Boron Nitride Research Articles

An Innovative Concept of Membrane-Free Redox Flow Batteries with Near-Zero Contact Distance Between Electrodes.

Given that the ion-exchange membrane takes up more than 30% of redox flow battery (RFB) cost, considerable cost reduction is anticipated with the membrane-free design. However, eliminating the membrane/separator would expose the membrane-free RFBs to a higher risk of short-circuits, and the dendrite growth may aggravate this issue. The current strategy based on expanding distances between electrodes is proposed to address short-circuit issues. Nevertheless, this approach would decrease the energy efficiency (EE) and could not restrain dendrite growth fundamentally. Herein, an inexpensive and electron-insulating boron nitride nanosheets (BNNSs)-Nylon hybrid interlayer (BN/Nylon) is developed for general membrane-free RFBs to achieve "near-zero distance" contact between electrodes. And the Lewis acid sites (B atoms) in BNNS can interact with the Lewis base anions in electrolytes, enabling a reduced Pb2+concentration gradient. Additionally, the ultrahigh thermal conductivity and mechanical strength of BNNSs promote the uniform plating/stripping process of Pb and PbO2. Compared with conventional soluble lead RFBs, introducing BN/Nylon interlayers boosts EE by ≈38.2% at 25mAcm-2, and extends the cycle life to 100 cycles. This innovative strategy premieres the application of the BN/Nylon interlayer concept, offering a novel perspective for the development of general membrane-free RFBs.

Alternative inner filling and outer surface coating of BNNT by Tungsten(VI) oxide for supercapacitor electrode

The motivation behind this research is to address the need for advanced energy storage materials by exploring the selective filling and coating of boron nitride nanotube (BNNT) with tungsten(VI) oxide (WO3) to enhance the pseudocapacitive performance. In this study, we present a novel synthesis method that allows precise control over the extent of filling and coating, aiming to create tailored hybrid structures. Morphological and structural analysis confirm the filling and coating of BNNT by WO3. Inner filling and outer surface coating of BNNT by WO3 significantly impact on the electrochemical properties. The filling of WO3 within the BNNT can enhance the stability of the system, whereas outer surface coating of BNNT by WO3 improves the capacitive performances. The role of BNNT influences both these phenomena by acting as electrolyte transportation channel as well as stabilizing the WO3. In three electrode study, WO3 coated BNNT showed the maximum specific capacitance of 856 F/g at 1 A/g. An asymmetric supercapacitor device using WO3 coated BNNT as positive electrode revealed the maximum specific capacitance of 137 F/g at 2 A/g current density with an improved energy density of 52 W h/kg. The WO3 coated BNNT-based asymmetric supercapacitor device also showed ∼81 % specific capacitance retention after the completion of 10,000 GCD cycles, whereas WO3 filled BNNT-based supercapacitor device demonstrated better stability (∼94 % specific capacitance retention) due to the filling and stabilization of pseudocapacitive WO3 by BNNT.

Prediction of phonon properties of cubic boron nitride with vacancy defects and isotopic disorders by using a neural network potential

Cubic boron nitride (c-BN) is a promising ultra-wide bandgap semiconductor for high-power electronic devices. Its thermal conductivity can be substantially modified by controlling the isotope abundance and by the quality of a single crystal. Consequently, an understanding of the phonon transport in c-BN crystals, with both vacancy defects and isotopic disorders at near-ambient temperatures, is of practical importance. In the present study, a neural network potential (NNP) for c-BN has been developed, which has facilitated the investigation of phonon properties under these circumstances. As a result, the phonon dispersion and the three- and four-phonon scattering rates that were predicted with this NNP were in close agreement with those obtained from density-functional theory (DFT) calculations. The thermal conductivities of the c-BN crystals were also investigated, with boron (B) vacancies ranging from 0.0% to 0.6%, by using equilibrium molecular dynamics simulations based on the Green-Kubo formula. These simulations accurately capture vacancy-induced phonon softening, localized vibration modes, and phonon localization effects. As has previously been experimentally prepared, four isotope-modified c-BN samples were selected for analyses in the evaluation of the impact of isotopic disorders. The calculated thermal conductivities aligned well with the DFT benchmarks. In addition, the present study was extended to include a c-BN crystal with a natural abundance of B atoms, which also contained B vacancies. Reasonable thermal conductivities and vibrational characteristics, within the temperature range of 250–500 K, were then obtained.

Experimental and Theoretical Insights into Interfacial Properties of 2D Materials for Selective Water Transport Membranes: A Critical Review.

Interfacial properties, such as wettability and friction, play critical roles in nanofluidics and desalination. Understanding the interfacial properties of two-dimensional (2D) materials is crucial in these applications due to the close interaction between liquids and the solid surface. The most important interfacial properties of a solid surface include the water contact angle, which quantifies the extent of interactions between the surface and water, and the water slip length, which determines how much faster water can flow on the surface beyond the predictions of continuum fluid mechanics. This Review seeks to elucidate the mechanism that governs the interfacial properties of diverse 2D materials, including transition metal dichalcogenides (e.g., MoS2), graphene, and hexagonal boron nitride (hBN). Our work consolidates existing experimental and computational insights into 2D material synthesis and modeling and explores their interfacial properties for desalination. We investigated the capabilities of density functional theory and molecular dynamics simulations in analyzing the interfacial properties of 2D materials. Specifically, we highlight how MD simulations have revolutionized our understanding of these properties, paving the way for their effective application in desalination. This Review of the synthesis and interfacial properties of 2D materials unlocks opportunities for further advancement and optimization in desalination.

Mechanical, thermal, and electrical properties of 2D nanomaterials for advanced applications

The rapid development of two-dimensional (2D) Nanomaterials, primarily graphene-based nanoplates or nanosheets, hexagonal boron nitride (hBN), dichalcogenides of transition metals (TMDs), MXenes, metal-/covalent- organic frameworks, (MOFs/COFs) over the last decade has been driven by the great success of graphene. Despite their high similarity in lattice structure, the uniqueness of their specific atomic arrangement gives rise to phenomenal properties such as electrical, mechanical, and thermal, and thus finds a broad array of applications in electronics, optoelectronics, energy storage devices, solar cells, composites, manufacturing, and so on. This paper majorly focuses on the various properties of 2D Nanomaterials including electrical, mechanical, and thermal properties. Due to the promising properties of 2D Nanomaterials, various applications of 2D Nanomaterials are highlighted. The future outlook of 2D Nanomaterials has also been discussed.

Solution-phase sample-averaged single-particle spectroscopy of quantum emitters with femtosecond resolution.

The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. Systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. Here we utilize a combination of fluorescence correlation spectroscopy and ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity. We employ this approach to study heterogeneous emitters in two-dimensional hexagonal boron nitride. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron-phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Corroborated with theory, this translates to the photon fidelity characterization of cascaded emission efficiency and decoherence time. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.

High Quasi-Isotropic Thermal Conductivity of Polydimethylsiloxane Nanocomposites with Hexagonal-Boron Nitride Microspheres and Flakes

High Quasi-Isotropic Thermal Conductivity of Polydimethylsiloxane Nanocomposites with Hexagonal-Boron Nitride Microspheres and Flakes

Boron nitride nanosheets enhanced the thermo-optical properties of cotton fabric for energy saving and personal heat management

Boron nitride nanosheets enhanced the thermo-optical properties of cotton fabric for energy saving and personal heat management

Environmentally Friendly High‐Performance Polydimethylsiloxane Composites Reinforced with Renewable Cellulose Nanocrystals Based on Dynamic Silyl Ether Linkages

AbstractEnvironmentally friendly high‐performance composites made from either reprocessable polymer matrix or renewable fillers have become increasingly significant in order to reach a sustainable future. Herein, polydimethylsiloxane/modified cellulose nanocrystals (PDMS/mCNC) composites showing outstanding mechanical and reprocessable properties via silyl ether linkages are prepared. With only 1 wt% mCNC, the PDMS/mCNC composite exhibits the tensile strength of 2.96 MPa, which is twice that of the pure PDMS elastomer, while the toughness can achieve 7.32 MJ m−3. Remarkably, the reprocessing efficiency can be as high as 100% even for triple reprocessing process. Additionally, the favorable effect of mCNC on constructing hybrid filler network within vitrimers is explored for the first time. Selection of boron nitride nanosheet (BNNS) as the functional filler, 40 wt% BNNS is uniformly dispersed by only a small amount of mCNC and a homogeneous thermally conductive network is built, with the thermal conductivity of the PDMS/mCNC@BNNS composite increasing remarkably to 2.901 W m−1 K−1. In a word, this work paves the way to develop sustainable, mechanically strong, and reprocessable composites with mCNC as a renewable bio‐filler.

Predicting Quantum-Mechanical Partial Charges in Arbitrarily Long Boron Nitride Nanotubes to Accurately Simulate Nanoscale Water Transport.

Single-walled boron nitride nanotubes (BNNTs) have been explored for various applications, ranging from water desalination to osmotic power harvesting. However, no simulation work so far has modeled the changes in the partial charge distribution when a flat sheet is rolled into a tube, hindering the ability to perform accurate molecular dynamics (MD) simulations of water flow through BNNTs. To address this knowledge gap, we employ electronic density functional theory (DFT) calculations to precisely estimate quantum-mechanically derived partial charges on boron (B) and nitrogen (N) atoms in BNNTs of varying lengths and diameters. We observe a spatially varying charge distribution inside both armchair and zigzag nanotubes of finite lengths. Performing DFT calculations for longer BNNTs is computationally intractable, even with state-of-the-art computing resources. To solve this issue, we devise a charge assignment scheme to predict partial charges for longer BNNTs using DFT data for shorter nanotubes, thus overcoming the need to perform more expensive DFT calculations. We show that these charges reproduce the electrostatic potential predicted from first-principles simulations. Subsequently, we carried out MD simulations to predict the effect of the charge distribution inside BNNTs on water flow enhancement via them. We find that using uniform charges leads to an underprediction in flow enhancement, as compared to using quantum-mechanical charges for both armchair and zigzag BNNTs. We also incorporate atomic vibrations into our simulations and show that these vibrations lead to a reduction in the water flow through aperiodic BNNTs. Our work demonstrates the requirement of a quantum-mechanical charge assignment scheme for BNNTs and evolves a framework to assign charges to nanotubes of arbitrary length, thus allowing realistic MD simulations of long BNNTs using accurate partial charges.

Stacking effects on dynamic mechanical behavior of bilayer hexagonal boron nitride under impact

Hexagonal boron nitride (h-BN) is a promising material for ballistic armor due to its excellent mechanical properties, enriched by different bilayer stacking arrangements. Molecular dynamics methods are used to study the stacking effects on the static and dynamic mechanical properties of bilayer h-BN. The AB (nitrogen) stacked bilayer structure attracts our attention because of its superior interlayer synergistic ability to resist projectile indentation up to a maximum force of 152.89 nN, which is about 22.9 % higher than the average value of other stacked bilayers. The impact response of bilayer h-BN with AB (nitrogen) stacking arrangement is then investigated at velocities of 2–4 km/s, which has the highest critical perforation velocity of 3.075 km/s, increased by 36.7 % compared to monolayer h-BN. At a low impact velocity of 2.5 km/s, the AB (nitrogen) stacked h-BN bilayer spends the shortest time to dissipate the impact energy of projectile and remains intact, while the top layers of other stacked bilayers are penetrated. At high impact velocities, a perforation event occurs, accompanied by multiple deflections of crack tips from zigzag to armchair to zigzag again, which intrinsically enhances the toughness of material. This study provides more understanding of the dynamic mechanical behavior of bilayer h-BN, as well as the design of armor structures based on stacking arrangements of 2D materials.

Highly conductive carbon nanotubes-boron nitride-thermoplastic polyurethane composite thin films with ultra broadband and efficient electromagnetic interference shielding up to 110 GHz and heat dissipation abilities

The miniaturization and integration of electronic devices have led to an increased accumulation of heat, which can disrupt normal functioning. Their functionalities are also severely affected when they are exposed to the abundant electromagnetic interference (EMI) resulting from the rapid development of fifth-generation telecommunication technology extended to mmWaves and sixth-generation telecommunication frequencies up to 110 GHz. Therefore, it is urgent to develop composite materials with excellent EMI shielding effectiveness and heat dissipation abilities. Herein, we have fabricated an all-in-one thin film composite using carbon nanotubes (CNT), boron nitride (BN), and thermoplastic polyurethane (TPU) through a layer-by-layer casting method to create a composite supported by hydrogen bonding with impressive EMI shielding and heat dissipation properties. The high electrical conductivity of the CNT-BN-TPU composite resulted in the highest EMI shielding effectiveness, ranging from 90.66 dB in Ka-band to 79.8 dB in W-band, at a thickness of 100 μm, with absorption efficiency of 83.07 % at 34 GHz and 80.85 % at 100 GHz, respectively. The composite demonstrated excellent heat dissipation, thanks to its outstanding out-of-plane thermal conductivity, which reached 1.971 W/mK. We believe that our proposed method for producing an all-in-one composite thin film with excellent EMI shielding and thermal management capabilities could be a useful approach for the next generation of smart electronic devices.

A Study of Water-Based Nanolubricants Using Hexagonal Boron Nitride (hBN)-Based Nanocomposites as Lubricant Additives

An Rtec ball-on-disk tribometer was used to investigate the tribological performance of the synthesised water-based nanolubricants containing hBN/TiO2 nanocomposite at room temperature. The water-based nanolubricants with different concentrations were prepared by adding glycerol and sodium dodecyl benzene sulfonate (SDBS) under ultrasonication. These as-prepared nanolubricants demonstrated exceptional dispersion stability for 7 days without distinct sedimentation. The results indicate that the water-based nanolubricants with an overall concentration of 1.0 wt% at different ratios (hBN: TiO2 = (1:0), (0.7:0.3), (0.5:0.5), (0.3:0.7), (0:1)) can effectively reduce the coefficient of friction (COF) and the wear of the ball and disk. In particular, the water-based nanolubricant containing 0.5 wt% hBN and 0.5 wt% TiO2 exhibited the best tribological performance, leading to a significant reduction in COF up to 70%, and decreased the wear area of the ball and disk by up to 79.57% and 60.40%, respectively, compared to those obtained using distilled water. The lubrication mechanisms were mainly attributed to the formation of a protective film, and the mending, polishing, rolling, and synergistic effects of the hBN nanosheets and TiO2 nanoparticles.

A multifunctional integrated coating reinforced with exfoliated boron nitride towards superior decorative, antibacterial, durable, and flame-retardant performances

To solve the problems of traditional transparent fireproof coatings with a single-function nature and susceptibility to environmental aging, a novel functionalized exfoliated boron nitride (h-BN) with organophosphate (PPB) was synthesized and applied in an amino resin, preparing an integrated coating with decorative, fire-resistant, antibacterial, and weathering functions. The results indicate that the introduction of h-BN not only maintains the coating's high transparency but also enhances its hardness and adhesion capabilities. Furthermore, the presence of h-BN positively influences the flame retardance and smoke suppression of MBPPB coatings. Notably, when the mass ratio of PPB to h-BN is 98:2, the resulting MBPPB4 coating reduces the flame spread rate (FSR) by 45.7% and the smoke density rating by 62.6% compared to MBPPB0 coating without h-BN. Thermogravimetric analyses indicate that coatings containing h-BN exhibit superior char formation and thermal stability, where the MBPPB3 coating, with a PPB to h-BN ratio of 98.5:1.5, shows a 49.8% higher char yield at 800 °C than MBPPB0. The accelerated aging test demonstrates that the incorporation of h-BN also reduces the incidence of coatings blistering and cracking, thereby exhibiting outstanding weatherability. Additionally, h-BN significantly enhances the coating's antibacterial efficacy, with an E. coli inhibition rate of up to 99.0% for MBPPB3 coating.

Unveiling the cobalt vanadate supported hexagonal boron nitride nanocomposite for photocatalytic wastewater treatment: Enhanced degradation of dyes, antibiotics, and real industrial wastewater

In recent years, the expansion of industrial sectors has imposed a burden on water resources globally owing to unsustainable consumption and discharges into the environment. Here, a Co3V2O8 (CV)/hexagonal boron nitride (HBN) heterojunction has been constructed using an applicable solid-state technique that produces efficient photocatalytic action during water cleanup activities. The nanocomposite was studied utilizing different approaches such as XRD, SEM, TEM, FT-IR, EDX, XPS, UV–Vis spectroscopy, EIS, PL, BET, and M − S plots. The pristine HBN has a band gap of 5 eV, while the CV/HBN nanocomposite has a band gap of 1.8 eV. According to our findings, the photocatalyst has a high degradation ratio of up to 98.1%, 89.8%, 87.5%, 96.5%, and 90.2% in brilliant cresyl blue (CB), rhodamine-B (Rh–B), amoxicillin (AMX), metronidazole (MNZ), and industrial wastewater (IW) under visible light irradiation, correspondingly. It emphasizes that the remarkable photocatalytic activity is mostly due to the photocatalyst's superior performance and dominant absorption of visible light, as well as the efficient photogenerated carrier separation brought about by the interaction of cobalt vanadate and HBN. The catalyst demonstrated stable behavior, adhering to five reuse cycles. The present research reveals that the CV/HBN nanocomposite is a very stable and active photocatalyst that may be used as an alternative to costlier noble metal-based photocatalysts in photocatalysis applications. When compared to untreated IW, the degraded IW sample exhibits superior plant growth, which is visible from the phytotoxicity tests.

Enhancement of Flexural Strength by Slip Casting Cordierite Ceramics with h-BN Nanoparticles

In this study, we enhanced the flexural strength of cordierite ceramics by incorporating h-BN (hexagonal boron nitride) nanoparticles, facilitated by the slip casting process. Initially, commercial cordierite powder with an average particle size of 10 mm underwent a ball-milling process to reduce the size to 2.5 mm and simultaneously achieve a narrower particle size distribution. The resulting slurry, composed of 67% solid content, exhibited improved stability during the slip casting process for both pristine cordierite and the mixture containing 1 – 2 wt% h-BN nanoparticles. After sintering, the bulk material containing 2wt% h-BN nanoparticles demonstrated a remarkable flexural strength of 174.8 MPa, a significant improvement compared to the initial 119.5 MPa obtained without the addition of h-BN. It is worth noting that the introduction of h-BN nanoparticles did not induce substantial changes in dielectric constant and thermal conductivity, indicating that the desired mechanical enhancement did not compromise other crucial material properties. This research demonstrates a successful approach to concurrently optimize the flexural strength, dielectric constants, and thermal conductivity of cordierite ceramics. This breakthrough opens up new avenues for advanced applications in a wide range of fields, from electronics to aerospace, where high-strength, thermally stable materials are in demand.

First-principle study of CrO2-BNNT-CrO2 based MTJ device using EHTB model and its application in a MRAM circuit

In this work we investigated the performance of Single-Walled Boron Nitride Nanotube (SWBNNT) sandwiched between CrO2 based Magnetic Tunnel Junction (MTJ) structures with atomistic simulations. MTJ based device-level simulation was performed using the Extended Huckel based Tight Binding (EHTB) model. The SWBNNT as a dielectric layer and CrO2 as Ferromagnetic (FM) layers based Magnetic Tunnel Junction (MTJ) heterostructure was computed. The proposed MTJ device operates at the nano-Ampere (nA) range depicting its potential application in a low-powered nanoelectronics device. It also shows a promising Tunnel Magnetoresistance (TMR) effect. The practical circuit-level implementation of the proposed MTJ device in Magnetic Random-Access Memory (MRAM) was validated using LTspice. Hence, the calculated static power consumption and writing energy per bit was minimal for S1 and S2 based MRAM circuit. The perfect switching operation was depicted by the proposed MTJ device based MRAM.

Ab initio study of the vibrational spectra of amorphous boron nitride

Boron Nitride (BN) is an interesting polymorphic insulator that is commonly found in four different crystalline structures, each one with different electrical and mechanical properties which makes it an attractive material for technological and industrial applications. Seeking to improve its features, several experimental and simulational works have studied the amorphous phase (a-BN) focusing on electronic and structural properties, pressure-induced phase transformations, and a hydrogenated form of a-BN. By means of ab initio Molecular Dynamics and our well-proven amorphization process known as the undermelt-quench approach, herein three amorphous supercells were computationally generated, two with 216 atoms (densities of 2.04 and 2.80 g cm−3) and a third one with 254 atoms (density of 3.48 g cm−3). The topology, the vibrational density of states and some thermodynamic properties of the three samples are reported and compared with existing experiments and with other computational results.

Tribological Behaviors and the Lubrication Mechanism of Functionalized Boron Nitride Nanosheet-Containing Fluid for Titanium Alloy Cold Rolling

Tribological Behaviors and the Lubrication Mechanism of Functionalized Boron Nitride Nanosheet-Containing Fluid for Titanium Alloy Cold Rolling

Facile preparation of thermally conductive fiber film by self‐assembling interconnected boron nitride nanosheets for effective thermal interface materials

AbstractBoron nitride (BN) has garnered significant attention for its potential in developing thermally conductive materials owing to its inherent insulating properties and high thermal conductivity. However, achieving high thermal conductivity in bulk materials or 3D structures constructed by BN sheets has remained challenging. In this study, we present a novel approach to design a high‐quality BN fiber using xanthan gum (XG) as a skeleton, aiming to facilitate heat dissipation in integrated circuits. The resulting thermally conductive film, with orderly and compactly arranged BN sheets in the XG skeleton, exhibits a remarkable in‐plane thermal conductivity of 8.26 Wm−1 K−1 and an out‐of‐plane thermal conductivity of 1.35 Wm−1 K−1. This film efficiently enables fast heat dissipation for LED chips and thermoelectric generators. Finite element simulation further supports the efficient heat transfer capacity of the BN fiber films.Highlights A high‐quality BN fiber was prepared by a facile approach. The BN fiber film exhibited high thermal conductivity. This film enables fast heat dissipation in practical applications.