Boron Nitride Research Articles

Unlocking the Trade-off Between Intrinsic and Interfacial Thermal Transport of Boron Nitride Nanosheets by Surface Functionalization for Advanced Thermal Interface Materials.

The increasing computing power of AI presents a major challenge for high-power chip solution and heat dissipation. Boron nitride nanosheet-based thermal interface materials (BNNS-based TIMs) exhibit excellent electrical insulation property, ensuring the secure and stable operation of chips. However, the efficiency of micro/nano interfacial thermal transport is limited, impeding further enhancements in the thermal conductivity (TC) of BNNS-based TIMs. Here, a strategy of surface functionalization is reported to unlock the trade-off between the intrinsic and interfacial thermal transport of BNNS within TIMs. These results suggest that the surface functionalization maintains the intrinsic high TC of BNNS while significantly increasing binding energy between micro/nano interfaces in BNNS-based TIMs, effectively reducing interfacial thermal resistance of BNNS joint interfaces and interfaces between BNNSs and the matrix by 50% and 26.1%, respectively. The BNNS-based TIMs exhibit excellent TC (≈21-25W/(m·K)) and ultralow Young's modulus, which can promote the development of flexible high-performance chip cooling technology in the AI industry.

Revealing polytypism in 2D boron nitride with UV photoluminescence

AbstractBoron nitride exhibits various crystal structures. The subgroup of layered boron nitrides includes several polytypes such as hexagonal (hBN), Bernal (bBN), and rhombohedral (rBN) BN. The latter two are non-centrosymmetric, potentially leading to piezoelectric or ferroelectric properties. A key challenge related to the polytypism of sp2-bonded BN is distinguishing between these polytypes. We demonstrate that the optical response of the 4.1-eV defect can be used to differentiate hBN from rBN. Photoluminescence and cathodoluminescence measurements on samples grown by metalorganic vapor phase epitaxy (MOVPE) show a zero-phonon line at 4.096 eV for hBN and 4.143 eV for rBN. Our calculations confirm that the photoluminescence originates from a carbon dimer, CBCN (C2), which is sensitive to the local environments of different polytypes. We demonstrate that different polytypic compositions of hBN and rBN can be achieved by MOVPE, which could pave the way for future applications in large-area van der Waals heterostructures.

Adsorption of magnesium porphyrin on Au(111)-supported graphene and hexagonal boron nitride monolayers: A first-principles study

Adsorption of magnesium porphyrin on Au(111)-supported graphene and hexagonal boron nitride monolayers: A first-principles study

Synthesis, characterisations and applications of boron nitride based hybrid metal matrix composites

ABSTRACT This study focuses on how reinforcements impact the base material (specifically AA 6082) regarding its microstructure, mechanical behaviour& corrosion behaviour. Boron nitride (BN) & molybdenum disulphide (MoS2) employed as reinforcing materials ranged from 1% to 3% of BN & 1% to Constant MoS2. The composite materials were produced utilising the stir casting technique. X-ray diffraction (XRD), scanning electron microscope (SEM) with Energy Dispersive spectroscopy (EDAX) & an optical microscope (OM) were used to examine microstructural phase identification analysis. Tensile, compressive, impact, density& porosity fracture mechanisms were investigated by mechanical testing. BN & MoS2 reinforced particles’ presence in the samples is confirmed by XRD and microstructural pictures showing consistent matrix reinforcement distribution. According to the findings, incorporating BN & MoS2 reinforcements improved the mechanical & corrosion properties but slightly reduced the impact strength. The fractured samples revealed micro cuts, micro ploughing, cracks, trans-granular cleavage facets, dimples in the tensile & impact tests. Reduction in Corrosion rate was achieved gradually by adding reinforcement particles for the composites.AA6082, 3 wt: % BN, & 1 wt.% MoS2 composites have shown a decrease in corrosion current density by 1.901 mA/cm2 & an increase in charge transfer resistance by 99.934 Ω cm-2, attributed to passivation.

Biological evaluation of ZrO2 composites modified with different ceramics additives

In this work, zirconia (ZrO2) composites modified with bioactive hydroxyapatite (HAp), hexagonal boron nitride (hBN), bioglass (BG), and bioglass with copper (BGCu) via the hydrothermal method were synthesized. The aim was to obtain highly bioactive and cytocompatible materials that could combine beneficial properties of inert and bioactive ceramics. Such materials could be applied as fillers for tooth extraction cavities, guaranteeing osseintegration without the need to introduce additional bone cements or other adhesives. It was proven that while all materials were favourable towards cells adhesion and growth, the HAp and BG-doped ones facilitated early adhesion, especially when compared to unmodified ZrO2. Only the HAp-doped materials showed satisfactory bioactivity results, with a well-developed apatite layer forming on their surfaces. This study confirms that the Hap-doped ZrO2 is suitable for treating bone defects.

Dry sliding wear behaviour of AA6082/BN/Mos2 hybrid metal matrix composites synthesized using stir casting process

This study examines the wear behaviour of AA6082/x Boron Nitride (BN) (x = 1, 2, 3 wt.%)/1 wt.% of Molybdenum Disulphide (MoS2), a novel hybrid metal matrix composite (MMC), under dry sliding conditions. The composite was fabricated through liquid-state processing, i.e., stir casting. A pin-on-disk tribometer was used to estimate the coefficient of friction (COF) and wear rate by varying tribological process parameters under dry sliding conditions. The results show that at the maximum load of 40 N, the wear rate of the unreinforced alloy is observed 4.077 × 10−2 mm3/m, while at the AA6082/3 wt. of %, BN/1 wt. % of the MoS2 composite's wear rate is reduced to 2.162 × 10−2 mm3/m. Further, the wear rate increases as the sliding distance increases from 500 m to 2000 m. Moreover, the friction coefficient of the unreinforced alloy is observed 0.37, whereas the AA6082/3 wt.% of BN/1 wt.% of MoS2 composites is observed 0.31 under reduced loads. It might be due to the presence of hard ceramic BN and MoS2 reinforcements enhancing the developed composite's resistance to wear by forming a mechanically mixed layer (Fe2O3) on the sliding contact surface. Moreover, the novel hybrid composite materials exhibit a lower coefficient of friction at higher sliding velocities, sliding distances, and applied loads. However, minimal fine grooves with limited abrasion are observed on the worn surface, which was examined through a scanning electron microscope.

Performance of sandwich type fire-resistant flexible composite phase change material PEE@EBF for battery thermal management and runaway protection

To mitigate the risks of overheating and thermal runaway in lithium-ion batteries, this study proposes a novel sandwich-type fire-resistant flexible composite phase change material (CPCM), referred to as PEE@EBF. The core material (PEE) was created by melt-blending paraffin wax (PW), expanded graphite (EG), and ethylene–vinyl acetate copolymer (EVA). The outer layer, a fire-resistant coating (EBF), was applied to the surface of PEE and consists of epoxy resin (EP), boron nitride (BN), and the composite flame retardant (CFR). Test results demonstrated that PEE@EBF maintained structural integrity, exhibiting no significant deformation or leakage after being heated at 80 °C for 5 h. PEE@EBF also displayed a high latent heat of 166.6 J/g, thermal conductivity of 0.8 W/(m∙K), and excellent electrical insulation properties. Furthermore, it achieved a UL94 V-0 flame retardant rating, with notable reductions in peak heat release rate (PHRR) and peak smoke production rate (PSPR) by 67.8 % and 81.8 %, respectively. During long-term cycling at 4C, the peak temperature (PT) and maximum temperature difference (MTD) of batteries in the module incorporating PEE@EBF were reduced by 11.8 °C and 4 °C, respectively, compared to natural convection cooling. In addition, the heat generated during the battery thermal runaway was efficiently absorbed and transferred by PEE@EBF, delaying the irreversible thermal runaway process by 633 s. This indicated that the sandwich-type PEE@EBF was suitable for thermal management and fire protection in lithium-ion batteries or energy storage devices.

H-BN-assisted-transferred metal contacts to InSe for twodimensional multifunctional electronic devices

Abstract Metal contacts to two-dimensional semiconductors play a crucial role in determining the electrical performance of the electronic devices. However, traditional three-dimensional metal deposition processes will bring damage to two-dimensional semiconductors and cause significant Fermi-level-pinning effects. In this work, we report a hexagonal boron nitride (h-BN)-assisted-transferred method for metal contacts to few-layered InSe for construction of two-dimensional functional electronic devices. Using transferred Pt electrodes as the contact, p-type dominated ambipolar conduction behavior with the hole Schottky barrier height (SBH) approaching 0 meV was observed in field-effect transistors (FETs) based on multilayered InSe. Based on this, using a dual-gate modulating method, multiple types of InSe homojunctions, including p-p, n-n, p-n and n-p junctions, could be constructed. For InSe p-n homojunctions, a current rectification ratio of over 104 and optoelectronic detection capabilities were achieved. Furthermore, a complementary metal-oxide-semiconductor (CMOS) inverter with an ultra-high voltage gain exceeding 60 at VDD = -1 V was constructed. Our h-BN-assistedtransferred metal contact method can be easily extended to other two-dimensional semiconductors for the construction of complementary electronic and optoelectronic devices.

Recyclable and highly thermally conductive nanocomposite with binary thermally conductive networks constructed from boron nitride nanoribbons and nanosheets

Technological advances have accelerated the development of high-performance insulation-based Thermal Interface Materials (TIMs), leading to increased generation of electronic waste. A significant challenge is the development of recyclable TIMs with superior thermal conductivity. Hemiaminal dynamic covalent network (HDCN) polymers are considered as an ideal matrix material for recyclable TIMs due to their high degradability at low pH (pH < 2). In this work, binary thermally conductive paths of hexagonal boron nitride nanoribbons (BNNRs) and boron nitride nanosheets (BNNSs) are introduced into the HDCN to improve the thermal conductivity of HDCN without sacrificing its electrically insulating properties. The functional BNNSs (f-BNNSs) are attached onto the surfaces of BNNRs to achieve the homogeneous distribution of nanosheets within the HDCN. Benefiting from the binary thermally conductive paths, an excellent in-plane thermal conductivity of 3.12 W m−1K−1 for BNNS-BNNR/HDCN nanocomposite is achieved at a BN loading of 14 wt% (containing 2 wt% BNNRs and 12 wt% f-BNNS), increased by 1299 % comparing to the pure HDCN polymer, as well as superior to those reported for polymer composites with similar loading of BNNRs or BNNSs. Additionally, the nanocomposite demonstrated efficient recyclability of BNNSs and BNNRs hybrid fillers in an acidic environment (pH < 2) at 25 °C with a recycling efficiency of 82 %. Notably, the nanocomposite exhibited noteworthy electrical insulation properties. This study demonstrates the potential of BNNS-BNNR/HDCN as a recyclable TIMs and provides a new idea for the future research and development of recyclable high performance TIMs.

Surface defect detection model of laser cutting polycrystalline cubic boron nitride tool based on asymptotic fusion strategy

Due to the polycrystalline cubic boron nitride tool has the characteristics of high hardness, brittleness, etc., it is easy to break the tool or produce defects in the laser cutting process, which affects the cutting performance of the tool. Traditional defect detection methods can no longer meet the needs of modern manufacturing. Aiming at the problems of low accuracy and poor real-time detection of surface defects on laser-cutting polycrystalline cubic boron nitride tools, this study proposes the surface defect detection model of laser cutting polycrystalline cubic boron nitride tool based on asymptotic fusion strategy, which fills the gap in the field. In the backbone network, the C3SE module is constructed by modeling the correlation between feature channels to improve the model’s focus on key features in order to enhance the feature extraction and processing capability of the backbone network; In the neck network, adaptive spatial fusion operation and direct interaction of non-adjacent layers are utilized for multi-scale information fusion, and the asymptotic feature pyramid network for object detection (AFPN) is used instead of the FPN structure to improve the detection performance; In the head network, a soft suppression mechanism is introduced to reduce the overlapping frame score using a decay function, thus improving the detection accuracy. The experimental results based on the self-constructed laser-cutting polycrystalline cubic boron nitride tool surface defects dataset show that the average accuracy of the AFFS-YOLO model is improved by 5.6% compared with that of the YOLOv5 model, reaching 86.1%, and the detection effect is better than that of the original network and other classical target detection networks.

Probing the limits for coherent optical control of a mechanically decoupled defect center in hexagonal boron nitride

The coherent control of a two-level system is among the most essential challenges in modern quantum optics. Understanding its fundamental limitations is crucial, also for the realization of next generation quantum devices. The quantum coherence of a two-level system is fragile in particular, when the two levels are connected via an optical transition, which, at the same time, enables the manipulation of the system. When such quantum emitters are located in solids the coherence suffers from the interaction of the optical transition with the solid state environment, which requires the sample to be cooled to temperatures of a few Kelvin or below. Here, we use a mechanically isolated quantum emitter in hexagonal boron nitride to explore the individual mechanisms which affect the coherence of an optical transition under resonant drive. We operate the system at the threshold where the mechanical isolation collapses in order to study the onset and temperature-dependence of dephasing and independently of spectral diffusion. The insights on the underlying physical decoherence mechanisms reveal a limit in temperature until which coherent driving of the system is possible. This study enables to increase the operation temperature of hBN-based quantum devices, therefore reducing the need for cryogenic cooling.

Cold‐Sprayed Boron‐Nitride‐Nanotube‐Reinforced Aluminum Matrix Composites with Improved Wear Resistance and Radiation Shielding

In this study, the influence of cold‐spray processing on the integration of 1D boron nitride nanotubes (BNNTs) into aluminum (Al) matrix composite deposits is delved into. Successful deposition of Al‐BNNT composite is achieved by pre‐spray dispersion of BNNTs in Al powder via wet mixing aided by ultrasonication. Pure Al powder deposition at 380 °C is limited by nozzle clogging, restricting the deposit thickness to 0.2 mm, while the presence of BNNTs enables longer spraying due to nozzle cleaning and damping by hard BNNTs, allowing thicker Al‐BNNT deposits of about 2 mm. Microstructural analysis reveals severely deformed Al splats decorated with a uniformly distributed network of BNNTs at the intersplat boundaries, reducing the porosity from 8% to 4% and increasing the splat flattening by 40%. Tribological testing demonstrates resistance of BNNTs to normal force, resulting in a 21% improvement in coefficient of friction and a 65% reduction in wear volume in the Al‐BNNT composite. Additionally, incorporating 3 vol.% BNNTs enhances the neutron radiation shielding by 35%. These improvements in the composites are attributed to reduced porosity and the inherent properties of BNNTs, such as high strength, the ability to produce tribofilm lubrication during dry sliding wear, and their high neutron absorption cross‐sectional area.

Ultraflat Cu(111) foils by surface acoustic wave-assisted annealing

Ultraflat metal foils are essential for semiconductor nanoelectronics applications and nanomaterial epitaxial growth. Numerous efforts have been devoted to metal surface engineering studies in the past decades. However, various challenges persist, including size limitations, polishing non-uniformities, and undesired contaminants. Thus, further exploration of advanced metal surface treatment techniques is essential. Here, we report a physical strategy that utilizes surface acoustic wave assisted annealing to flatten metal foils by eliminating the surface steps, eventually transforming commercial rough metal foils into ultraflat substrates. Large-area, high-quality, smooth 2D materials, including graphene and hexagonal boron nitride (hBN), were successfully grown on the resulting flat metal substrates. Further investigation into the oxidation of 2D-material-coated metal foils, both rough and flat, revealed that the hBN-coated flat metal foil exhibits enhanced anti-corrosion properties. Molecular dynamics simulations and density functional theory validate our experimental observations.

Transferrable GaN-based Micro-LED heterostructures grown on h-BN for optogenetic applications

Individually transferrable GaN-based MQWs micro-LED structures grown on two-dimensional (2D) hexagonal boron nitride (h-BN) have been demonstrated. Different sizes (60 × 30 µm, 60 × 60 µm, 90 × 60 µm and 90 × 90 µm) of GaN-based LED heterostructures on layered h-BN were grown on dielectric SiN patterned sapphire substrates using Metal Organic Vapor Phase Epitaxy (MOVPE). Scanning electron microscope (SEM) images show micro-LEDs were grown with high selectivity within the mask opening areas. Consistent MQWs emission from micro-LEDs was observed at 452 ± 2 nm by cathodoluminescence (CL) spectroscopy for all micro-LED sizes. The structural and optical quality were similar to the GaN-based-LEDs grown on unpatterned substrates. In addition, we have successfully demonstrated the lift-off and transfer of individual micro-LEDs to arbitrary flexible templates using a transfer printing machine, which can be addressed by full front-end process. These studies highlight the role of combination of van der Waals (vdW) epitaxy and selective area growth (SAG) in facilitating the direct realization of dimensionally defined III-Nitride micro-LED structures and the mechanical release and transfer of these micro-LEDs to templates suitable for flexible display and optogenetics applications.

Fundamental optical transitions in hexagonal boron nitride epilayers

Fundamental optical transitions in hexagonal boron nitride (h-BN) epilayers grown on sapphire by metal–organic chemical vapor deposition (MOCVD) using triethylboron as the boron precursor have been probed by photoluminescence (PL) emission spectroscopy. The low temperature (10 K) PL spectrum exhibits two groups of emission lines. The first group includes the direct observation of the free exciton and impurity bound exciton (BX) transitions and phonon replicas of the BX transition, whereas the second group is attributed to the direct observation of the band-to-band transition and its associated phonon replicas. The observations of zero-phonon lines of the band-to-band and exciton transitions, which are supposedly forbidden or “dark” in perfect h-BN crystals, result from a relaxed requirement of momentum conservation due to symmetry-breaking in the presence of high concentrations of impurities/defects and strain, which in turn provided more deterministic values of the energy bandgap (Eg), exciton binding energy (Ex), and binding energy of impurity bound excitons (EBX) in h-BN epilayers. Excitonic parameters of h-BN epilayers grown by MOCVD, carbon-free chemical vapor deposition, and high purity h-BN bulk materials are compared and discussed. The present results, together with available information in the literature, represent a significant improvement in the understanding of the fundamental optical properties and excitonic parameters of h-BN ultrawide bandgap semiconductors.

Hexagonal boron nitride fibers as ideal catalytic support to experimentally measure the distinct activity of Pt nanoparticles in CO2 hydrogenation

Catalytic studies aim to design new catalysts to eliminate unwanted by-products and obtain 100 % selectivity for the preferred target product without losing activity. For this purpose, understanding the role of each component building up the catalyst is essential. However, determining the intrinsic catalytic activity of pure metals, especially precious metals in the CO2 hydrogenation reaction under ambient conditions is complex. This is because the catalyst supports used thus far always influence the catalytic process either directly or indirectly due to interface formation that modifies the electronic and morphological structure of the metals. Even SiO2, regarded as inert shows some activity owing to the hydroxyl groups on its surface. In this work, we propose chemically inert and defect-free hexagonal boron-nitride fibers (BNF) synthesized via a co-precipitation method with wide band gap and robust covalent bonds as an uncommon reference catalyst support to evaluate the catalytic activity of size-controlled Pt nanoparticles (4.7 ± 0.6 nm) in the hydrogenation of CO2. The fibers alone show no catalytic activity; however, Pt/BNF exhibited low but notable activity of 377 nmol/g at 400 °C and the catalyst can achieve nearly 100 % CO selectivity. X-ray photoelectron spectroscopy, transmission electron microscopy, and diffuse reflectance infrared Fourier transform spectroscopy measurements were used to indicate that hexagonal boron-nitride affects neither the metal nanoparticles nor the reaction itself; the measured catalytic activity stems from the activity of Pt deposites without the effect of the support, as they were alone. CO vibration spectroscopy studies suggest that due to the lack of substrate-metal interaction, Pt nanoparticles adopt an ideal spherical structure, resulting in several low coordination sites capable of CO2 conversion. Thus, BNF is proposed in the present article to be used as a reference catalyst support material. It can be efficiently used in investigations involving the proposed metal and reaction or under varying conditions with different metal nanoparticles and reaction systems.

Effects of hexagonal boron nitride nanosheets on the biostabilization of recycled sands for geotechnical fill applications

Biostabilization techniques including plant enzyme induced calcite precipitation (EICP) and microbially induced calcite precipitation (MICP) represent promising and environmentally friendly methods for improving the engineering properties of recycled geomaterials for geotechnical fill applications. In this study, hexagonal boron nitride (h-BN) nanosheets were dispersed and utilized as nano-additives in the EICP and MICP reaction processes to facilitate the precipitation of calcium carbonate polymorphs (CaCO3) in washed recycled sands (RS) derived from construction and demolition (C&D) wastes for geotechnical fill applications. The investigation comprised a systematic range of biological and chemical microscopic and macroscopic experiments intending to stabilize the RS for geotechnical fill applications. The study results suggested that using h-BN nanosheets did not have a notable impact on bacterial growth or the functioning of bacterial and plant enzyme activity. In addition, it was observed that the optimal addition of h-BN nanosheet additives substantially increased CaCO3 precipitation by up to 34 % and 28 % in the EICP and MICP reaction processes respectively, which can be postulated to be due to the nanosheets acting as nucleation sites throughout the high surface area and negatively surface charge. Furthermore, the introduction of h-BN nanosheets led to a significant enhancement in the performance of unconfined compressive strength (UCS) of the stabilized RS through nanofillers and reinforcements, with improvements of up to 20 % and 13 % in the biostabilization of RS using the EICP and MICP after 10 treatment cycles. Detailed analyses, including Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) imaging, revealed that h-BN nanosheets, with a substantial surface area and effective chemical functional groups, interconnected with the CaCO3 mineral surface. Overall, the study suggests that integrating effective additives can improve the utilization of EICP and MICP in geotechnical fill applications, namely in road embankments and pavements, whilst providing both commercial viability and enhanced performance.

Integration of metal co-dopted cysteine builted in porous covalent organic framework (COF) decorated 2D hexagonal boron nitride (h-BN) for multi-functional smart coatings

Advanced multi-functional epoxy coating with physical barrier/shielding against corrosive species, self-repairing-capability/active anti-corrosive behavior, abrasion resistance, and thermomechanical durability was established in this study. For this purpose, zinc/l-cysteine (ZC) inbuilt pH-sensitive covalent organic framework (COF) decorated two dimensional (2D) layered amino-functionalized (Si) oxidized hexagonal boron nitride (ZC-COF-Si-Oh-BN) container was prepared. Different analyses such as FT-IR, XRD, BET, XPS, TGA, TEM, and FE-SEM were utilized to evaluate the synthesized containers and pristine materials. To figure out the function of entry of the ZC-COF-Si-Oh-BN container into the epoxy coating (EC/ZC-COF-Si-Oh-BN), the EIS, salt spray (SS), cathodic disbondement (CD), pull-off adhesion, Taber abrasion, and dynamic mechanical thermal analysis (DMTA) tests were employed. The results revealed that the introduction of the ZC-COF-Si-Oh-BN container into the neat epoxy polyamide coating (EC) improved the physical barrier protection with a value of log |Z| 10mHz equal to 10.22 even after too long soaking time of 112 days in the saline solution (3.5 wt% of sodium chloride), and recovery-capability/active anti-corrosive behavior with 20.6 % healing degree after 7 h of soaking time. The abrasion weight loss for the EC and EC/ZC-COF-Si-Oh-BN coatings after 2000 abrasion cycles was about 4.8, and 4.1 mg, respectively, with 14.5 % improvement in abrasion resistance.

Surface enhanced Raman scattering-based sensing and ultrafast nonlinear optical properties of silver-hexagonal boron nitride nanocomposites achieved by femtosecond laser ablation

This study investigated the surface-enhanced Raman spectroscopy (SERS) properties and nonlinear optical (NLO) behavior of silver nanoparticles (Ag NPs) decorated hexagonal boron nitride (hBN) nanocomposites. Although Ag NPs are known for their excellent plasmonic properties, their susceptibility to oxidation in ambient conditions significantly reduces SERS activity. To overcome this, a femtosecond laser-assisted single-step novel approach is developed for synthesizing hybrid Ag-hBN nanocomposites via ablating Ag target in a solution of exfoliated hBN nanosheets, forming uniformly embedded Ag NPs on hBN nanosheets. The morphological characteristics and elemental compositions were validated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). TEM analysis revealed that Ag NPs averaged 15 nm in size, while hBN nanosheets had lateral dimensions of approximately 250 nm. The SERS activity of the prepared nanocomposites was investigated using dye and explosive molecules, achieving detection sensitivities of 1 μM and 100 μM, respectively, with high reproducibility. These detection sensitivities are significant as they demonstrate the potential of the Ag-hBN nanocomposites for sensitive and reliable detection of trace amounts of analytes. Notably, the Ag-hBN nanocomposites showed enhanced SERS activity compared to pure Ag NPs, with a 2.5-fold improvement for Nile blue, 3.6-fold for methylene blue, and 2.4-fold for RDX. The current study also demonstrates that hBN prevents Ag NPs’ oxidation and preserves the SERS functionality even at elevated temperatures. Furthermore, the NLO properties of the nanocomposites were investigated using the standard Z-scan technique, revealing two-photon and three-photon absorption coefficients of 3 × 10−4 cm/GW and 6.5 × 10−5 cm3/GW2, respectively. The findings highlight the potential of Ag-hBN nanocomposites to enhance SERS and NLO devices, enabling future applications in sensing and photonics.

A polysulfides adsorption strategy through cation-anion interactions for achieving high-safety lithium-sulfur batteries in multiple scenarios

The widespread application of lithium-sulfur batteries (LSBs) is hindered by challenges such as the shuttle effect of polysulfides (LiPSs), slow reaction kinetics, and fire safety concerns. In this study, surface-functionalized boron nitride nanosheets (ChBN) are prepared and employed as functional separator coatings, enabling multiple application scenarios of LSBs. Specifically, a creative strategy of cation-anion interactions is constructed through the strong chemisorption of N+ on the ChBN surface to Sn- in LiPSs. In addition, the boron nitride and N+ show synergistic effects on adsorption-catalysis, further facilitating the rapid and sufficient deposition of Li2S. The prepared LSBs with ChBN + SP/PP separators exhibit excellent cycle stability (an ultralow capacity degradation of 0.034 % per cycle over 500 cycles at 2C). These LSBs are available in a wide temperature range of −20 to 60 °C, offering a capacity of 1208 mA h/g at 60 °C and 919 mA h/g at −20 °C. Furthermore, the presence of ChBN effectively improves the fire-safety of pouch batteries through the condensed-phase flame retardant mechanism. This simple fabrication process of ChBN is effective and favorable for large-scale manufacturing, which provides a feasible method for the development of high-safety LSBs.