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The present study investigates the interaction between two alkylating agent drugs, cyclophosphamide (CP) and mechlorethamine (MC), with Single-Wall carbon nanotubes (SWCNTs) and Boron Nitride nanotubes (BNNTs). Calculations have been performed by using methods of quantum mechanics and molecular mechanics. The effects of different solvents on the interaction of CP and MC with SWCNTs and BNNTs within the Onsager self-consistent reaction field (SCRF) model, as well as the effects of temperature on the stability of the interactions between the compounds in various solvents have been investigated. Thermodynamic parameters, Frontier Molecular Orbitals (FMOs), and Total Density of States (DOS) of the title compounds have been evaluated by using theoretical calculations. Moreover, the interaction of CP and MC with SWCNTs and BNNTs have been examined through AMBER, OPLS, CHARMM, and MM+ force fields through the molecular mechanic (MM) method. The Monte Carlo simulation of CP and MC structures connected to carbon and boron nitride nanotubes in Water, Methanol, Ethanol, DMSO, and Chloroform solvents showed that Chloroform is the most stable solvent for simulation with the lowest energy, which is directly attributed to dielectric constant. Studies show that the results of Monte Carlo, molecular mechanics, and quantum mechanics are consistent with each other in terms of thermodynamic properties and conformer populations. [ABSTRACT FROM AUTHOR]

We have created a new state of BN (named Q-BN) through rapid melting and super undercooling and quenching by using nanosecond laser pulses. Phase pure c-BN is formed either by direct quenching of super undercooled liquid or by nucleation and growth from Q-BN. Thus, a direct conversion of hexagonal boron nitride (h-BN) into phase-pure cubic boron nitride (c-BN) is achieved by nanosecond pulsed laser melting at ambient temperatures and atmospheric pressure in air. According to the P-T phase diagram, the transformation from h-BN into c-BN under equilibrium processing can occur only at high temperatures and pressures, as the hBN-cBN-Liquid triple point is at 3500 K/9.5 GPa or 3700 K/7.0 GPa with a recent theoretical refinement. Using nonequilibrium nanosecond laser melting, we have created super undercooled state and shifted this triple point to as low as 2800K and atmospheric pressure. The rapid quenching from super undercooled state leads to the formation of a new phase, named as Q-BN. We present detailed characterization of Q-BN and c-BN layers by using Raman spectroscopy, high-resolution scanning electron microscopy, electron-back-scatter diffraction, high-resolution TEM, and electron energy loss spectroscopy, and discuss the mechanism of formation of nanodots, nanoneedles, microneedles, and singlecrystal c-BN on sapphire substrate. We have also deposited diamond by pulsed laser deposition of carbon on c-BN and created c-BN/diamond heterostructures, where c-BN acts as a template for epitaxial diamond growth. We discuss the mechanism of epitaxial c-BN and diamond growth on lattice matching c-BN template under pulsed laser evaporation of amorphous carbon, and the impact of this discovery on a variety of applications. [ABSTRACT FROM AUTHOR]

Introducing ferromagnetism in light-element materials that contain only s and p electrons has captured much attention for their possible application in spintronic devices. In this study, we explored the ferromagnetic properties of carbon-doped boron nitride (B C N) nanosheets obtained by high-temperature annealing of a stacked mixture of boron nitride nanosheets (BNNSs) and graphene prepared by urea-assisted aqueous exfoliation. Three types of BCN nanosheets, referred to as BCN (1:1), BCN (1:2) and BCN (1:3), were successfully synthesized through multistep processes. Strong ferromagnetic responses were observed in the BCN nanosheets with a saturation magnetization of 0.142 emu/g at room temperature. It was found that the thickness of the precursors plays a critical role in the determination of the ferromagnetic properties of the BCN nanosheets. Our results provide a new possibility for the manipulation of ferromagnetism in light-element systems. • Alloy of boron nitride nanosheet and graphene was synthesized by a facile and scalable way. • Ferromagnetism at room temperature was observed. • The saturation magnetization was dependent on the composition and layer thickness of precursors. • Atomic resolution TEM, EELS, XRD, XPS and ICP analyses are provided to confirm the origin of the ferromagnetism. [ABSTRACT FROM AUTHOR]

One dimensional boron nitride (BN) nanomaterials with a high aspect ratio are of great interest due to their unique properties and potential applications. However, BN nanomaterials are generally difficult to synthesize. Here, we describe the creation of arrays of vertically aligned pure BN nanofibers and BN coated carbon nanofibers, fabricated on-chip via a straightforward template-assisted chemical conversion reaction. The template, a glassy carbon nanofiber array, is produced by plasma processing of conventional photoresists. The method is highly controllable, patternable, and scalable, and the final arrays can be fabricated over large areas with a controlled fiber length. We characterize the electron field emission properties of the BN-coated carbon nanofiber array and find a large field enhancement factor, low turn-on voltage, and good stability. The outstanding field emission performance results from the small tip size and high aspect ratio of the nanofiber as well as the high chemical stability and high thermal conductivity of the BN coating. [ABSTRACT FROM AUTHOR]

Here, we report on the large-area synthesis of hBN layer at a comparatively lower temperature using ammonia borane as precursor by microwave assisted surface wave plasma (MW-SWP) chemical vapour deposition (CVD). The solid precursor was sublimed inside the CVD chamber and decomposed to form plasma radicals, which allowed the growth of hBN layer at a lower temperature (∼500 °C). The growth of hBN on Cu catalyst and Si wafer was confirmed by X-ray photoelectron spectroscopy, ultraviolet absorption spectroscopy, Fourier-transform infrared spectroscopy and transmission electron microscopy analysis. The hBN film synthesized on Cu catalyst showed a sharp absorption peak at 276 nm wavelength corresponding to an optical band gap of ∼4.1 eV, owing to the incorporation of carbon and oxygen doping impurities. The reduction of optical band gap of the hBN film with impurity doping can be significant to tune its optoelectronic properties. Thus, the demonstrated MW-SWP-CVD process can be significant to synthesize hBN layers independent of the catalytic behaviour of the substrate, thereby opening enormous possibilities of transfer-free application for device fabrication and as transparent coating on various surfaces. [ABSTRACT FROM AUTHOR]

We explore the photoluminescence (PL) properties of hexagonal boron nitride (h-BN) quantum emitters embedded within atomically thin graphene/h-BN heterostructures fabricated by mechanical transfer. Stable light emission could be observed from h-BN emitters which due to the local presence of multilayer h-BN are not subject to fluorescence quenching by graphene. By using graphene as a top gate contact, the PL emission can be tuned by up to 24 meV per V/nm, with a high robustness of the emitters over several voltage sweep cycles. Two different types of h-BN emitters were observed, one with a quadratic and the other one with a linear Stark shift. Moreover, the vertical electric field leads to an asymmetric modulation of both the fluorescence intensity and lifetime between the negative and positive gate voltage regimes. The overall behavior can be well explained by a model involving different rates for electron and hole tunneling between the h-BN and graphene layers. Our findings suggest ultrathin van der Waals heterostructures as valuable platforms for fine tuning the optoelectronic properties of atomic defect-based quantum emitters. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • B doped TiO 2 SiO 2 /CoFe 2 O 4 was a noble modifier for preparation of self-cleaning PES NF membrane. • High recovery of membrane performance after fouling confirmed their self-cleaning ability. • The used NPs could degrade the adsorbed organic foulants on the membrane surface. • The hydrophilic membrane surface improved antifouling property and reusability of the membranes. Abstract Novel self-cleaning PES nanofiltration membranes were successfully synthesized via the phase inversion method with different amounts of the boron doped-TiO 2 SiO 2 cobalt ferrite (B-TiO 2 SiO 2 /CoFe 2 O 4) nanophotocatalyst. The nanofiltration performance was investigated by the rejection of direct red 16 and COD removal of the biologically treated palm oil mill effluent (POME). The addition of the B-TiO 2 SiO 2 /CoFe 2 O 4 nanoparticles into the polymeric casting solution improved porosity, morphology, structure, pure water flux (PWF), antifouling properties and separation performance of the embedded membranes due to hydrophilic behavior and photocatalytic properties of the B-TiO 2 SiO 2 /CoFe 2 O 4 nanoparticles. The B-TiO 2 SiO 2 /CoFe 2 O 4 nanoparticles can degrade adsorbed organic foulants on the membrane surface (reversible fouling) or deposited/trapped fouling agents into the membrane pores (irreversible fouling). The prevention of the interaction between organic foulant and hydrophilic membrane improves antifouling properties and wettability of the modified membranes. The membrane with 0.5 wt% of the B-TiO 2 SiO 2 /CoFe 2 O 4 nanoparticle had the highest pure water flux and flux recovery ratio (FRR) with the best separation performance. However, at high concentration of nanoparticles, agglomeration of the nanoparticles on membrane surface/pores resulted in pore blocking, roughness membrane surface which led to slightly reduction of PWF, FRR and separation performance. The obtained results were also confirmed by contact angle measurement, scanning electron microscopy (SEM) and atomic force microscopy analysis (AFM). [ABSTRACT FROM AUTHOR]

Abstract Influence of carbon nanotubes (CNT), hexagonal boron nitride (h-BN) and tungsten carbide (WC) nano-reinforcement on the mechanical and tribological properties of the Cu-Ni binder alloy was investigated experimentally and numerically. In situ TEM and multiscale micromechanical finite element (FE) modeling were used to study the mechanisms of deformation of the nanomodified binder. Сomplex reinforcement by 0.1% CNT + 0.1% hBN + 0.69% WC increases the tensile strength of the materials from 155 to 346 MPa, bending strength from 420 to 832 MPs, hardness from 2.1 to 2.4 GPa and elastic modulus from 98 to 123 GPa. The complex reinforcement changes the wear mechanism and significantly enhanced the tribological properties of the binders, decreasing the coefficient of friction from 0.47 to 0.28 and wear rate from 12.3 to 6.7·10−6 mm3/N/m. The failure of the nanomodified binder was found to be caused by the emergence and propagation of microcracks along the interface between hBN particles and the matrix. Carbon nanotubes inhibit the propagation of cracks, significantly increasing the mechanical and tribological properties of Cu-Ni binders. [ABSTRACT FROM AUTHOR]

Abstract Magnesium diboride as a precursor with dual role of Nitrogen introduces a simple “decomposition-adsorption-deposition (DAD)” technique for the synthesis of Hexagonal Boron nitride microsheets (BNMSs) on silicon (Si) substrate at 1100 °C. The synthesized BNMSs has the apparent morphology like the white dispersed feathers on a plate surface with diameter in the range of 3–15 µm and lengt greater than 30 µm. All the BNMSs has the characteristics of h -BN lattice with an interlayer spacing of 0.34 nm. Boron and Nitrogen elemental compositions and h -BN phase of the synthesized BNMSs are verified from its characterization by X-ray photoelectron spectroscopy (XPS), Fourier transformed infrared (FTIR) spectroscopy and Raman. [ABSTRACT FROM AUTHOR]

Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide. [ABSTRACT FROM AUTHOR]

Sustainable utilisation of solid waste has been influenced by the increasing population of the world. Benefits of using solid waste based on natural fibre in polymer material are biodegradability and cost effectiveness. In poultry farms, chicken poultry, one of the slaughterhouse wastes is confronted with 30 106 kg of waste per year in Turkey. The evaluation of this waste, which is quite rich in keratin, is extremely important both for the solution of the waste problem and for maintaining a clean environment, bringing this valuable material to the economy. These fibres are stable, durable and biodegradable because they have a crystalline structure. However, this valuable waste will have a positive effect when used together with boron minerals, which both increase the mechanical properties, flame retardancy and biodegradation of composite material. In this study, it is the aim to manufacture superior polyester-based composite materials reinforced with three kinds of boron minerals, such as boron oxide, borax pentahydrate, borax decahydrate and fibres recycled from waste chicken feathers. The effect of different filling ratios of filling materials on the mechanical and physical properties of composite materials was examined. Flame retardancy properties of the composites with best mechanical results were investigated. After pouring by means of the pre-casting process, the water absorption and swelling thickness of final products, as well as density, bending strength, flexural modulus, limiting oxygen index, thermogravimetric analysis and scanning electron microscope analysis, was performed. Mixing prescriptions and conditions with the best properties were determined. [ABSTRACT FROM AUTHOR]

Carbon nanotube/Boron nitride(CNT/BN) nanocomposites were performed by a facile method with boric acid (H 3 BO 3 ) and melamine (C 3 H 6 N 6 ). Uniform boron nitride (BN) precursor deposition films were deposited onto the surface of multiwall carbon nanotubes (MWCNTs),which involves attachment of the precursor and subsequent nitridation in ammonia atmosphere at 1050 °C. The qualitative and quantitative analysis of X-ray diffraction (XRD) on the crystal structure and phase composition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to characterize the material surface morphology and coating structure. Chemical composition analysis of surface and chemical bonds formed by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared Spectroscopy (FTIR) confirmed as well as the oxidation resistance under high temperature by thermal gravimetric analysis and differential thermal analysis (TG-DTA). The results indicate that the boron nitride coating on carbon nanotubes composite has been synthesized successfully by this method and greatly improves the antioxidant performance of carbon nanotubes compared with the original carbon nanotubes (690 °C, compared to 550 °C of original carbon nanotubes), which provides a potential application at high temperatures for carbon nanotube materials. [ABSTRACT FROM AUTHOR]

Abstract: Emulsion detonation synthesis (EDS) is a newly developed process to synthesize nano‐sized ceramic powders based on the detonation of 2 water‐in‐oil emulsions. The process provides high pressure and temperature along with rapid quenching. In this work, we report the formation of wurtzite phase BN (w‐BN) for the first time by EDS process, using hexagonal BN (h‐BN) as the precursor. Characterization studies demonstrated the formation of w‐BN with sizes varying from nanometer to micrometer scale either embedded in or grown from h‐BN matrix. These findings provide a new avenue to synthesize metastable and superhard BN phases. [ABSTRACT FROM AUTHOR]

Defect-related deep-level emissions at ∼4 eV from hexagonal boron nitride (h-BN) have been extensively investigated during the past decades. Although the emission has often been associated with deep level impurities such as carbon and oxygen, the structural and chemical origins of the emission center have not yet been identified. Here, we perform systematic photoluminescence measurements and quantitative trace impurity analysis of variously heat-treated h-BN samples with different deep-level emission intensities. In contrast to the common belief, no positive correlation between the impurity (carbon and oxygen) concentration and the deep-level emission intensity was found. We also demonstrate that the intensity of the deep-level emission is significantly enhanced by high-temperature heating (∼1900 °C) under an N2 environment and subsequent post-annealing at ∼900 °C. These results suggest that intrinsic defects created under N2-rich conditions are responsible for the deep-level emission. Furthermore, we found that besides the well-recognized zero-phonon line (ZPL) at ∼4.1 eV, additional ZPLs are induced in the near ultraviolet (NUV) region by appropriate annealing of the N2-treated h-BN sample. The results of temperature-dependent and time-resolved PL measurements on these NUV emission bands are given and discussed. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) has been used to study the surface interactions of pristine, Ni- and Pt-doped (4,4), (5,5), (7,7) and (8,8) boron nitride nanotubes (BNNTs) with ammonia (NH 3 ) molecules. To verify the impact of external electric field (EF) on the surface interactions between the nanotubes and adsorbed NH 3 molecules, in this work, the NH 3 /(4,4) BNNTs adsorbed complex system under an applied EF with strength of 3 × 10 −2  a.u. and 4 × 10 −2  a.u., along the z axis (perpendicular to the tube axis) has been investigated. It was shown that after doping of Ni and Pt atoms, the primary symmetry of BNNTs was decreased, enhancing the chemical activity of BNNTs towards NH 3 molecules and subsequent resulting in dramatic changes of their electronic properties. Our overall results indicated that, in addition to the Ni and Pt doping, the applied external EF could enhance the sensitivity of BNNTs toward NH 3 molecule, which can be considered as a new strategy of sensor fabrication. [ABSTRACT FROM AUTHOR]

Pyrolytic boron nitride (PBN) plates were synthesized by chemical vapor deposition (CVD) with temperatures of 900–1900 °C and total pressures of 50–1000 Pa on graphite by using borazine as the precursor. The effects of temperature and pressure on the micromorphology and crystal structure of the PBN were investigated. The as-deposited PBN possessed three typical types of micromorphologies depending on the deposition condition. PBN with dense and laminated structure (Type A) were deposited at temperatures of 1150–1900 °C with relative low pressures of 50–200 Pa, and PBN with porous and isotropic structure (Type C) was deposited at temperatures above 1100 °C with higher pressures above 250 Pa. PBN with dense and glass-like fracture structure (Type B) was obtained at the other range of the deposition condition. The interlayer spacing ( d (002) ) and the preferred orientation ( PO ) of the crystallite were calculated by using XRD data of the PBN plates. The degree of the preferred orientation tended to be higher with the increase of temperature and decrease of pressure, and higher temperature led to smaller value of d (002). The crystal growth mechanism of the three types of PBN was discussed. [ABSTRACT FROM AUTHOR]

Reliable and controllable synthesis of two-dimensional (2D) hexagonal boron nitride (h-BN) layers is highly desirable for their applications as 2D dielectric and wide bandgap semiconductors. In this work, we demonstrate that the dissolution of carbon into cobalt (Co) and nickel (Ni) substrates can facilitate the growth of h-BN and attain large-area 2D homogeneity. The morphology of the h-BN film can be controlled from 2D layer-plus-3D islands to homogeneous 2D few-layers by tuning the carbon interstitial concentration in the Co substrate through a carburization process prior to the h-BN growth step. Comprehensive characterizations were performed to evaluate structural, electrical, optical, and dielectric properties of these samples. Single-crystal h-BN flakes with an edge length of ~600 µm were demonstrated on carburized Ni. An average breakdown electric field of 9 MV/cm was achieved for an as-grown continuous 3-layer h-BN on carburized Co. Density functional theory calculations reveal that the interstitial carbon atoms can increase the adsorption energy of B and N atoms on the Co(111) surface and decrease the diffusion activation energy and, in turn, promote the nucleation and growth of 2D h-BN. [ABSTRACT FROM AUTHOR]

Three [2]ferrocenophanes equipped with unsaturated BN moieties at bridging positions were synthesized and structurally characterized. As revealed by DFT calculations, these first examples of azabora[2]ferrocenophanes are similarly strained to the well-known Me2Si-bridged [1]ferrocenophane. [ABSTRACT FROM AUTHOR]

The first-principles calculations based on spin-polarized density functional theory is carried out to investigate the structural, electronic and magnetic properties of a hexagonal boron nitride sheet (h-BNS) doped by one or two lithium atom(s). Moreover, a vacancy in the neighborhood of one Li-substituted atom is introduced into the system. All optimized structures indicate significant local deformations with Li atom(s) protruded to the exterior of the sheet. The defects considered at N site are energetically more favorable than their counterpart structures at B site. The spin-polarized impurity states appear within the bandgap region of the pristine h-BNS, which lead to a spontaneous magnetization with the largest magnetic moments of about 2 μ B in where a single or two B atom(s) are replaced by Li atom(s). Furthermore, the Li substitution for a single B atom increases the density of holes compared to that of electrons forming a p-type semiconductor. More interestingly, the structure in which two Li are substituted two neighboring B atoms appears to show desired half-metallic behavior that may be applicable in spintronic. The results provide a way to enhance the conductivity and magnetism of the pristine h-BNS for potential applications in BN-based nanoscale devices. [ABSTRACT FROM AUTHOR]

Water transport across nanoscale channel is of great interest in biology, geology, and materials science. The boron nitride nanotubes (BNNTs) with different charge distributions were employed as a model to investigate the water transport in nanoscale channel through molecular dynamics simulations. It is found that the transport of water could influenced by the charge regulation in the terminal of BNNTs. If the diameter of BNNTs is small, the water permeation in charge-tunable BNNT(6,6) are mainly determined by transportation dynamics of water molecules located around the entrance and exit due to trap phenomenon. The trap phenomenon would be weaken with the increase of BNNTs' diameter, and the dynamics of water transportation through the BNNTs would be speeded up owing to the enhanced effect caused by the directional electric field and the relatively larger pore channel. [ABSTRACT FROM AUTHOR]

Current study provides a comprehensive numerical investigation of the peristaltic transport of boron nitride-ethylene glycol nanofluid through a symmetric channel in presence of magnetic field. Significant effects of Brownian motion and thermophoresis have been included in the energy equation. Hall and Ohmic heating effects are also taken into consideration. Resulting system of non-linear equations is solved numerically using NDSolve in Mathematica. Expressions for velocity, temperature, concentration and streamlines are derived and plotted under the assumption of long wavelength and low Reynolds number. Influence of various parameters on heat and mass transfer rates have been discussed with the help of bar charts. [ABSTRACT FROM AUTHOR]

Boron nitride nanosheets (BNNSs) are a structural analogue of graphene that are thought to exhibit good tribological performances, due to their typical laminated structure. However, the tribological properties of pure solid BNNSs have not been thoroughly researched, which may be resulted from the lack of knowledge regarding the synthesis of this special two-dimensional (2D) material. In this work, BNNSs were deposited on silicon wafers via nitridation of magnesium diboride (MgB 2 ) in a chemical vapor deposition system. The ammonia (NH 3 ) was used as the nitrogen source. The tribological behaviors of the synthesized BNNSs, including friction and wear resistance, were evaluated with a CSM tribometer. The results indicated that the BNNSs can decrease the friction of bare silicon wafer. The average value of the friction coefficients had no obvious change with the changes in load and frequency. The wear rate increased when the load and frequency increased. The results suggested that the BNNSs had good potential applications in industrial lubrication, after they were modified by small molecules or polymers. [ABSTRACT FROM AUTHOR]

In this study, silicon nitride (Si 3 N 4 ) ceramics added with and without boron nitride nanotubes (BNNTs) were fabricated by hot-pressing method. The influence of sintering temperature and BNNTs content on the microstructures and mechanical properties of Si 3 N 4 ceramics were investigated. It was found that both flexural strength and fracture toughness of Si 3 N 4 were improved when sintering temperature increases. Moreover, α-Si 3 N 4 phase could transform into β-Si 3 N 4 phase completely when sintering temperature rises to 1800 °C and above. BNNTs can enhance the fracture toughness of Si 3 N 4 dramatically, which increases from 7.2 MPa m 1/2 (no BNNTs) to 10.4 MPa m 1/2 (0.8 wt% BNNTs). However, excessive addition of BNNTs would reduce the fracture toughness of Si 3 N 4 . Meanwhile, the flexural strength and relative density of Si 3 N 4 decreased slightly when BNNTs were added. The related toughening mechanism was also discussed. [ABSTRACT FROM AUTHOR]

A novel compressive boron nitride (h-BN) based seal has been developed for planar intermediate temperature solid oxide fuel cell (SOFC). It exhibited extremely low leakage rates and thermal cycling stability under simulated stack conditions. The h-BN based seal showed leakage rates of 0.01 sccm/cm under gas pressure of 6.8 kPa in the temperature range of 650–800 °C, and maintained similar leakage rates during 10 thermal cycles. The excellent sealing performance can be explained by oxidation of h-BN surface to form liquid B 2 O 3 layers beyond the critical temperature of 700 °C. Two of compliant B 2 O 3 glass layers were observed on the surface of the h-BN to adjoin well cell and metallic interconnect. The sandwich structure with liquid B 2 O 3 layer on two sides of the h-BN seal could not only enhance interfacial adherence but also eliminate the gas leakage paths at SOFC operation temperature. The applicability of the h-BN based seal has also been verified by single cell test. [ABSTRACT FROM AUTHOR]

Introducing C–B diatomic groups in carbon-doped hexagonal boron nitride (h-BN) flakes resulted in high activity and selectivity for HCOOH in CO2 electroreduction. The activation of CO2 was prone to occur on B atoms while the activation of the proton occurred on C atoms. The volcano-type relation of Faradaic efficiency for HCOOH production over carbon content originates from the balance of H* and COOH* intermediates in carbon-doped h-BN catalysts. [ABSTRACT FROM AUTHOR]

A simple one-step method for the fabrication of Boron Carbon Nitride (BCN) nanosheets at a temperature of 580 °C was developed. Boric anhydride, urea and melamine precursors were thermally condensed in the nitrogen atmosphere. The optical band gap of BCN was estimated to be 3.01 eV, resembling a typical wide bandgap semiconductor. XPS peaks revealed that B, C and N atoms are bound together by B N, B C and C N bonds. The Photodegradation of Cibacron yellow FN-2R dye by BCN was evaluated under UV irradiation and the results were compared with the C 3 N 4 . The active species involved in the reaction was studied using radical scavengers. The toxicity of the photocatalyst before and after degradation was determined using CArtemia salina’s nauplii and certain bacterial species. Facile synthesis, high stability and toxic free against aggregation in water, the as-fabricated metal free BCN nanosheets show promising results in achieving efficient dye degradation. [ABSTRACT FROM AUTHOR]

Commonly prescribed antibiotics are emerged as a new class of water contaminants that impart sever effects on all the living being directly or indirectly. In this study efficient adsorbent i.e. boron nitride (BN) nanomaterials have been explored for the removal of two commonly used fluoroquinolone i.e. ofloxacin (OFL) and moxifloxacin (MOXI) from the water system. Effect of various experimental parameters such as contact time, pH, adsorbent dosage and initial concentration of antibiotics on the percentage of adsorption has also been studied in detail. Furthermore, the best fitted adsorption isotherm among Langmuir and Freundlich isotherms has also been evaluated to demonstrate the nature of adsorption. Subsequently, adsorption studies followed pseudo-second-order kinetic model with sufficiently large values of rate constant compared to the pseudo-first-order kinetic adsorption. From these studies, it has been demonstrated that BN nanomaterials has great potential for the adsorption of antibiotics with large adsorption capacity and superfast adsorption rate. [ABSTRACT FROM AUTHOR]

Emulsion detonation synthesis (EDS) is a recently developed process to synthesize nano-sized ceramics based on detonation of two water-in-oil emulsions. The process produces high pressure and temperature along with fast cooling, thus providing ideal environment for metastable phase formation. Here we applied the process for the first time on hexagonal boron nitride (h-BN). Characterization studies demonstrated the formation of metastable explosion BN phase (e-BN) with grain sizes of 10–20 nm embedded in h-BN matrix. These findings support the potential use of EDS a novel and promising pathway for the synthesis of e-BN and other metastable BN phases. [ABSTRACT FROM AUTHOR]

The synthesis of uniform, highly crystalline thin films of hexagonal boron nitride (h‐BN) is an important step for its applications in multilayered devices with other emerging 2D materials. We report on the growth of high purity h‐BN by reactive magnetron sputtering from a pure B target in an Ar/N2 plasma. Enhanced h‐BN crystallinity on Ni substrates was achieved using a negative DC substrate bias during deposition, which served to increase the energy of incident ions, causing higher adatom mobility and re‐sputtering of weakly bound species on the growth surface. Growth rates between 0.002 to 1.1 Å s−1 were observed as the power was varied from 10 to 200 W and the growth temperature was either room temperature or 850 °C. BN films grown on a r‐sapphire substrate or a silicon (100) wafer with native oxide were smooth but amorphous under all conditions. Crystalline growth was observed on unbiased Ni foil substrates heated to 850 °C provided the growth rate was below 0.01 Å s−1, but the films were a non‐uniform mixture of h‐BN crystals and a disordered phase. Using a −50 V substrate bias, a high degree of h‐BN crystallinity and film homogeneity over large areas on the Ni substrate was achieved. [ABSTRACT FROM AUTHOR]

Unintentionally doped cubic boron nitride (cBN) single crystals with color zoning were investigated by Raman spectroscopy. Besides the TO mode at 1053 cm −1 and the LO mode at 1304 cm −1 , some little vibrational bands at 925 cm −1 , 955 cm −1 and 1247 cm −1 corresponding to the amber regions in the { 1 ¯   1 ¯   1 ¯ } N sectors of cBN crystals were observed. These vibrational bands probably result from the disorder-activated Raman scattering (DARS) due to the high defect densities. It is shown that these defects and impurities are nonuniform, easily formed and incorporated in { 1 ¯   1 ¯   1 ¯ } N growth sectors during the growth process of cBN crystals. These defects and impurities are color centers in cBN, therefore, the cBN crystal exhibits symmetrical color zoning relative to the {111} growth sectors. [ABSTRACT FROM AUTHOR]

Mesoporous monolithic (3D) boron nitride (BN) structures are synthesized using a template-assisted polymer-derived ceramic route. Polyborazylene is selected to impregnate monolithic activated carbon, which is used as template. After pyrolysis and template removal, this method supplies BN compounds with controlled crystallinity and tunable textural properties controlled by the temperature at which they have been annealed (from 1000 to 1450°C). Monoliths with an interconnected mesoporous network, high specific surface areas from 584 to 728 m2 g-1, significant pore volumes from 0.75 to 0.93 cm3 g-1 and a relatively high compressive strength are generated. These highly porous compounds are used as nanoscaffolds to confine ammonia borane (AB). The composites provide an effective gravimetric hydrogen capacity of up to 8.1 wt%, based on AB measured at 100 °C; this value demonstrates the high potential of this system as a safe potential hydrogen storage material. [ABSTRACT FROM AUTHOR]

This study is focused on finding a versatile approach for obtaining low cost, lightweight composites with high thermal conductivity and good mechanical properties at the same time. The most promising application for such material is to replace fabric reinforced laminates in circuit board production. We used high density polyethylene (HDPE) as a polymer matrix and two types of hexagonal boron nitride (hBN) powders with average particle size 2–5 μm and 120–140 nm as a functional filler. To improve both filler-matrix adhesion and mechanical properties of the composites we used one of two techniques: treating the filler with silane coupling agent before composite processing or using titanate coupling agent in the process of roller-mixing. The study showed, that while the best thermal conductivity of 2 W/m K was achieved on the sample prepared without any coupling agent the sample was too brittle for further processing. On the other hand the sample with KR TTS additive and HDPE to hBN ratio 1:1 showed quite high ultimate strength of 24.8 MPa coupled with high Young's modulus, good elongation at break and thermal conductivity of 0.9 W/m K. Usage of hBN nanopowder as a filler resulted in good mechanical properties and high elongation at break values with thermal conductivity values significantly lower than for micro-sized fillers (0.43 W/m K). [ABSTRACT FROM AUTHOR]

A series of “ravine-like” boron carbonitrides (abbreviation: BCN) were synthesized by a green precursor pyrolysis method at different temperatures (about 700–1100 °C). The highest electrochemical performance of BCN-800 (Named BCN-temperature) electrode was observed, because the “ravine-like” structure can significantly increase the contact area and improve the wettability between electrode and electrolyte. The BCN electrode exhibited ultrahigh specific capacitance 805.9 F/g (at a current density of 0.2 A/g), excellent rate capability, and good cycling stability (91%) after 3000 cycles at a current density of 8 A/g, showing high potential applications in supercapacitors. [ABSTRACT FROM AUTHOR]

The spatial densities of valence electrons and their cross sections, the total energies, and the force response on the deformation for modeling objects of the cC-cBN composite were evaluated by methods of the electron density functional and ab initio pseudopotential. The spatial distributions of the electron density of the chemical bonds C B and C N were obtained and discussed. The first principles calculation confirms that the chemical C N bond stronger than the C B bond; it affects the chemical inertness of different composite models. In this computer experiment, the imaginary indenter penetration process is simulated as the gradual relocation of atoms deep into the cluster. When the model cubical crystal of the cC-cBN composite with as sequence of layers as C, N, and B was deformed at the top like on figure, the record high hardness and the low reactivity combined. Model crystals of the cC-cBN composite with other order of layers C, N, and B have the high value of hardness too, but electron density, squeezed to the surface of the cluster, casts doubt on the chemical stability. In addition, it was identified physical mechanisms of the hardness of the materials, which have tetrahedral chemical bonds. The maps of the spatial distribution of the electron density of the deformed C N bond illustrated the increasing concentration of electron density along this bond. The changes of the total energy are interpreted as changes of the ionicity degree of deformed bonds in the model clusters. [ABSTRACT FROM AUTHOR]

Polymer composites with high thermal conductivity, low dielectric constant and low dielectric loss are very promising for electronic packaging. However, it is a big challenge to balance these parameters. Herein, we demonstrated the novel thermally conductive and stable silver nanoparticles decorated hexagonal boron nitride (h-BN/AgNPs)/poly(arylene ether nitrile) composites with low dielectric constant and low dielectric loss. To achieve these targets, h-BN was modified by polydopamine through mussel-inspired method, followed by attaching the silver nanoparticles onto h-BN surface. As-modified h-BN was incorporated into PEN matrix to prepare AgNPs/h-BN@ PEN composite films by solution casting method. Owing to the good dispersion of nanofiller and synergistic effect of AgNPs and h-BN, the resultant AgNPs/h-BN@PEN composite with 30 wt% of AgNPs/h-BN exhibited high thermal conductivity of 0.921 W/(mK). Furthermore, the relatively low dielectric constant (5.6) and dielectric loss (0.11) of PEN composites at 1 kHz were achieved with the same loading content of AgNPs/h-BN. In addition, the thermal stability of PEN composites was greatly increased with the incorporation of AgNPs/h-BN. This work demonstrated that the thermally conductive and stable AgNPs/h-BN@PEN composites with low dielectric constant and low dielectric loss can be used as promising packaging materials in the area of electronic packaging. [ABSTRACT FROM AUTHOR]

We herein report in-situ solvothermal method to prepare Fe 3 O 4 nanoparticles-coated porous BN microrods (p-BNMR@Fe 3 O 4 ) nanocomposites. A combination of the XRD, SEM and TEM characterization indicates that the good-crystallinity Fe 3 O 4 nanoparticles with an average size of 7 nm are uniformly coated on the surface of p-BNMRs. The as-prepared p-BNMR@Fe 3 O 4 nanocomposites perform significant adsorption activity for Pb(II), and the maximum adsorption capacity is as high as 249.5 mg/g when the initial concentration of Pb(II) is 180 mg/L at room temperature with pH of 5.5. In addition, the superparamagnetic property of the p-BNMR@Fe 3 O 4 nanocomposites also enabled the rapid separation by a low magnetic field. Consequently, the p-BNMR@Fe 3 O 4 nanocomposites have great potential in treating Pb(II)-contaminated water. [ABSTRACT FROM AUTHOR]

We investigated the interaction of a phosgene molecule with four kinds of BN nanocones with 60°, 120°, 180° and 240° disclination angles using density functional theory calculations. Based on the results, the phosgene molecule tends to be adsorbed on the apex of all BN nanocones with adsorption energies of −11.1, −4.6, −16.6, and −14.8 kcal/mol, respectively. It was predicted that both of low coordination B atom, and B B antiphase defects stabilize the LUMO level of the BN nanocones, and make them more reactive to phosgene gas. The electrical conductivity of the BN nanocone with 60° disclination angle will not change at the presence of the phosgene; and it cannot be used as a sensor. But the electrical conductivity of the BN nanocones with 120°, 180° and 240° disclination angles significantly increases. Therefore, these nanocones may be promising candidates for application in phosgene sensors. We found that the order of electronic sensitivity of the BN nanocones toward the phosgene gas is as follows: BN-240 > BN-120 > BN-180 » BN-60. The recovery time for the BN nanocones with 60°, 120°, 180° and 240° disclination angles is about 4.5 × 10 −5 , 7.8 × 10 −10 , 0.48, and 0.02  s  at 298 K, respectively, indicating that the BN nanocones benefit from a short recovery time as chemical sensors. [ABSTRACT FROM AUTHOR]

We report a new method for few-layer graphene (FLG) preparation via plasma-assisted ball milling with carbide, nitride or oxides as ball-milling media and expandable graphite raw material. Scanning electron microscopy, transmission electron microscopy and Raman spectroscopy were applied to characterize the FLG. FLGs prepared by using different ball-milling media such as boron nitride (BN), tungsten carbide (WC), zinc oxide (ZnO), iron oxide (Fe 2 O 3 ) and germanium oxide (GeO 2 ) were used to determine the relationship between the FLG layer number and inductive capacity of the ball-milling media. Parameters for the synthesis of high-quality FLGs were also optimized. [ABSTRACT FROM AUTHOR]

We grow high-quality two-dimensional hexagonal boron nitride (h-BN) films on copper pockets by chemical vapor deposition. A piece of sapphire embedded in the pocket serves as an oxygen supply during the growth process. To obtain clean h-BN films, source powders are placed in a U-shaped quartz tube and heated up in a water bath without the carrier-gas flow. These films are characterized by using SEM, Raman, XPS, and selected area electron diffraction analyses. As dielectric substrates, h-BN films significantly enhance the charge-carrier mobility of graphene transistors. This facile and robust method can be a scalable approach to synthesize large-area high-quality h-BN films for related electronic applications. [ABSTRACT FROM AUTHOR]

Plasma-assisted molecular beam epitaxy (PA-MBE) is now widely used for the growth of group III-nitrides. Many years ago it became clear that during PA-MBE there is unintentional doping of GaN with boron (B) due to decomposition of the pyrolytic boron nitride (PBN) cavity of the RF plasma source. In this paper we discuss the unintentional B incorporation for PA-MBE growth of GaN and Al x Ga 1−x N using a highly efficient RF plasma source. We have studied a wide range of MBE growth conditions for GaN and Al x Ga 1−x N with growth rates from 0.2 to 3 µm/h, RF powers from 200 to 500 W, different nitrogen flow rates from 1 to 25 sccm and growth times up to several days. The chemical concentrations of B and matrix elements of Al, Ga, N were studied as a functions of depth using secondary ion mass spectrometry (SIMS). We demonstrate that boron incorporation with this highly efficient RF plasma source is approximately 1×10 18 to 3×10 18 cm −3 for the Al x Ga 1−x N growth rates of 2 – 3 µm/h. [ABSTRACT FROM AUTHOR]

The co-dopant, boron nitride (BN) doped graphene (BNG), has been synthesized recently and has been shown to be an efficient method to engineer band gaps in graphene. The control of the dopant domain size allows us to tailor the electronic structure and properties of graphene. We have studied the electronic and optical properties of boron nitride doped graphene with different domain shapes and sizes. Seven different doping configurations (three quantum dot types and four triangular-shaped types, being two with nitrogen and two with boron at the edges, respectively) were chosen and calculated making use of first-principles calculations based on the density functional theory (DFT). Band gap opening has been observed for such structures whose magnitude increases with the doping concentration. We found that only atoms near the dopant boundary make significant contributions to the near Fermi energy. The configurations with triangular-shaped nanodomains with nitrogen and boron at the edge show a different structure of absorption and conductivity peaks when compared with the quantum dot type structures and graphene. Such findings suggest a controllable way of manipulating the optical properties of doped graphene materials. [ABSTRACT FROM AUTHOR]

A facile and effective approach for the preparation of functionalized born nitride quantum dots (BNQDs) with blue fluorescence was explored by the hydrothermal treatment of the mixture of boric acid and melamine at 200 °C for 15 h. The as-prepared BNQDs were characterized by transmission electron microscopy (TEM), high-resolution TEM, atomic force microscopy, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The single layered BNQDs with the average size of 3 nm showed a blue light emission under the illumination of the UV light. The BNQDs could be easily dispersed in an aqueous medium and applied as fluorescent probes for selective detection of Fe3+ with remarkable selectivity and sensitivity (the lowest detection limit was 0.3 µM). The fluorescence fiber imaging demonstrated that the as-prepared quantum dots could be used as a valuable fluorchrome. Therefore, the BNQDs could be envisioned for potential applications in many fields such as biocompatible staining, fluorescent probes, and biological labeling. [ABSTRACT FROM AUTHOR]

Herein, a nanosized Mn oxide/boron nitride composite is reported as a catalyst for water oxidation. This study is interesting because nanosized boron nitride is one of the most stable and inert compounds and can form a new composite with Mn oxides. The composite was synthesized using a straightforward and simple procedure and characterized, showing that the composite is a supported Mn(iii,iv) oxide on boron nitride. The water-oxidizing activity of the composite was studied in the presence of cerium(iv) ammonium nitrate and photoproduced Ru(bpy)33+ as oxidants. The optimized catalyst calcined at 200–300 °C showed a turnover frequency of 0.15 (mmolO2/s−1 molMn−1) in the presence of cerium(iv) ammonium nitrate. [ABSTRACT FROM AUTHOR]

The ultimate objective of chemical conversion is to achieve 100 % selectivity from catalysis, and this is also a prodigious challenge for the conversion of light paraffins into olefins, because it involves controlled activation of highly stable aliphatic C−H bonds. Herein, we show that metal-free boron nitride (BN) nanosheets not only enable the oxidative dehydrogenation of ethane to ethylene exclusively at near 10 % conversion, but they also deliver a remarkable 60 % selectivity at an ethane conversion of 78 % and remain stable over 400 h at 575 °C. Our operando infrared spectroscopy and 18O isotope tracer study explicitly demonstrates that B−O(H) active sites are formed at the edges of BN through the aid of ethane, and the dehydrogenation circle is completed over these B−O sites by the assistance of O2. [ABSTRACT FROM AUTHOR]

In the last decade, few-layer boron nitride nanosheets and monolayer BN nanosheet (BNNS) have gained much attention due to their unique physical and chemical properties. To date, BNNS can be produced by micromechanical cleavage of BN crystal, unzipping BN nanotubes, chemical vapor deposition (CVD), and solution processed exfoliation from bulk BN powder. Due to the low cost and abundance of bulk BN powder and its simple processing for potentially scalable production, great efforts have been devoted toward solution processed exfoliation. In this feature article, recent significant advances in solution processed synthesis of BNNS are summarized. In particular, the solvent choice for one-step BN exfoliation is highlighted. Multi-dimensional assemblies consisting of BNNS are discussed, such as BN fiber, BN paper, and BN aerogel. The emerging applications of BNNS in different fields are then focused on, especially in barrier materials, dielectrics, catalysts, and thermal management. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride ( h-BN) has been explored for lithium intercalation due to its similar crystal structure to graphite, a well-known anode material for Li-ion secondary batteries. Lithium h-BN intercalation compounds (Li-BNICs) have been successfully synthesized through heat treatment. In this study, potential physical properties related to electrical conductivity were investigated using pristine and milled h-BN, which is further mixed/combined with milled graphite. The electrochemical properties were characterized by cyclic voltammetry (CV) and galvanostatic cycling with potential limitation (GCPL). The chemical potential of h-BN was estimated about 1.0 V versus Li/Li + and a two-phase reaction was suggested. Accordingly, Li-BNIC is more stable than Li-GICs (lithium graphite intercalation compounds) in terms of thermal stability. [ABSTRACT FROM AUTHOR]

In this study, Boron Nitride Microtube (BNMT) synthesis was carried out with a catalytic annealing method from amorphous boron powder and nitrogen gas (N2) in the presence of MnO2. Experiments were performed in N2 atmosphere controlled furnace at 1400°C and also at 1/1 weight ratio of B/MnO2 for different time as 2-6 hrs. It was seen that from the results of XRD analysis as the reaction time increases, the crystallinity of h-BN increases. The 6-hour reaction time at which the highest crystal size is obtained with 207 Å is the optimum reaction time for the study. It was understood that from the results of FT-IR analysis as the reaction time increases, the peak areas of the B-N stretching and B-N-B bending vibrations and h-BN formation are increased. Also, it was understood that from the results of FT-IR analysis the optimum reaction time for the study was 6 hours. It was determined that from the results of EDX analysis the atomic ratio 1,03 of B/N is compatible with the chemical stoichiometric ratio (1.00) of the atom B and the atom N of h-BN. It was identified that from the results of SEM analyzes the BNMT's diameters changed from 394 to 633 nm and BNMT's lengths changed from 3,13 to 6,12 μm. From the results of the volumetric pore size distribution it was understood that the synthesized material is in a mesoporous structure consisting of particles having a mean pore radius of 16,997 Å. As a result, it was observed that the reaction efficiency increased as the reaction time increased in the synthesis reaction of BNMTs at 1400°C and the highest reaction efficiency reached to 81,20% after 6 hours reaction time. [ABSTRACT FROM AUTHOR]

The electronic properties of hybrid graphane/boron-nitride nanoribbons with hydrogen vacancies are investigated using density functional calculations. Hydrogen vacancies in the shapes of lines and chains in the composite system are able to alter the electronic properties drastically. If segregated by a BN separator, H-vacancy chains may also be used for conduction of optically excited electrons on either edge of the BN, rendering it possible to create spatially distinctive conduction channels. [ABSTRACT FROM AUTHOR]

The novel boron nitride nanosheet and copper sulfide nanohybrids (BNNS@CuS) were synthesized by a facile solvothermal approach and proposed as a prominent peroxidase-like mimic. Through integrating an intensified colour reaction induced by catalytical oxidation with cholesterol oxidase, the BNNS@CuS was developed for the colorimetric determination of cholesterol with a linear range of 10–100 μM and a detection limit of 2.9 μM. The intrinsic peroxidase-like activity of BNNS@CuS followed the typical Michaelis–Menten kinetics. The method was further utilized for the visual detection of total cholesterol in human serum and showed high selectivity toward cholesterol. Our research manifested that the cholesterol biosensing method based on BNNS@CuS was cost-effective, reliable, highly efficient and feasible. [ABSTRACT FROM AUTHOR]