. The important achievements are that increasing the volume fraction of BNNTs increases the natural frequency. Originality/value: The micromechanical "XY rectangle" model in PFRC along with the three-dimensional elasticity model is used in this literature to assess how the piezoelectric capabilities of BNNTs affect the free vibration of polymer-based composite annular plates under various boundary conditions. [ABSTRACT FROM AUTHOR]

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.

Recent advancements have shown great promise in utilizing wire‐fed direct energy deposition (DED) for building aluminum alloy structures. However, utilizing the wire‐fed DED approach for fabricating metal matrix composite structures remains a significant challenge. Herein, a wire‐based additive manufacturing process is used to successfully produce a 1D boron nitride nanotube (BNNT)‐reinforced aluminum composite with high strength. Al‐BNNT electrode is developed in house. The microstructural changes that occur during layer‐by‐layer deposition are investigated. The grain morphology changes from equiaxed grains in the bottom layer to columnar grains in the top layer. BNNTs act as nuclei to promote the formation of equiaxed grains and interfacial compounds (AlN and AlB2) during solidification. This results in improved strength, with Al‐BNNT composite exhibiting a tensile strength of 47 MPa, 2.3 times higher than its pure Al. Higher strength is attributed to the retention and uniform distribution of BNNT reinforcement in the melt pool, leading to effective load transfer. This study demonstrates the potential of additive manufacturing for producing high‐performance metal matrix composites with novel 1D reinforcements and improved multifunctional properties. [ABSTRACT FROM AUTHOR]

To date, there has been limited reporting on the fabrication and properties of macroscopic sheet assemblies (specifically buckypapers) composed of carbon/boron nitride core–shell heteronanotubes (MWCNT@BNNT) or boron nitride nanotubes (BNNTs). Herein we report the synthesis of MWCNT@BNNTs via a facile method involving Atmospheric Pressure Chemical Vapor Deposition (APCVD) and the safe h-BN precursor ammonia borane. These MWCNT@BNNTs were used as sacrificial templates for BNNT synthesis by thermal oxidation of the core carbon. Buckypaper fabrication was facilitated by facile sonication and filtration steps. To test the thermal conductivity properties of these new buckypapers, in the interest of thermal management applications, we have developed a novel technique of advanced scanning thermal microscopy (SThM) that we call piercing SThM (pSThM). Our measurements show a 14% increase in thermal conductivity of the MWCNT@BNNT buckypaper relative to a control multiwalled carbon nanotube (MWCNT) buckypaper. Meanwhile, our BNNT buckypaper exhibited approximately half the thermal conductivity of the MWCNT control, which we attribute to the turbostratic quality of our BNNTs. To the best of our knowledge, this work achieves the first thermal conductivity measurement of a MWCNT@BNNT buckypaper and of a BNNT buckypaper composed of BNNTs not synthesized by high energy techniques. [ABSTRACT FROM AUTHOR]

Nanotubes, such as boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs), exhibit excellent mechanical properties. In this work, high-quality BNNTs were synthesized by ball milling and annealing. Subsequently, well-dispersed 3vol% BNNTs/Cu and 3vol% CNTs/Cu composites were successfully prepared using ball milling, spark plasma sintering, and followed by hot-rolling. Moreover, the mechanical properties and strengthening mechanisms of BNNTs/Cu and CNTs/Cu composites were compared and discussed in details. At 293 K, both BNNTs/Cu and CNTs/Cu composites exhibited similar ultimate tensile strength (UTS) of ∼404 MPa, which is approximately 170% higher than pure Cu. However, at 873 K, the UTS and yield strength of BNNTs/Cu are 27% and 29% higher than those of CNTs/Cu, respectively. This difference can be attributed to the stronger inter-walls shear resistance, higher thermomechanical stability of BNNTs, and stronger bonding at the BNNTs/Cu interface as compared to the CNTs/Cu interface. These findings provide valuable insights into the potential of BNNTs as an excellent reinforcement for metal matrix composites, particularly at high temperature. [ABSTRACT FROM AUTHOR]

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.

The adsorption behavior of the anti-neurodegenerative drug Levodopa (LD) on pristine and aluminum-doped (Al-doped) boron nitride nanotubes (BNNTs) has been investigated in the current study using the density functional theory (DFT) approach at the B3LYP/6-31G** level of theory. The aim was to improve and expand boron nitride nanotubes drug carriers used in biomedical systems, i.e., drug delivery systems. The binding qualities of pure and doped BNNT complexes as adsorbents with LD were explored using the natural bond orbitals (NBO) analysis, density of state (DOS), electrical and structural characteristics, and atoms in molecules (AIM) properties. Due to doping heteroatoms in the adsorbent's molecular structure, the obtained data reveal a gradual shift in LD adsorption, with a significant rise in negative adsorption energy values. The electronic perturbation caused by doped atoms, particularly Al, improves boron nitride nanotube sensitivity to adsorbed Levodopa, and the electronic properties of the nanotubes are altered following Levodopa adsorption in the complex. As the frontier molecular orbital distributions were transferred from LD to BNNTs in the complex of BNNT–LD, it was also shown that LD drugs could be loaded on pristine and Al-doped BNNTs while remaining safe from interactions with other substances. Furthermore, AIM analysis based investigations revealed that O–Al interaction in LD adsorbed on Al-doped boron nitride nanotube and O–N interaction in the BNNT–LD complex are partially covalent. Finally, the findings showed that pristine and Al-doped BNNT could be used in drug delivery processes by controlling the loaded LD contribution to future interactions. [ABSTRACT FROM AUTHOR]

A multi-scale higher-order continuum model is developed for the investigation of the mechanical properties and buckling behaviors of boron nitride nanotubes (BNNTs) at finite temperature. A meshless local Petrov–Galerkin (MLPG) computational scheme is constructed based on the proposed hyper-elastic constitutive model to simulate the deformations of BNNTs. The Young's modulus, shear modulus and Poisson's ratio of BNNTs are studied. The buckling patterns of BNNTs subjected to compression, bending and twisting at finite temperature are simulated, respectively. The results are in good agreement with those obtained by other methods. [ABSTRACT FROM AUTHOR]

Context: In this study, the electronic transport of (6, 3) two side-closed single-walled boron nitride nanotubes ((6, 3) TSC-SWBNNTs) located between two electrodes of (5, 5) conductive carbon nanotubes is investigated. Introducing carbon impurities instead of nitrogen and boron atoms in different locations of two side-closed (6, 3) SWBNNTs would change the transmission spectrum and reduce the gap. As the bias voltage increases, the peaks of the transmission spectrum become sharper and narrower. Substituting carbon impurities instead of nitrogen atoms leads to larger currents than substituting carbon impurities instead of boron. For the carbon impurity instead of N atoms, the current in the center is observed to be larger than currents on the left and right sides. In addition, negative resistance can be seen in current–voltage diagrams, which are used in the construction of high-speed electronic switches in electrical circuits. Method : Due to the larger number of atoms, the study of structures by the common approach is time-consuming and some times impossible. Hence, in this research, the Quantum ATK simulation software is used to investigate the characteristics of electronic transport. For this purpose, the Slater-Koster method and the tight-closure approximation are used. In this method, the non-equilibrium Green function (NEGF) approach is employed. [ABSTRACT FROM AUTHOR]

High-purity and high-yield boron nitride nanotubes with large aspect ratio were prepared by a facile two-step process, including the synthesis of boron/nickel containing precursors by precipitation reactions and subsequent thermally catalytic chemical vapor deposition reactions. The influence of catalyst content and annealing temperature on the phase composition and microstructure of the products were investigated. The results show that it is difficult to exert the catalytic effect of nickel-based catalyst at low temperatures (

While numerical modelling of different types of nanofluids in various microchannel heat sink geometry under different flow conditions are many, few involved utilizations of experimental data. Reports so far have indicated the potential cooling capability of nanofluids in general, yet none have investigated the effects of the surfactant alone on the fluid flow, in particular the thermofluid flow pattern. This paper reports the results of a numerical simulation with CFD on the fluid flow of Triton TX-100 surfactant with boron nitride nanotubes (BNN) in distilled water (base fluid) at 30 and 50 °C. The nanofluid (BNNT) operated at high temperature provided a lower thermal resistance. A higher pumping power was found for BNNTs and TX-100 at 30 ℃ compared to distilled water at both temperatures. The outcomes of the present study provide a better understanding of flow characteristic and flow visualization along a microchannel heat sink so that better design decision can be made for improvement of this application for different needs. [ABSTRACT FROM AUTHOR]

Boron nitride nanotube (BNNT) has attracted recent attention owing to its exceptional material properties; yet, practical implementation in real‐life applications has been elusive, mainly due to the purity issues associated with its large‐scale synthesis. Although different purification methods have been discussed so far, there lacks a scalable solution method in the community. In this work, a simple, high‐throughput, and scalable purification of BNNT is reported via modification of an established sorting technique, aqueous polymer two‐phase extraction. A complete partition mapping of the boron nitride species is established, which enables the segregation of the highly pure BNNT with a major impurity removal efficiency of > 98%. A successful scaling up of the process is illustrated and provides solid evidence of its diameter sorting behavior. Last, towards its macroscopic assemblies, a liquid crystal of the purified BNNT is demonstrated. The effort toward large‐scale solution purification of BNNT is believed to contribute significantly to the macroscopic realization of its exceptional properties in the near future. [ABSTRACT FROM AUTHOR]

Boron nitride nanotubes (BNNTs) are analogous nanostructures to carbon nanotubes (CNTs), possessing similar properties such as Young's modulus and thermal conductivity, but superior resistance to oxidation and thermal stability. In addition, BNNTs are insulating materials, whereas CNTs are electrically conductive. They could be used as reinforcements in polymeric matrices as heat dissipators or as protective coatings in harsh environments. However, when incorporating them into polymers, one main drawback is their tendency to agglomerate. To improve their dispersion, covalent surface modification can be applied, with solvent‐free approaches being preferred. Herein, we used syngas photo‐initiated chemical vapour deposition (PICVD) to incorporate oxygen functionalities on the surface of BNNT. X‐ray photoelectron spectroscopy analysis showed a highly oxidized BNNT surface after treatment. In addition, a decrease in water contact angle and an increase in surface energy were observed for the treated material. These results open new possibilities to incorporate hydrophilic BNNTs surfaces into polar polymers or other matrices of interest. [ABSTRACT FROM AUTHOR]

Abstract Highly crystalline and few-walled boron nitride nanotubes (BNNTs) had been synthesized by laser ablation using only ammonia borane as a precursor. As a molecular precursor, ammonia borane supplied both B and N atoms with a ratio of 1:1, and BNNTs were formed via the homogeneous nucleation of BN radicals, not the growth from boron nano-droplets, which is a generally accepted growth mechanism of the laser-grown BNNTs. Owing to the absence of amorphous boron impurities, the van der Waals interaction among BNNTs became effective and thus a BNNT fibers was formed spontaneously during the BNNT synthesis. The BNNT growth and the subsequent fiber formation are found to occur only at high pressures of a surrounding gas. The mechanism behind the critical role of pressure was elucidated from the perspective of reaction kinetics and thermal fluid behaviors. A polarized Raman study confirmed that the BNNT fiber formed exhibits a good alignment of BNNTs, which implies great potential for continuous production of high-quality BNNT fibers for various applications.

The effective identification of the active catalytic phase is essential to elucidate the growth mechanism of boron nitride nanotubes (BNNTs) and realize their controllable and scalable synthesis. However, owing to the complexity of chemical reactions during BNNT growth via chemical vapor deposition (CVD) and the lack of techniques for in situ characterization at high temperatures (1100–1300 °C), identifying the true catalyst during BNNT growth is challenging. Herein, an aluminum (Al)‐based active catalyst for BNNT growth via CVD is investigated. The initial Al2O3 nanoparticle catalyst precursor is transformed into an Al‐B phase prior to BNNT growth. Based on our density functional theory‐based molecular dynamic simulations of BNNT nucleation, AlB x (x = 1.5 to 2) shows catalytic activity for the formation of BN chains and BN six‐membered rings. Confirmatory experiments demonstrate that AlB2 is the active Al‐based catalyst during BNNT growth. A nanocomposite is prepared from cellulose nanocrystal, and purified BNNTs exhibited a high in‐plane thermal conductivity of 13.33 W m−1 K−1 at 20 wt% BNNTs. A further application for light‐emitting diode chip cooling demonstrates excellent heat‐dissipation performance of the nanocomposite film. Thus, this study can guide the controllable synthesis of high‐quality BNNTs and facilitate their use in thermal interface materials.

Biohybrid robots, or bio‐bots, integrate living and synthetic materials following a synergistic strategy to acquire some of the unique properties of biological organisms, like adaptability or bio‐sensing, which are difficult to obtain exclusively using artificial materials. Skeletal muscle is one of the preferred candidates to power bio‐bots, enabling a wide variety of movements from walking to swimming. Conductive nanocomposites, like gold nanoparticles or graphene, can provide benefits to muscle cells by improving the scaffolds' mechanical and conductive properties. Here, boron nitride nanotubes (BNNTs), with piezoelectric properties, are integrated in muscle‐based bio‐bots and an improvement in their force output and motion speed is demonstrated. A full characterization of the BNNTs is provided, and their piezoelectric behavior with piezometer and dynamometer measurements is confirmed. It is hypothesized that the improved performance is a result of an electric field generated by the nanocomposites due to stresses produced by the cells during differentiation. This hypothesis is backed with finite element simulations supporting that this stress can generate a non‐zero electric field within the matrix. With this work, it is shown that the integration of nanocomposite into muscle‐based bio‐bots can improve their performance, paving the way toward stronger and faster bio‐hybrid robots. [ABSTRACT FROM AUTHOR]

Graphene nanoribbons are prepared inside boron nitride nanotubes by liquid phase encapsulation and subsequent annealing of 1,2,4‐trichlorobenzene. The product is imaged with high‐resolution transmission electron microscopy, and characterized by optical absorption and Raman spectroscopy. Carbon‐containing material is detected inside the boron nitride nanotubes with energy‐dispersive X‐ray spectroscopy (EDS) and scanning transmission electron microscopy (STEM). The observed structures twist under the electron beam and the characteristic features of nanoribbons appear in the Raman spectra. [ABSTRACT FROM AUTHOR]

There is a need to augment the mechanical strength of titanium alloys to take advantage of their low mass density for structural applications. Herein, the reinforcement potential of boron nitride nanotube (BNNT), a high‐aspect‐ratio nanomaterial with exceptional strength and thermal stability, to engineer nanocomposites based on Ti–6Al–4 V alloy, is interrogated. The stress‐transfer behavior at the matrix/filler interface is programmed by tweaking the extent of chemical reactions during sintering. A twofold improvement in indentation resistance after integrating BNNTs in the alloy due to the crack bridging mechanism is reported. There is a further 50% enhancement in hardness and stiffness as the sintering temperature is raised from 750 to 950 °C. This improvement is attributed to the escalated formation of TiN and TiB phases due to matrix–nanotube interfacial reactions at elevated temperatures. A novel indentation‐based in situ trench testing technique is employed to study the subsurface deformation mechanisms activated in the bulk of the composite specimen. The ceramic interphases promote the indentation resistance by acting as crack deflectors in the microstructure, which promotes the dissipation of mechanical work. These insights can be applied to designing Ti‐BNNT microstructures with desired mechanical properties and deformation characteristics. [ABSTRACT FROM AUTHOR]

This paper introduces contorted hexabenzocoronene (c-HBC) derivatives as a potential universal precursor for use in synthesis of sp2-crystalline carbon materials that have dimensionalities ranging from 1-D to 3-D. Carbon products with different dimensions and high crystallinity were synthesized by controlling the assembly dimensions and intermolecular interactions of c-HBC derivatives, which are largely affected by the edge element and the deposition conditions. Further control of crystallinity was achieved by involving copper vapor; the effect is shown to be limited by the thickness of the assembled c-HBC layer. Study of the carbonization of c-HBC allowed development of an effective strategy to grow graphene-like structure on arbitrary substrates. This ability is expected to be a foundation for designed synthesis of graphitic carbons that have optimum morphology and dimensions for targeted applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Debate regarding the transport mechanisms of water and ions in highly charged one-dimensional (1D) nanochannel continues because of a lack of available experimental data. Here, we present a nanofluidic platform consisting of ≈2.7-nm-diameter boron nitride nanotubes (BNNTs) as a model system, and report the experimental ion transport in these sub-3-nm BNNTs. We elucidate that strong electrostatic interactions between the highly charged tube walls and ions, stemming from the high surface-charge density (378 mC/m2) of BNNTs, play important roles in defining the ion transport mechanism in BNNT pores. Experimental analysis of ion transports supported by numerical the Donnan steric pore model with dielectric exclusion (DSPM-DE) and Derjaguin–Landau–Verwey–Overbeek (DLVO) model elucidate the relationship of the ionic charge density and surface-charge density of the BNNT wall to electrostatic interaction, steric, and dielectric effects. We also demonstrate that BNNTs exhibit higher NaCl separation (≈90%) than commercial reverse-osmosis (≈80%) and nanofiltration (≈60%) membranes under the same experimental conditions, despite having a larger pore size. Our results establish design criteria for developing highly efficient ion-selective membranes for various practical applications. [ABSTRACT FROM AUTHOR]

The trend toward miniaturization, integration and multifunctionality of modern electronics has led to a rapid increase in power density, which makes heat dissipation a critical issue. Despite the great potential of graphite-related nanocomposites in dissipating excess heat to ensure high efficiency and long lifetime of electronic devices, the practical application of these composites is limited by the ultra-low vertical thermal conductivity due to the interfacial thermal resistance between graphite layers. Here, a caterpillar-like hybrid filler was fabricated by the in situ intercalation of boron nitride nanotubes (BNNTs) between expanded graphite (EG) layers based on chemical vapor deposition technology. Owing to the optimized interfacial thermal resistance by forming covalent C-N bonding at the interface of EG and BNNT, the through-plane thermal conductivity of epoxy-based nanocomposites can be up to 5.18 Wm−1 K−1. In addition, the composite possessed electromagnetic interference shielding performance of 33.34 dB while maintaining electrical insulation due to the hierarchical structure. This work provided a new strategy for fabricating polymer-based composites with excellent through-plane thermal conductivity in thermal management applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Electrocatalytic activity of metal doped boron nitride nanotubes for CO 2 reduction has been illustrated. • Rh@BNNT-B vac serves as promising ECO 2 RR catalysts with low limiting potential of −0.06 V for product HCOOH. • This work provides guidance for single-atom engineering on the exploration of the SAC catalysts. Atomically dispersed single metal on defective boron nitride nanotubes (BNNTs) show promising potential for CO 2 electrocatalytic reduction reaction (CO 2 ERR). Using density functional theory calculations, we explore the CO 2 ERR mechanism on single-atom catalysts (SACs) supported on BNNTs as well as assess their electrocatalytic performance of these catalysts. Boron or nitrogen vacancies in BNNTs are doped with palladium, platinum, or rhodium atoms to form three-coordinated metal centers, denoted as M@BNNT-V (M = Pt, Rh, Pd; V = B vacancy or N vacancy). Pt@BNNT with boron vacancies (Pt@BNNT-B vac) demonstrates a tendency to facilitate multi-electron reduction processes leading to the formation of complex molecules such as CH 2 O, CH 3 OH, and CH 4 with a limiting potential (U L) of −0.36 V. Conversely, Rh@BNNT-B vac and Pd@BNWNT-B vac show significantly lower limiting potentials of −0.06 V and −0.12 V, respectively, for the reduction to formic acid (HCOOH), with Rh@BNNT-B vac exhibiting enhanced activity and selectivity. Additionally, the deep reduction to other hydrocarbons or oxygenates, which typically requires potentials of −0.72 V and −0.60 V, appears less likely on both Rh and Pd doped BNNT-B vac , further delineating the nuanced performance differences induced by metal type and coordination environment within the BNNT structure. [ABSTRACT FROM AUTHOR]

AAh boron nitride (BN) crystal, assigned to an orthorhombic space group (No. 31, Pm21), is reported here. This new AAh BN crystal exhibits a `linear' morphology for high-resolution transmission electron microscopy (HRTEM) and a (non-hexagonal) `diagonal' electron-diffraction pattern, which have been experimentally demonstrated in this article. It is also demonstrated that this new crystal is the basic structure of multi-walled BN nanotubes (BNNTs) existing in the form of a helix. The helical AAh BNNTs exist in a metastable phase owing to 〈200〉 texture growth of the orthorhombic crystal, where the energy is ∼15 meV higher than that of stable AB or AA′ BN. It is shown that the typical scanning electron microscope `fluffy cotton-like' morphology of BNNTs is due to secondary growth of diverse BN sheets (including mono-layers) on incoherently scrolled wall strands of BNNTs, providing further evidence for the helical structure with HRTEM evidence for a left-handed helix.

The paper investigates the electronic and thermoelectric transport properties of the molecular bonds of two sided-closed single-walled boron nitride nanotubes (BNNT) (6, 3) with respect to the effect of the contact type. For states with and without inelastic conditions, the conductance spectra as a function of the incident electron energy of two sided-closed single-walled BNNT junctions were investigated in terms of single and six atomic contacts. These spectra are important for studying transport properties through BNNTs. Then, we calculated the currents and energy flux against the bias voltage for BNNTs. The thermopower and electronic thermal conductance were explored against the electron energy for BNNTs. [ABSTRACT FROM AUTHOR]

A fundamental understanding of the thermal behavior of reinforcement materials is crucial to fully exploit their properties in composites. Boron nitride nanotubes (BNNTs), structural analogues to carbon nanotubes, are a strong candidate for nanofillers in high-temperature composites due to their high thermal stability, oxidation resistance, excellent mechanical properties, and high thermal conductivity. In this paper, samples of high-quality, high-purity BNNTs were tested to thermal failure in an inert atmosphere for the first time up to 2500 °C. A significant fraction of the BNNTs survived temperatures as high as 2200°, and the BNNT samples were completely undamaged at temperatures as high as 1800 °C. Boron nitride (BN) nanopowders were tested identically to perform a comparative study, as hexagonal BN is commonly found in purified BNNT samples. Observed color darkening, significant weight loss, an increased boron atomic level, significant weight gain upon oxidation, the presence of boron oxide compounds in an oxidized sample, and the observed boron clusters at the nanoscale indicate dissociation of B-N bonds in the BNNT sample at 2200 °C. The stability of BNNT structures was observed up to 2000 °C, with local/partial wall dissociation or unzipping, and complete survivability of highly crystalline BNNTs is demonstrated up to 1800 °C. This paper presents the first-ever study on extreme temperature thermal stability of purified BNNTs in an inert atmosphere analogous to manufacturing processes for high-temperature nanocomposites. [ABSTRACT FROM AUTHOR]

The reinforcing effect of carbon nanotubes (CNTs) and boron nitride nanotubes (BNNTs) on the interfacial characteristics and tensile behaviors of natural rubber (NR) composites were comparatively investigated using molecular dynamics simulations. A pull‐out simulation was performed to study the interfacial characteristics between CNTs, BNNTs and NR matrices. The results showed that increases of about 56.63% and 90.14% in the interfacial frictional force and interfacial shear strength were obtained for the composites by the incorporation of BNNTs than those by the incorporation of CNTs. A uniaxial tensile process was fulfilled by using the constant true strain rate method to study the mechanical properties of the NR composites reinforced by CNTs and BNNTs. The results indicated that significant increases of 22.34% and 26.59% in the Young's modulus, 4.34% and 19.28% in the yield stress, and 11.07% and 8.01% in the tensile strength were respectively achieved by the incorporation of CNTs and BNNTs as reinforcements. To deeply reveal the deformation mechanisms of the NR composites, the mean square displacement and root‐mean‐square radius of gyration of the NR chains, the fractional free volume in the NR composites, and the interfacial interaction energy were calculated and discussed accordingly. [ABSTRACT FROM AUTHOR]

The use of flexible transparent conductive electrodes (TCEs) as printed heaters offers unique advantages where transparency is a necessary design feature. Many existing TCE materials however suffer from poor flexibility and require complex fabrication processes and thus are not commercially viable for such applications. The design and process optimization of screen‐printable silver metal microgrids over a layer of boron nitride nanotubes (BNNT) to produce highly conductive and mechanically robust transparent heaters with high transparency and low power requirements is reported. Square and hexagonal geometries are investigated alongside varying line width and pitch combinations to produce 16 different grid designs with optical transparency ranging between 65% and 89% and resistance values as low as 2.90 Ω sq−1. The BNNT thin film coating on polyethylene terephthalate substrates provides mechanical stability to the heater architecture by reducing the effects of deformation by up to 400%. The BNNT interlayer also contributes to an increase in thermal performance, achieving temperatures as high as 74.0 °C by initiating electrical sintering of the microgrids during heater operation which increases the Joule heating capacity of the features. Overall, this physical and material optimization provides a low‐cost, printable microgrid architecture for high performing and stable applications as TCE‐based heaters. [ABSTRACT FROM AUTHOR]

The use of boron nitride nanotubes (BNNTs) for fabrication of thermally conductive composites has been explored in the last years. Their elevated thermal conductivity and high mechanical properties make them ideal candidates for reinforcement in polymeric matrices. However, due to their high tendency to agglomerate, a physical or chemical treatment is typically required for their successful incorporation into polymer matrices. Our previous study about the dispersibility of BNNTs allowed determination of good solvents for dispersion. Here, we performed a similar characterization on styrene-butadiene rubber (SBR) to determine its solubility parameters. Although these two materials possess different solubility parameters, it was possible to bridge this gap by employing a binary mixture. The solvent casting approach followed by hot pressing was chosen as a suitable method to obtain thermally conductive SBR/BNNT composites. The resulting nanocomposites showed up to 35% of improvement in thermal conductivity and a 235% increase in storage modulus in the frequency sweep, when a BNNT loading of 10 wt% was used. However, the viscoelastic properties in the amplitude sweep showed a negative effect with the increase in BNNT loading. A good balance in thermal conductivity and viscoelastic properties was obtained for the composite at a BNNT loading of 5 wt%. [ABSTRACT FROM AUTHOR]

The electronic structures and optical properties of (6,0) single-walled boron nitride (BN) nano-tubes, Cr - doped, Ag - doped and Cr - 0 co - doped BN nanotubes were calculated based on the first principles plane wave ultrasoft pseudopotential method. The results show that the band gaps of Cr - doped and Cr - 0 co - doped systems are smaller than that of the intrinsic system, and the bottoms of the conduction band of the two doped systems pass through the Fermi level, thus realizing the n-type doping of BN nanotubes. The p-type doping of BN nanotubes is realized by Ag doping. The static dielectric constants of the intrinsic BN nanotubes, Ag - doped, Cr - doped and Cr - 0 co - doped BN nanotubes are 1. 17, 1. 61, 1. 32 and 1. 48, respectively, suggesting that the dielectric constants of doping BN nanotubes are larger than that of the intrinsic one. [ABSTRACT FROM AUTHOR]

In accordance with the EU RoHS Directive, the use of Sn–3 mass%Ag–0.5 mass%Cu lead-free solder (SAC305) has become the standard in the manufacturing of electronics. Since SAC305 contains more tin than the conventional tin-lead eutectic solder, erosion of the Fe plating frequently occurs on a hand soldering iron tip and a point soldering machine nozzle. In this study, to extend the life of the Fe plating layer, we investigated the applicability of a composite plating in which Fe is combined with the boron nitride (BN) compounds. We used BN particles as the bulk material, and boron nitride nanotubes (BNNT) as a nanomaterial, to fabricate the regarded composite materials. A solderability test and an erosion resistance test were conducted on the composite plating layer, made of both Fe-BN particles and Fe-BNNTs composites. In the solderability test, the spreading factor of SAC305 on the Fe-BN particle and on the Fe-BNNT composite platings were about the same as, or a little decreased compared to, that of the bare Fe plating. The SAC305 solder was not repelled by either composite plating. In the erosion resistance test, the Fe-BNNT composite plating performed the best, and had the lowest erosion depth. The erosion depths of the Fe-BN particle composite plating and the Fe plating ranged from about 6 to 24 times greater, respectively, than those of the Fe-BNNT composite plating layer, confirming that, in a nanomaterial BNNT-base, composite diffusion of Fe into SAC 305 can be suppressed. [ABSTRACT FROM AUTHOR]

Lowering the synthesis temperature of boron nitride nanotubes (BNNTs) is crucial for their development. The primary reason for adopting a high temperature is to enable the effective activation of high-melting-point solid boron. In this study, we developed a novel approach for efficiently activating boron by introducing alkali metal compounds into the conventional MgO-B system. This approach can be adopted to form various low-melting-point AM-Mg-B-O growth systems. These growth systems have improved catalytic capability and reactivity even under low-temperature conditions, facilitating the synthesis of BNNTs at temperatures as low as 850 °C. In addition, molecular dynamics simulations based on density functional theory theoretically demonstrate that the systems maintain a liquid state at low temperatures and interact with N atoms to form BN chains. These findings offer novel insights into the design of boron activation and are expected to facilitate research on the low-temperature synthesis of BNNTs., (© 2024. The Author(s).)

The inherent properties of boron nitride nanotubes (BNNTs) can be further enhanced through the control of their anisotropy. In particular, horizontally aligned BNNTs (HABNNTs) exhibit considerable potential for various applications. However, directly synthesizing HABNNTs is difficult owing to the random floating of BNNTs and the absence of directional forces. Here, we employed a simple, efficient, and universal "surface-like growth" strategy to synthesize high-density and high-quality HABNNTs in the W 2 B 5 /Zn precursor system. First, the floating range of BNNTs was restricted to the vicinity of the precursor, and then, directional forces were applied to induce BNNT directional growth along the substrate surface. Experiments and simulations confirmed that the HABNNT orientation could be controlled through manipulation of the directional forces. Furthermore, the strategy was employed for HABNNTs synthesis using the MoB 2 /Zn, further demonstrating the universality of the approach. Overall, this work offers a fresh perspective on the synthesis of HABNNTs, further expanding their potential applications.

Abstract Boron nitride nanotubes (BNNTs) are simultaneously isolated and dispersed in organic solvents using a non‐aromatic and highly flexible polymer ethyl cellulose (EC). The colloidal dispersion containing individualized EC‐wrapped BNNTs is stabilized via non‐covalent functionalization through CH‐π and OH‐π interactions between EC and BNNTs. FESEM, TEM, UV‐VIS, FT‐IR, and TG analyses confirm the efficiency of using a simplified and less destructive method without prior heat treatment to enhance the purity and dispersibility of BNNTs in our designed system. This provides a practical approach to the purification and dispersion of BNNTs from a bulk‐produced source, for the fabrication of materials that require large amount of high‐quality BNNTs.

Poly(lactic acid) (PLA) is a well-known biodegradable and biocompatible polymer. However, its poor crystallization ability restricts its broad applications. In this work, PLA/boron nitride nanotubes (BNNTs) nanocomposites were prepared by melt mixing. From either the melt or the glassy state, the effect of BNNTs on the nonisothermal and isothermal crystallization behavior of PLA was investigated by using differential scanning calorimetry (DSC) as well as polarized optical microscopy (POM). It was found that a small amount (0.25 wt%) of BNNTs could enhance both nonisothermal melt and cold crystallization of PLA remarkably. The Avrami equation was employed to analyze the calorimetric characterization of the isothermal crystallization behavior. It was found that the Avrami exponent of PLA crystallization was almost not changed in the presence of BNNTs, suggesting that both the melt and cold crystallization mechanism is unchanged with the addition of BNNTs. This investigation reveals that BNNTs are effective nucleator of PLA in substituting for carbon nanotubes (CNTs), when colorless products are demanded. [ABSTRACT FROM AUTHOR]

Boron nitride nanotubes (BNNTs) are an exciting class of nanomaterials due to their unique chemical and physical characteristics. In recent decades, BNNTs have gained huge attention in research and development for various applications, including as nano-fillers for composites, semiconductor devices, hydrogen storage, and as an emerging material in biomedical and tissue engineering applications. However, the toxicity of BNNTs is not clear, and the biocompatibility is not proven yet. In this review, the role of BNNTs in biocompatibility studies is assessed in terms of their characteristics: cell viability, proliferation, therapeutic outcomes, and genotoxicity, which are vital elements for their prospective use in biomedical applications. A systematic review was conducted utilising the databases Scopus and Web of Science (WOS) (2008–2022). Additional findings were discovered manually by snowballing the reference lists of appropriate reviews. Only English-language articles were included. Finally, the significant analysis and discussion of the chosen articles are presented. [ABSTRACT FROM AUTHOR]

Highly crystalline and few-walled boron nitride nanotubes (BNNTs) had been synthesized by laser ablation using only ammonia borane as a precursor. As a molecular precursor, ammonia borane supplied both B and N atoms with a ratio of 1:1, and BNNTs were formed via the homogeneous nucleation of BN radicals, not the growth from boron nano-droplets, which is a generally accepted growth mechanism of the laser-grown BNNTs. Owing to the absence of amorphous boron impurities, the van der Waals interaction among BNNTs became effective and thus a BNNT fibers was formed spontaneously during the BNNT synthesis. The BNNT growth and the subsequent fiber formation are found to occur only at high pressures of a surrounding gas. The mechanism behind the critical role of pressure was elucidated from the perspective of reaction kinetics and thermal fluid behaviors. A polarized Raman study confirmed that the BNNT fiber formed exhibits a good alignment of BNNTs, which implies great potential for continuous production of high-quality BNNT fibers for various applications. [ABSTRACT FROM AUTHOR]

In recent years, the thermoelectric properties of one‐dimensional boron nitride nanomaterials have gradually attracted widespread attention of researchers in the world. In this paper, boron carbon nitrogen based composite nanofiber films were prepared by electrospinning. It is found that the diameter of nanofibers decreases in BCNNTs/PVA/PEDOT composite films when electrospinning voltage rises, while diameter increases as PVA and BCNNTs concentration increase of electrospinning precursor solution. Finally, thermoelectric power factor is investigated of the composite nanofiber films. It is verified that thermoelectric properties of the films closely related to electrospinning quality. However, fiber density of single‐layer BCNNTs/PVA/PEDOT nanofiber film is too low, folding increase the density and thickness of multilayer BCNNTs/PVA/PEDOT nanocomposite fiber films, and the thermoelectric characteristics are significantly improved. The Seebeck coefficient can reach 3.62 mV/K and the power factor is 29.09 nW/mK2. [ABSTRACT FROM AUTHOR]

An in-situ growth of icosahedral (IC) Pd nanoparticles (NPs) on boron nitride nanotubes (BNNTs) is explored with an external surfactant and reducing agent-free strategy. The IC-Pd@BNNT catalysts show an ultrahigh current density of over − 1000 mA cm−2 with a low overpotential of 199 mV for the hydrogen evolution reaction (HER). At − 20 mA cm−2, the overpotential was as low as 15.7 mV in an acidic medium, which is superior than commercial Pd/C (62.6 mV), and Pt/C (29.4 mV). Moreover, the HER activity of the IC-Pd@BNNT catalysts is maintained even after an accelerated durability test of 40,000 cycles, indicating that the BNNTs are served as a durable support, maintaining the structural integrity of the catalyst. Density functional theory (DFT) calculations confirm that the IC-Pd on the BNNT support with vacancy defects is highly stable and HER active. From the Gas chromatography H 2 gas was quantified, and the Faradaic efficiency was achieved to 98.96%. [Display omitted] • Experimentally proved the defect site BNNT as an electrochemical support for HER. • The IC-Pd@BNNT catalyst show an ultrahigh current density of over − 1000 mA cm−2 • The overpotential is superior 15.7 mV in an acidic medium at − 20 mA cm−2 • The IC-Pd@BNNT catalyst also exhibited high durability over 40000 cycles. • DFT calculations confirm that the V9-Pd 13 -BNNT is the highly active site for HER. [ABSTRACT FROM AUTHOR]

Carbon/boron nitride heteronanotubes are now at the centre of experimental and theoretical studies because of their tunable properties and diverse applications. Herein, we investigate the charge transport and optical properties of carbon/boron nitride hybrid single- and double-walled nanotubes on the basis of first-principles calculations. Our results reveal that the C/BN heterojunctions with radial junctions parallel (horizontal) to the tube axis have more effects than the perpendicular (vertical) junctions on the charge transport properties of heteronanotubes. Furthermore, we find that the nonlinear optical response can be meaningfully controlled by altering the C/BN content and junction arrangement. In double-walled coaxial heteronanotubes, the interwall interaction is also found to increase the electron and hole transport rates noticeably and to have a major effect on the first hyperpolarizabilities of C/BN heteronanotubes. In contrast with coaxial carbon nanotubes, where the inner constituent is totally shielded by the outer tube, in our studied C/BN coaxial heteronanotubes, the inner shell is only partially shielded by the outer constituent. This study suggests a strategy to high-efficient design heteronanotubes with high charge transport properties and tunable nonlinear optical responses. Moreover, the designed C/BN heteronanotubes can discrete electrons and holes, suggesting their application in solar cell materials. [ABSTRACT FROM AUTHOR]