Boron Nitride Nanosheets Research Articles

Polymeric Nanocomposites of Boron Nitride Nanosheets for Enhanced Directional or Isotropic Thermal Transport Performance.

Polymeric composites with boron nitride nanosheets (BNNs), which are thermally conductive yet electrically insulating, have been pursued for a variety of technological applications, especially those for thermal management in electronic devices and systems. Highlighted in this review are recent advances in the effort to improve in-plane thermal transport performance in polymer/BNNs composites and also the growing research activities aimed at composites of enhanced cross-plane or isotropic thermal conductivity, for which various filler alignment strategies during composite fabrication have been explored. Also highlighted and discussed are some significant challenges and major opportunities for further advances in the development of thermally conductive composite materials and their mechanistic understandings.

Gas sensitivity research of transition metal (Fe, Zr, Ta, Tc) doped boron nitride nanosheets to indoor toxic gases (CH2O, NH3, Benzene): A DFT perspective

Indoor air quality affects human health, with CH2O, NH3 and Benzene being the three most common indoor toxic gases. In this work, we investigated the adsorption of transition metal (Fe, Zr, Ta, Tc) doped boron nitride nanosheets (BNNSs) for three indoor toxic gases based on density functional theory (DFT). Through a series of analyses after simulation, the results show that the adsorption of pristine BNNSs for the three toxic gases is low, whereas the adsorption of transition metal doped BNNSs for all the three gases are significantly enhanced. Among them, Ta-BNNSs is the structure with a large change in band gap after adsorption of CH2O and Benzene. For NH3, the band gap change after adsorption of Tc-BNNSs is the largest. We have analyzed the recovery time of these three adsorption systems at 298 K, 398 K and 498 K. The results showed that the recovery time of Ta-BNNSs for adsorption of CH2O or Benzene at all three temperatures was large, while the recovery time of Tc-BNNSs at 498 K was small. Thus Tc-BNNSs are a potentially recyclable NH3 sensor material. Finally, the relative adsorption energy analyses showed that Fe-BNNSs had large adsorption energies for all three toxic gases at room temperature and the desorption temperatures were all around 700 K. Therefore, Fe-BNNSs are promising as a recyclable adsorbent material for the three toxic gases.

Dimethyl sulfoxide dispersion of aramid nanofibers: An excellent medium for exfoliating high-quality boron nitride nanosheets towards heat spreading films with high thermal conductivity

Herein, we used dimethyl sulfoxide (DMSO) dispersion of aramid nanofibers (ANFs) as medium to exfoliate boron nitride nanosheets (BNNSs) from their bulk materials via a ball-milling route. The obtained BNNSs displayed large lateral sizes and were very clean without any contaminants. When milling under a high energy condition, many small-area nanosheets were appeared but the sample produced with high ANF concentration could still contain more large-size BNNSs. It was concluded that the DMSO is a good exfoliating medium for BNNSs due to the suitable viscosity, molecular weight, and polarity, while the introduction of ANFs can further improve the exfoliated sizes of BNNSs because of the buffering to impacting forces of milling balls. The ANF/BNNS composite exfoliated under high energy ball-milling and high ANF concentration gained the highest in-plane thermal conductivity of 27.23 W m−1 K−1 since the densified microstructure and the high dispersity, large lateral size, and high horizontal orientation of BNNSs.

Significantly enhancing the through-plane thermal conductivity of epoxy dielectrics by constructing aramid nanofiber/boron nitride three-dimensional interconnected framework

Epoxy dielectrics with high through-plane thermal conductivity (λ) hold great promise for applications in the thermal management of advanced power electronics. Intensive attempts have been made to improve the λ of epoxy by filling with boron nitride nanosheets (BNNSs). However, it remains a great challenge to achieve a satisfactory increased λ by a small amount of BNNS loading. Herein, we reported a new strategy to prepare epoxy dielectrics with internal three-dimensional phonon transport channels by vacuum freeze-drying and vacuum impregnation. Aramid nanofibers (ANFs) and BNNSs were used for the collaborative construction of a vertical interconnected thermal framework. The resultant ANF-BNNS/epoxy achieved a high through-plane λ of 0.87 W m−1 K−1 at only 1.43 vol. % BNNS, which is ∼17.1% higher than that of the BNNS/epoxy counterpart with even 18.34 vol. % randomly distributed BNNS. The increasing efficiency of λ of epoxy by ANF-BNNS is tenfold more than that of the conventional blending methods. In addition, the ANF-BNNS/epoxy composite also exhibits a low dielectric constant and low dielectric loss. The findings of this study offer an inspired venue to develop high-performance thermally conductive epoxy dielectrics with a minimal BNNS loading.

Injectable Boron Nitride‐Hyaluronic Acid Hybrid Hydrogels to Facilitate Joint Motion: Mechanical and Tribological Characterization

AbstractHexagonal boron nitride (hBN) is used as an additive in engineering applications such as polymers, ceramics, and coatings because of its anti‐wear and lubrication performance. It has a high potential as a biomaterial, but it has not been evaluated to facilitate joint motion with its lubricating properties until now. In this study, the hypothesis that boron nitride nanoparticles (BNPs) and nanosheets (BNNSs) can facilitate movement in the joint region is evaluated for the first time. Hyaluronic acid‐based hybrid hydrogels are designed to transport BN particles to the target area and pin‐on‐disc tests on cartilage pins paired with glass disks are conducted to determine the validity of the proposed hypothesis. The injectability, mechanical properties, and friction coefficients of hydrogels with the addition of increasing proportions of different hBN morphologies are monitored. As a result, hyaluronic acid has been found to be a suitable carrier for the injectability of boron nitride in biomedical applications. The amount and morphology of boron nitride are observed as two important parameters. A significant decrease in the friction coefficient (18.9%) is observed in the BNNS‐doped hybrid hydrogel compared to the virgin hydrogel. hBN can be considered as a new therapeutic agent with the potential to facilitate joint mobility.

Interface engineering of polymer composite films for high-temperature capacitive energy storage

Polymer film capacitors encounter challenges in harsh conditions of high temperatures and electric fields because of large conduction loss and degraded breakdown strength (Eb). Herein, an interface engineering strategy is proposed to fluorinate the interfaces between the polyetherimide (PEI) matrix and wide bandgap boron nitride nanosheets (BNNSs) fillers. The composite films exhibit high-performance capacitive energy storage with a remarkable energy density of 5.73 J/cm3 and an ultrahigh efficiency of 91.22 % in conditions of 575 kV/mm and 150 °C. By adopting interfacial fluorination, the band structure of BNNSs is tailored to achieve a type II band alignment with PEI, promoting the dual trapping for both electrons and holes. It highly suppresses leakage current and reduces conduction loss. Typically, introducing fillers can compromise the properties of interfacial layers, creating weak points that trigger breakdown. Conversely, fluorinated interfaces exhibit an increased Young’s modulus and a reduced dielectric constant. According to the electromechanical breakdown theory, the interfacial Eb is increased. The breakdown phase propagation along the interfaces is thereby impeded, ultimately resulting in a further increase in overall Eb, reaching up to 589 kV/mm at 150 °C. Fluorinated interface engineering addresses interfacial challenges posed by fillers, enabling high-temperature energy storage capability in PEI-based capacitors.

Amorphous Boron Nitride Nanosheet‐Based Solid State Electrolytes with High Ionic Conductivity

AbstractAmorphous boron nitride nanosheets, with natural electrical insulation, outstanding chemical stability and mechanical properties, are introduced as a matrix to be incorporated with lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) and polymer polyvinylidene fluoride‐hexafluoropropylene copolymer (PVDF‐HFP), for constructing a novel composite solid‐state electrolyte by a simple solution‐casting method. Amorphous boron nitride nanosheets are produced via a combination method of ball milling and pure water exfoliation. The obtained composite solid‐state electrolyte containing 40 % (mass fraction) PVDF‐HFP shows a high lithium ion conductivity (1.936×10−3 S cm−1) and lithium ion transference number (0.47), and a wide electrochemical stability window (5 V) at room temperature. The LiFePO4/Li based all solid‐state battery, consisting of the composite solid electrolyte (40 % PVDF‐HFP), delivers a capacity of 128.1 mAh g−1, a Coulombic efficiency of 99.79 % after 500 cycles and a capacity retention rate of 94.5 % at 1.0 C and 25 °C. The composite solid electrolyte (40 % PVDF‐HFP) can maintain flat and stable stripping/plating plateaus for over 800 hours in symmetrical cells. The amorphous boron nitride nanosheets with high lithium ion conductivity are employed to construct solid‐state electrolytes, which is important significant for the development of high energy density, high safety, and long cycle life all‐solid‐state lithium‐ion batteries.

A novel biosensor based on Y2O3/BN composite for detection of lactate content in athlete training

A novel lactate biosensor based on a yttrium oxide/boron nitride (Y2O3/BN) nanocomposite modified electrode was developed. The BN nanosheets provided a supporting matrix for the Y2O3 nanoparticles, combining their synergistic properties for electrochemical biosensing. The Y2O3/BN nanocomposite provided high surface area and excellent electrocatalytic effects, promoting the oxidation of hydrogen peroxide generated from lactate oxidase catalyzed lactate oxidation. The Y2O3/BN modified biosensor showed wide linear range from 0.005 to 500 μM, low detection limit of 2 nM, high sensitivity of 1.23 μA/μM, good reproducibility with 3.2 % RSD, and long-term stability over 56 days. The biosensor could detect lactate levels in athlete sweat samples with high accuracy and correlation to standard methods, distinguishing changes in sweat lactate corresponding to different exercise intensities. The nanocomposite modified biosensor showed potential for non-invasive, real-time monitoring of exercise levels and fatigue status based on sweat lactate detection in athletic training applications.

High thermal conductivity and low dielectric loss of three-dimensional boron nitride nanosheets/epoxy composites

Electronic power devices are moving towards high frequency, high integration, and high power, which urgently needs to develop high thermal conductive encapsulating insulation materials to improve the heat dissipation of electronic devices. Herein, we propose to modify the commercialized encapsulating materials of epoxy resin (EP) by incorporating three-dimensional hydroxylated boron nitride nanosheets (3D-BNNSs). The cryogel and vacuum freeze-drying techniques are employed to prepare the 3D-BNNSs using agarose. The results show that the constructed high thermal conductive structure of 3D-BNNSs can effectively enhance the thermal conductivity of EP and reduce the interfacial thermal resistance between BNNSs fillers. The thermal conductivity of 3D-BNNSs/EP composites with 33.03 wt% BNNSs reach 2.54 W/(m·K), which is 13.11 times higher than that of EP (0.18 W/(m·K)). Meanwhile, the resultant composites remain outstanding electrical insulation and dielectric properties. Because agarose contains numerous hydroxyl groups that can form hydrogen bonds with the hydroxyl groups on the surface-functionalized BNNSs, hydrogen bonding can lead to strong intermolecular interactions, which is conductive to accelarate phonon transport. Additionally, agarose can cross-link with the molecular chains of epoxy, impeding the movement of molecular chain segments and resulting in composites with low dielectric loss at high frequencies. This study demonstrates that the 3D-BNNSs/EP composites have great potential for application in thermal management of electronic components.

Research on the effect of DES properties on the preparation of h-BN nanosheets by electrochemical-liquid phase exfoliation method

Hexagonal boron nitride (h-BN) with a large specific surface area and unique optoelectronic properties has good application prospects in many fields. The liquid phase exfoliation method is considered the most promising method for achieving controllable preparation of boron nitride nanosheets (BNNSs), but the low-cost, relatively environmentally friendly and efficient liquid phase exfoliation is still difficult to achieve. Choosing a suitable solvent system is the key to achieving efficient exfoliation. Deep eutectic solvents (DESs) have the advantages of simple synthesis, low cost, high thermal and chemical stability and strong biocompatibility and are expected to be green solvents for preparation of BNNSs. In this paper, it was found that the properties of DESs and its interaction with h-BN had a significant impact on the electrochemical exfoliation of h-BN. The intercalation effect of DES and the compatibility between DES and h-BN were the main factors affecting the yield, while the quality of BNNSs mainly depended on the decomposition and expansion effect of DES. This rule also can be applied to prepare highly conductive and hydrophilic two-dimensional material Ti-MXene. This research explores the structure–activity relationship between two-dimensional materials and DESs, and provides a theoretical basis for the environmentally friendly and efficient preparation of two-dimensional materials using DESs as exfoliation solvents.

Enhanced mechanical properties of boron carbide ceramics prepared by spark plasma sintering with boron nitride nanosheets addition

Boron carbide (B4C) ceramics with enhanced mechanical properties have been fabricated with boron nitride nanosheets (BNNSs, 1.5–5 wt%) as reinforcement via spark plasma sintering. The densification temperature of the B4C ceramic containing 3 wt% BNNSs (B4C-3 %BNNSs) was reduced to 1480–1700 °C, approximately 100 ℃ lower than the pure B4C ceramic. The B4C-3 %BNNSs composites with a density of 98.9 % and associated Vickers hardness of 34.4 GPa, flexural strength of 654 MPa, and fracture toughness of 4.86 MPa·m1/2 that represent a respective increased by 1.1 GPa (3.3 %), 178 MPa (37.4 %) and 1.57 MPa·m1/2 (47.7 %) relative to pure B4C. The reinforcement mechanisms due to BNNSs combined with B4C involves a synergistic effect of the decrease in densification temperature where the BNNSs promote B4C grain rearrangement, B4C twin grain boundaries, and BNNSs pull-out, crack branching and crack deflection effects.

Highly thermal conductivity polymer composites reinforced by BNNS/UHMWPE fabric for reliable electronic thermal protection and management

With the rapid development of 5G communication and microelectronics technology, the heat accumulation of high-power electronic devices puts forward an urgent demand for high thermal conductivity (TC) composites. However, it's still a great challenge through electrically insulating polymer to achieve good comprehensive performance of high TC, flexibility, and safety reliability. Herein, ultra-high molecular weight polyethylene (UHMWPE) fabric was coated with boron nitride nanosheets (BNNS) by dispersion and interfacial reinforcement of cellulose nanofibers (CNFs), and the BNNS/UHMWPE fabric-reinforced polymer composite (B/UF-PC) with 3D continuous thermal pathway was obtained by further composite with polydimethylsiloxane (PDMS). The continuous thermal pathways of highly aligned UHMWPE fibers in the fabric and the synergistic effect of the BNNS network enhance the out-of-plane and in-plane TC to 6.02 and 11.78 W/m K, respectively. Moreover, B/UF-PC exhibits flexible, lightweight (0.89 g/cm3), and significantly higher tensile strength (87.40 MPa) and energy absorption efficiency (98 %) than those of polymer composites, which allows it to be used in reliable electronic thermal management to prevent heat accumulation and external mechanical impact. This work provides a strategy for efficiently preparing flexible polymer composites with high TC and insulation properties.

Mechanochemical exfoliation of sugar-assisted boron nitride nanosheets for achieving superlubricity and wear distinction

Boron nitride nanosheets (BNNS) possess extensive potential applications across various fields. However, their limited dispersibility in liquids constrains their effectiveness as lubricating additives. In this study, a streamlined sugar-assisted mechanochemical exfoliation technique was employed to concurrently exfoliate and functionalize BNNS. This approach enabled the covalent grafting of sucrose molecules onto BNNS, enhancing their dispersion in water. The application of water containing sucrose-modified BNNS (S-BNNS) facilitated an ultralow coefficient of friction (COF = 0.001) at the Si₃N₄-Si₃N₄ interface. Additionally, using S-BNNS nanosheets as lubricating additives in water achieved superlubricity with a significant surface roughness (Ra ≤120 nm). We explored the correlation between surface roughness and superlubricity, revealing that tribological performance was enhanced by the formation of a tribofilm composed of S-BNNS and a silica layer at the interface through tribochemical reactions. The exceptional anti-wear properties and significantly reduced shear strength of S-BNNS within the tribofilm substantially contributed to achieving the ultralow COF, thus enhancing lubrication performance.

Stable energy storage performance at high-temperature of PESU-based dielectric composite regulated by SiO2 and BNNSs

Polymer dielectric capacitors are essential components for energy storage in modern electronic devices. They offer several advantages, including excellent voltage resistance, easy processing, and great energy storage density (U). However, with high thermal and electric fields, the more conductivity losses of polymer dielectric materials can be generated and aggregated, and the discharge energy density (Ue) and charging-discharging efficiency (η) of dielectric capacitor are usually significantly lower than that at room temperature. Here, the state-of-the-art composite is proposed, in which the SiO2 filler with excellent insulation strength is introduced into the middle composite layer, and the composite introduced wide band-gap boron nitride nanosheets (BNNSs) is used as the outer composite layer to inhibit carrier migration and reduce leakage current density of composite. The experimental results illustrate that the Ue of 1BP/1SP/1BP dielectric composite reaches about 9.37 J/cm3, and the η is around 82.0 % under the electric field of 540 kV/mm at 80 °C. Significantly, the η of multilayer 1BP/1SP/1BP composite remained >95.0 % after 50,000 cycles, indicating that this multilayer composite has good cycle stability and excellent reliability under a high-temperature. It presents a practical approach to enhance the energy storage performance of dielectric polymer at high-temperature environment.

Enhancing mechanical properties of cementitious composites by boron nitride nanosheets modified carbon fiber

Carbon fiber (CF) is commonly employed to enhance the mechanical properties, electrical conductivity, and electromagnetic absorption properties of cementitious composites. However, its weak interfacial bonding with the matrix limits its application in such composites. In this study, boron nitride (BN) nanosheets were synthesized via the solid-state reaction and used to modify CF surface. The flexural and compressive strengths of cementitious composites incorporating BN nanosheets coated CF (BN@CF) increased by 18.45 % and 29.38 %, respectively, with CF doping at only 0.2 wt%. Isothermal calorimetry and TGA results revealed that BN nanosheets on CF surface would provide nucleation sites for the formation of C–S–H and CH. The microstructure and bonding properties of BN@CF were characterized using SEM/EDS, FTIR, XPS, finite element analysis, and single fiber pullout test. The results showed that the significant improvement of interfacial properties between the fiber and the matrix contributed to the increase of mechanical properties of cementitious composites. These findings provide an effective strategy for the strength development of CF-reinforced cementitious composites.

Giant electrocaloric effect and breakdown field strength in ferroelectric terpolymer nanocomposites by morphologically diverse nanostructures

Electrocaloric cooling is a method for flexible electronics and compact chips with a promising ability to subvert traditional vapor compression refrigeration technology. Nevertheless, most reported EC materials exhibit relatively low adiabatic temperature (ΔT) and low breakdown field strength (Eb) at room temperature, limiting their further applications. Here, we develop a ferroelectric nanocomposite, composed of relaxor terpolymer poly(vinylidene fluoride-trifluoroethylen-chlorofluoroethylene) (PVTC), ceramic nanofillers [0.68(BaZr0.2Ti0.8O3)-0.32(Ba0.7Ca0.3TiO3)] (BCZT), boron nitride nanosheets (BNNSs), and BiFeO3 nanofibers (BFO NFs) with different morphologies and vary components ratios. The most optimal 12BBBP nanocomposite demonstrates gigantic ECE values including an isothermal entropy change (ΔS) of 94.5 J·kg−1·K−1 and a ΔT of 13.5 K under 220 MV/m electric field at 303 K, ΔS and ΔT are 3.5 times and 2.2 times larger than PVTC under 100 MV/m. It also exhibits an excellent Eb with a value of 290 MV/m. The phase-field simulation is used to simulate Eb behavior of nanocomposites with fillers of different nano-morphologies under an electrostatic field. Simultaneously, the interfacial coupling and ferroelectric domain structures are also simulated based on the time-dependent Landau-Ginzburg-Devonshire (TLGD) theory through finite element analysis (FEA) to present a better explanation for ECE performance. The experimental and simulation results simultaneously denote the ferroelectric nanocomposite possesses outstanding ECE and high Eb performance, laying foundation for the ferroelectrics in fields of flexible electronics and compact chip cooling. Coupled with the facile processability of terpolymer and lead-free nature of electroactive ceramics, this work paves a new way to develop a scalable, environmentally friendly and high-performance EC materials for next generation of refrigeration.

Improved hot workability of TiAl composite with core-shell structure via in-situ synthesized multi-phases ceramic particles

TiAl composite with core-shell structure was in-situ synthesized incorporating BN nanosheets and graphene oxide into TiAl alloy using SPS, and the hot deformation behaviors were subsequently investigated on a Gleeble-1500D thermal simulation machine. The microstructural evolution and the influence of ceramic particles on hot deformation were revealed using OM, SEM, TEM, and EBSD. The results demonstrated a refined microstructure of TiAl composite induced by ceramic particles providing extra nucleation sites for DRX, contributing to lower flow stress, with peak stresses of 387 and 360 MPa for TiAl alloy and TiAl composite deformed at 1200 °C/1s−1, respectively. Moreover, dislocation slip was inhibited by ceramic particles leading to dislocation pile-up, facilitating the nucleation and growth of DRX at lamellar colony boundaries and α2/γ interfaces. Notably, the “shell” composed of TiB2 and Ti2AlN nanoparticles coordinated the deformation of lamellar colonies with different orientations, improving the hot workability of TiAl composite.

Nacre-inspired flexible and thermally conductive phase change composites with parallelly aligned boron nitride nanosheets for advanced electronics thermal management

Phase change materials (PCMs) are widely applied in passive thermal management and energy storage fields because of their large latent heat capability near phase transition points. However, molten leakage, inherent rigidity, and low thermal conductivity limit the thermal management applications of PCMs. In this work, a scalable doctor-blading technique was developed to prepare anti-leakage, flexible, and highly thermally conductive PCM composites. Paraffin wax (PW) works as the thermal energy storage unit, polydimethylsiloxane (PDMS) encapsulates the molten PW and imparts the composites with flexibility, and 1-Butyl-3-methylimidazolium Hexafluorophosphate (BMIMPF6)-modified boron nitride nanosheets (BPs) ensure high thermal conductivity. BPs were firstly achieved from bulk boron nitride (BN) powders and BMIMPF6 ionic liquid (IL) by the one-step ball milling process, then high-oriented alignment of BPs in PDMS/PW matrix was obtained by the strong shearing forces along the blade-casting direction. Owing to the high quality of BPs and interconnected structure of BPs network, the composites possessed high in-plane thermal conductivity of 2.87 W·m−1·K−1 at 15 wt% BPs, exhibiting a remarkable enhancement of 1494 % compared with PDMS/PW. The flexible composites showed effective heat dissipation performance by reducing the working temperature of smartphones over 11 °C. Finite element analysis demonstrated that the parallel alignment of BPs network and the thermal energy buffering of PW were crucial for improving the thermal management capability. Furthermore, the PDMS/PW/BP composites exhibited excellent flame-retardant and electrically insulating properties. This work provides a feasible method to prepare high-performance PCM composites, which show great application prospects in the thermal management of electronic devices.

Ultrahigh Dielectric Energy Density and Efficiency in PEI‐Based Gradient Layered Polymer Nanocomposite

AbstractDielectrics with high‐energy‐storage performance are highly desired for increasing compact‐size energy storage, and integration of modern power electronics. However, an ever‐existing challenge is to achieve both high efficiency (η) and high energy density (Ue). Here, a gradient‐layered (five‐layer) polyetherimide (PEI)‐based nanocomposite is presented. Different from traditional layered structures (modulation of filler volume fraction), multistage gradient interfaces are constructed by modulating the particle sizes of barium titanate nanoparticles (BaTiO3 NPs) to decrease sequentially from top to bottom. In this structure, three BaTiO3 NPs/PEI layers are clamped by two boron nitride nanosheets (BNNSs)/PEI layers. It is demonstrated that the gradient structure can suppress breakdown and confer high interfacial polarization, simultaneously. Consequently, the nanocomposite possesses an enhanced Ue of 16.38 J cm−3, and an ultrahigh η of 97.79%, far exceeding previously reported polymer nanocomposites. Furthermore, this nanocomposite also demonstrates satisfactory high‐temperature energy storage performances, achieving a Ue of 7.36 J cm−3 and an η of 83.12% at 150 °C. This gradient layered structure design opens a new way to explore high‐performance dielectric polymer nanocomposite with both ultrahigh Ue and η.

Fiber Optic Sensor Coated with Multiple Layers of Hexagonal Boron Nitride Nanosheets (BNNS) for the Detection of Volatile Organic Compounds.

Nowadays, volatile organic compound (VOC) detection is imperative to ensure environmental safety in industry and indoor environments, as well as to monitor human health in medical diagnosis. Gas sensors with the best sensor response, selectivity, and stability are in high demand. Simultaneously, the advancement of nanotechnology facilitates novel nanomaterial-based gas sensors with superior sensor characteristics and low power consumption. Recently, boron nitride, a 2D material, has emerged as an excellent candidate for gas sensing and demonstrated exceptional sensing characteristics for new-generation gas sensing devices. Herein, ultrathin porous boron nitride nanosheets (BNNSs) with large lateral sizes were synthesized using a facile synthesis approach, and their material characteristics were investigated utilizing a variety of analytical techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. A BNNS-coated cladding-modified fiber optic sensor (FOS) probe was prepared and employed for VOC (ammonia, ethanol, and acetone) sensing across concentrations varying from 0 to 300 ppm. The BNNSs-coated FOS demonstrated better selectivity toward 300 ppm ammonia, and specifically annealed BNNSs displayed a maximum sensor response of 55% along with a response/recovery times of 15 s/34 s compared to its counterparts. The superior ammonia sensing performances could be attributed to the formation of ultrathin nanosheets and a porous surface with slit-like features in hexagonal boron nitride.