Boron Nitride Nanoplates Research Articles

Pyramid Textured Photonic Films with High-Refractive Index Fillers for Efficient Radiative Cooling.

Sub-ambient cooling technologies relying on passive radiation have garnered escalating research attention owing to the challenges posed by global warming and substantial energy consumption inherent in active cooling systems. However, achieving highly efficient radiative cooling devices capable of effective heat dissipation remains a challenge. Herein, by synergic optimization of the micro-pyramid surface structures and 2D hexagonal boron nitride nanoplates (h-BNNs) scattering fillers, pyramid textured photonic films with remarkable solar reflectivity of 98.5% and a mid-infrared (MIR) emittance of 97.2% are presented. The h-BNNs scattering filler with high thermal conductivity contributed to the enhanced through-plane thermal conductivity up to 0.496W m-1 K-1 and the in-plane thermal conductivity of 3.175W m-1 K-1. The photonic films exhibit an optimized effective radiative cooling power of 201.2W m-2 at 40°C under a solar irradiance of 900W m-2 and a daily sub-ambient cooling effect up to 11°C. Even with simultaneous internal heat generation by a 10W ceramic heater and external solar irradiance of 500W m-2, a sub-ambient cooling of 5°C can be realized. The synergic matching strategy of high thermal conductivity scattering fillers and microstructured photonic surfaces holds promise for scalablesub-ambient radiative cooling technologies.

Bioinspired Thermal Conductive Cellulose Nanofibers/Boron Nitride Coating Enabled by Co-Exfoliation and Interfacial Engineering.

Thermal conductive coating materials with combination of mechanical robustness, good adhesion and electrical insulation are in high demand in the electronics industry. However, very few progresses have been achieved in constructing a highly thermal conductive composites coating that can conformably coat on desired subjects for efficient thermal dissipation, due to their lack of materials design and structure control. Herein, we report a bioinspired thermal conductive coating material from cellulose nanofibers (CNFs), boron nitride (BN), and polydopamine (PDA) by mimicking the layered structure of nacre. Owing to the strong interfacial strength, mechanical robustness, and high thermal conductivity of CNFs, they do not only enhance the exfoliation and dispersion of BN nanoplates, but also bridge BN nanoplates to achieve superior thermal and mechanical performance. The resulting composites coating exhibits a high thermal conductivity of 13.8 W/(m·K) that surpasses most of the reported thermal conductive composites coating owing to the formation of an efficient thermal conductive pathway in the layered structure. Additionally, the coating material has good interface adhesion to conformably wrap around various substrates by scalable spray coating, combined with good mechanical robustness, sustainability, electrical insulation, low-cost, and easy processability, which makes our materials attractive for electronic packaging applications.

Boron nitride nanoplate-based strand exchange amplification with enhanced sensitivity and rapidity for quantitative detection of Staphylococcus aureus in food samples.

Staphylococcus aureus is one of the most common foodborne pathogens that can cause serious food poisoning and infectious diseases in humans. Standard identification approaches include nucleic acid amplification, but current amplification tools suffer from low amplification efficiency, resulting in the risk of low sensitivity and long detection time. Herein, boron nitride nanoplates (BNNPs) were chosen as an additive for enhancing the sensitivity and rapidity of strand exchange amplification (SEA), thereby successfully expanding the application of nucleic acid detection for detecting Staphylococcus aureus in food samples. As a result, SEA based on boron nitride nanoplates (BNNP-SEA) was employed for sensitive and rapid detection of foodborne pathogen Staphylococcus aureus. Compared with classical SEA, the BNNP-based SEA assay was more than 10-fold sensitive, and the detection time was reduced by 15 minutes. The optimized BNNP-based SEA shows a wide linear range from 40 pg to 50 ng in a diluted solution of the target DNA with a low detection limit of 40 pg. Moreover, the BNNP-based SEA achieves the quantitative detection of Staphylococcus aureus in different food samples (pork, beef, mutton, duck, milk and shrimp). In contrast to the classical SEA, the BNNP-based SEA method enabled sensitive and rapid detection of Staphylococcus aureus in the above food samples at concentrations as low as 5 × 103 CFU mL-1. The BNNP-based SEA assay is specific, sensitive and reliable, offering a valuable diagnostic technology for routine analysis in food safety research.

Flexible highly thermal conductive hybrid film for efficient radiative cooling

Radiative cooling is highly significant for carbon neutrality and sustainable development. Rapid development has been made for materials of radiative heat dissipation, applicable to sub-ambient and above-ambient cooling. However, scalable and low-cost approach for radiative cooling materials coupled with high thermal conductivity need to be further explored. Here, we present a design strategy for flexible highly thermal conductive hybrid film towards efficient radiative cooling. The proposed thermal conductive radiative cooler (TCRC) consists of interconnected polyvinylidene difluoride (PVDF) fibrous frameworks and randomly dispersed hexagonal boron nitride (h-BN) nanoplates via electrospinning and hot-pressing processes. Synergistic effects of spectral and thermal conductive properties endow the film with a high solar reflectivity of 0.92 in 250–2500 nm and a broadband mid-infrared (MIR) emissivity of 0.93 in 4–16 μm, while the thermal conductivity reaches over 10 W m−1 K−1. The radiative cooler demonstrates excellent above-ambient cooling performance (∼11 °C) with an effective cooling power of ∼80 W m−2, comparable to the most advanced reports. Besides, the film exhibits superior mechanical strength of 33 MPa and hydrophobicity with 140° contact angle. This work opens up a new avenue of radiative cooling for devices working under both above-ambient conditions.

Superior high-temperature strength-ductility of TiB2–Ti2AlN/TiAl composite with core-shell microstructure

Herein, a novel core-shell structured TiAl composite consisting of nanoparticles “shell” and a near fully lamellar “core” was designed using a Ti–48Al–2Nb–2Cr alloy and Boron nitride nanoplates. By tailoring microstructure and nanoparticles strengthening, the TiAl composite exhibited a superior combination of strength and ductility at high temperature, which achieved an ultimate tensile strength of 514.2 MPa and an outstanding fracture strain of 18.8 % at 850 °C.

A Versatile Strategy for Concurrent Passive Daytime Radiative Cooling and Sustainable Energy Harvesting.

Developing versatile systems that can concurrently achieve energy saving and energy generation is critical to accelerate carbon neutrality. However, challenges on designing highly effective, large scale, and multifunctional photonic film hinder the concurrent combination of passive daytime radiative cooling (PDRC) and utilization of sustainable clean energies. Herein, a versatile scalable photonic film (Ecoflex@h-BN) with washable property and excellent mechanical stability is developed by combining the excellent scattering efficiency of the hexagonal boron nitride (h-BN) nanoplates with the high infrared emissivity and ideal triboelectric negative property of the Ecoflex matrix. Strikingly, sufficiently high solar reflectance (0.92) and ideal emissivity (0.97) endow the Ecoflex@h-BN film with subambient cooling effect of ≈9.5°C at midday during the continuous outdoor measurements. In addition, the PDRC Ecoflex@h-BN film-based triboelectric nanogenerator (PDRC-TENG) exhibits a maximum peak power density of 0.5W m-2 . By reasonable structure design, the PDRC-TENG accomplishes effective wind energy harvesting and can successfully drive the electronic device. Meanwhile, an on-skin PDRC-TENG is fabricated to harvest human motion energy and monitor moving states. This research provides a novel design of a multifunctional PDRC photonic film, and offers a versatile strategy to realize concurrent PDRC and sustainable energies harvesting.

High-Performance, Multifunctional, and Designable Carbon Fiber Felt Skeleton Epoxy Resin Composites EP/CF-(CNT/AgBNs)x for Thermal Conductivity and Electromagnetic Interference Shielding.

In this work, high-performance epoxy resin (EP) composites with simultaneous excellent thermal conductivity (TC) and outstanding electromagnetic shielding properties are fabricated through the structural synergy of 1D carbon nanotubes and 2D silver-modified boron nitride nanoplates (CNT/AgBNs) to erect microscopic 3D networks on long-range carbon fiber (CF) felt skeletons. The line-plane combination of CNT/AgBNs improve the interfacical bonding involving EP and CF felts and alleviate the phonon scattering at the interface. Eventually, the TC of the EP composites is enhanced by 333% (up to 0.91W m-1 K-1 ) with respect to EP due to the efficient and orderly transmission of phonons along the 3D pathway. Meanwhile, the unique anisotropic structure of CF felt and exceptional insulating BNs diminishes the electronic conduction between CNT and CFs, which protects the through-plane insulating properties of EPcomposites. Furthermore, the EPcomposites present favorable electromagnetic shielding properties (51.36dB) attributed to the multiple reflection and adsorption promoted by the multiple interfaces of stacked AgBNs and heterointerface among CNT/AgBNs, CF felt and EP. Given these distinguishing features, the high-performance EP composites open a convenient avenue for electromagnetic wave (EMW) shielding and thermal management applications.

Mechanical Properties and Damage Behaviours of Polyurethane Composites Reinforced With BNNP and MWCNT Hybrid Nanoparticles

In recent years, with increasing engineering applications, structural adhesives have played an increasingly important role in joining both metallic and non-metallic components. Polyurethane is frequently used in the adhesive industry due to its morphological structure, versatile material, and excellent matrix material. In addition, by doping polyurethane with single/multi-walled carbon nanotubes and boron nitride nanoplates materials, the mechanical properties of the polyurethane adhesive can be further increased. This study aimed to increase the mechanical properties of PU (thermoset polyurethane), which is frequently used in adhesively bonded joints by addition of MWCNT (multi-walled carbon nanotubes), BNNP (boron nitride nanoplates). For this purpose, nanoparticles synergistic interaction was investigated by adding a mass of 0.25%, 0.35%, and 0.45% MWCNT into PU, which was reinforced by 0.5% BNNP before. Samples mechanical properties were determined by tensile test according to ASTM D638-10 standard, flexure test according to ASTM D790-02 standard, and Shore D test according to ASTM D2240 standard. All sample test results were graphed, and each graph was compared. Also, broken surfaces were analyzed by scanning electron microscopy (SEM) to examine the damage mechanism of nanoparticles.

Improved dielectric and mechanical properties of Ti3C2Tx MXene/silicone rubber composites achieved by adding a few boron nitride nanoplates

MXenes have attracted great attentions in the fabrication of dielectric polymer composites because of their excellent electrical conductivity. However, the high dielectric loss tangent would suppress the application of such polymer-based composites. Incorporating insulating fillers might be a solution. Herein, Ti3C2Tx MXene/silicone rubber (SR) composites incorporated with boron nitride (BN) nanoplates were prepared. The homogeneous distribution of fillers was obtained in the composites, which was also thermally stable up to 400 °C. Dielectric constant of 7.06 (2.54 times of pure SR) and dielectric loss tangent of 0.00131 were achieved when the filling contents of MXene and BN in SR composite were 1.2 wt% and 5 wt%, respectively. The improved dielectric constant can be ascribed to the enhanced interfacial polarization and the formation of conductive network, while the low dielectric loss tangent can be due to the insulating interlayers of BN which could inhibit the transfer of free electrons from conductive fillers to the insulating polymer matrices. BN/MXene/SR composites displayed improved mechanical properties (tensile stress of 671 kPa and elongation at break of 353%) and good flexibility (elastic modulus of 540 kPa) due to the low filling content of fillers. This work is promising for preparing dielectric polymer composites in applications of electronic devices.

Simultaneous optimization of the thermal conductivity and mechanical properties of epoxy resin composites through PES and AgNP functionalized BNs

In this work, polyether sulfone (PES) and silver nanoparticles functionalized boron nitride nanoplates (AgBNs) were adopted to simultaneously improve the thermal conductivity and mechanical properties of the epoxy resin (EP) composites. The 0D silver nanoparticles (AgNP), successfully manufactured by the reduction reaction of DMF and AgNO3, were conductive to increase the interfacial contact of 2D boron nitride nanoplates (BNs), thus also improving the heat conduction paths of AgBNs. SEM and optical microscopy observations revealed that the 3D continuous thermal conduction paths of AgBNs were constructed based on PES/EP bi-continuous phase structures, and were perfected as the AgBNs contents increased. Consequently, the thermal conductivity of PES-EP/AgBNs achieved a maximum value of 0.54 W m−1 K−1 at 10 wt% AgBNs loading, which was much higher than that of both EP/AgBNs (0.45 W m−1 K−1) and EP/BNs (0.36 W m−1 K−1) at the same filler content. Meanwhile, the fracture mode of PES-EP/AgBNs changed gradually from brittle to ductile, and PES-EP/AgBNs further exhibited satisfactory tensile strength, flexural strength and fracture toughness, in comparison with EP/AgBNs due to the introduction of PES. This approach reconciles efficiently the conflict of thermal conductivity and mechanical properties of epoxy resin composites, presenting conceivable applications in high performance thermal conductivity devices.

Shape influence on the tribological properties of hexagonal boron nitride nanoplates and nanospheres reinforced epoxy coating

Hexagonal boron nitride was known for its excellent lubricating capacity, however, the shape influence on the tribological properties of hexagonal boron nitride modified epoxy composite coatings was still a challenging requirement. Herein, the boron nitride nanoplates (BNNP) and nanospheres (BNNS) were modified by polydopamine to improve their dispersion in epoxy coatings and the shape influence of two nanoparticles on the tribological property was proved by the micro-morphologies of wear debris. When the mass content of polydopamine-modified BNNS was 0.25 wt%, the friction-reduction and anti-wear effects were the best, and the coefficient of friction and wear rate was reduced by 13.75% and 60.77%, respectively, compared with the pure epoxy coating. The ‘ball effect’ of BNNS provided rolling friction and the layer-structured debris exhibited good lubricating properties. The enhanced wear mechanism of BNNS provided wider potential application in the mechanical industry, automotive, aerospace, and infrastructure fields.

Sputter-grown hierarchical nitride (TiN & h-BN) coatings on BN nanoplates reinforced Al7079 alloy with improved corrosion resistance

A boron nitride nanoplates (BNNPs) reinforced aluminium alloy (Al7079) based ex-situ metal matrix (MM) nano-composite was successfully developed via mechanical stir casting process. This MM nano-composite shows better wetting and anti-corrosion properties in comparision of bare Al7079 alloy. To further enhance the aforementioned properties, two dissimilar hard coatings (TiN & h-BN) with hierarchal rough surfaces were employed on the BNNPs functionalized MM composite surface via a single-step PVD technique, which provide a tough barrier with non-wetting surface to prevent the base material from corrosion attack. The addition of these layers led to a significant change in physical, chemical, mechanical and anti-corrosion properties. The results also revealed the hydrophobicity of developed coatings with optical contact angle meter of TiNNCs and h-BNNPs surfaces ~102.1° and 141.6°, respectively. The collective results obtained from electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests revealed the one order higher corrosion resistance of h-BN coated sample than TiN coated sample under saline media (3.5 wt%). This coating may be a promising candidate in various applications, where the protection of materials against corrosion is necessary. • Development of BN nanoplates reinforced aluminum alloy (Al-7079) metal matrix by mechanical stir casting. • The MM nano-composite shows better wetting and anti-corrosion properties as compare to base Al7079 alloy. • TiNNCs and h-BNNPs were employed on the BNNPs-Al7079 composite surface via a single-step PVD technique. • Better hydrophobicity and high corrosion resistance shown by BNNPs coated sample compared to TiNNCs coated sample.

Nanoarchitectonics of BN/AgNWs/Epoxy Composites with High Thermal Conductivity and Electrical Insulation.

To promote the construction of the thermal network in the epoxy resin (EP), a certain proportion of silver nanowires (AgNWs) coupled with the hexagonal boron nitride (BN) nanoplates were chosen as fillers to improve the thermal conductivity of EP resin. Before preparing the composites, BN was treated by silane coupling agent 3-aminopropyltriethoxysilane (KH550), and AgNWs was coated by dopamine hydrochloride. The BN/AgNWs/EP composites were prepared after curing, and the thermal conductivity and dielectric properties of the composites was tested. Results showed that the AgNWs and BN were uniformly dispersed in epoxy resin. It synergistically built a thermal network and greatly increased the thermal conductivity of the composites, which increased 9% after adding AgNWs. Moreover, the electrical property test showed that the addition of AgNWs had little effect on the dielectric constant and dielectric loss of the composites, indicating a rather good electrical insulation of the composites.

Thermally conductive composites with hydroxylated boron nitrides for the efficient thermal management of superconducting coils

The thermal conductivity (κ) of polymer nanocomposites with boron nitride (BN) nanoplates is critically dependent on the distribution of BN in the polymer matrix. Here, we heavily functionalized BN nanoplates with hydroxyl groups by ultrasonication in solution with boric acid. Then, the hydroxylated BN nanoplates could be homogeneously distributed in an epoxy matrix, which improved the through-plane κ of 2.09 and 1.96 W/m·K at 25 and -90 °C, respectively. Processable composite resin with hydroxylated BN was utilized as an adhesive for a low-temperature superconducting (LTS) coil to enhance its normal zone propagation velocity (NZPV) and cooling rate performance. Consequently, fast heat dissipation through the adhesive between superconductors contributed to a 65.8% of increase in NZPV and a 13.1% improvement in the cooling rate of the device compared with a commercial adhesive.

High performance pliable supercapacitor fabricated using activated carbon nanospheres intercalated into boron nitride nanoplates by pulsed laser ablation technique

Pliable supercapacitor, yielding specific capacitance (Cs) and energy density as high as 348 F g−1 and 48.3 Wh Kg−1 respectively was fabricated using modified activated carbon electrodes. The nanospheres of activated carbon (AC) were anchored on the nanoplates of boron nitride (BN) by employing the facile technique of pulsed laser ablation in liquid (PLAL) using 532 nm focused laser beam. Four different variants of electrode materials were synthesized by varying the weight percentage (1%, 3%, 5% and 10%) of BN in AC in the PLAL precursor solution. The morphological characteristics, the elemental composition and the structural analysis of the synthesized electrode materials were studied respectively by FESEM, XPS and XRD. The morphological studies indicated that the PLAL synthesis of the electrode materials resulted in proper intercalation of carbon nanospheres into BN nanoplates, which resulted in the observed enhanced performance of the fabricated supercapacitor. Four supercapacitors in this work were fabricated using the four variants of synthesized electrode materials in conjunction with gel polymer electrolyte (GPE). GPE are well known for their non-corrosive nature and best sealing ability to avoid any leakage that results in increasing the cycle life of the device. The performance of the fabricated supercapacitors was evaluated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) measurement and electrochemical impedance spectroscopy (EIS). The results indicate that the supercapacitor fabricated using 3% BN in AC as electrode material manifested the best specific capacitance and energy density. Also it was found that the supercapacitor maintained 85% of its initial capacitance even after 5000 charge/discharge cycles.

Combustion synthesis of hexagonal boron nitride nanoplates with high aspect ratio

High crystalline hexagonal boron nitride nanoplates with high aspect ratio of ~400 have been synthesized by combustion synthesis method through magnesiothermic reduction reaction between B2O3 and Mg in N2 pressure. The synthesized hexagonal boron nitride nanoplates were about 50 nm in thickness and larger than 20 μm in lateral size. The six-fold symmetric spots electron diffraction pattern of transmission electron microscopy shows that the nanoplate is well crystallized. Hexagonal boron nitride nanoplates grow via an Oswald ripening process and have larger lateral size when it was prepared with larger magnesium particles. High temperature liquid magnesium provides an important environment for the growth and crystallization of boron nitride. This work provides an effective way to achieve low-cost and large-scale preparation of high-quality boron nitride nanoplates.

Mass production of high thermal conductive boron nitride/nanofibrillated cellulose composite membranes

Boron nitride nanoplates (BNNPs) are highly desirable in thermal management applications. To achieve better performance, boron nitride (BN) has to be extensively exfoliated and dispersed in liquids. However, most of current techniques suffer from being high in cost, time consuming, and environmentally unfriendly, which limits the mass production of BNNPs for a wide range of applications. Herein, we demonstrate a simple yet green manufacturing process for efficient exfoliation and dispersion of BN and bamboo cellulose via stress-induced simultaneous exfoliation/dispersion (SISED) in an aqueous medium. This method can produce well exfoliated BNNPs/ nanofibrillated cellulose (NFC) with the average BNNPs thickness of 51 nm and NFC diameter of 43 nm after only 1.98 h treatment. Thanks to the excellent dispersion, heat-conducting and electric-insulating BNNPs/NFC nanocomposite membranes with an BNNPs content of 40 wt% are fabricated through vacuum-assisted filtration. The micro-structures of the membranes as well as their mechanical and thermal properties can be tailored by changing the refining time and the pan gap to meet different needs. The resultant membranes exhibit high mechanical properties with a tensile strength of 74.6 MPa and excellent thermal conductivity of 20.64 W m−1 K−1, suggesting their great potential in fabricating next-generation portable electronics.

Defect-related high temperature ferromagnetism in mechanically milled hexagonal boron nitride nanoplates

We report a high Curie temperature ferromagnetism in milled hexagonal boron nitride (h-BN) nanoplates. The nanoplates with different sizes were synthesized via high-energy ball milling method. The magnetization versus magnetic field curves clearly indicate that the milled h-BN nanoplates exhibit distinct ferromagnetism, and their saturation magnetization increases monotonically from 0.015 to 0.032 emu/g with increasing of milling time at room temperature, while the bulk BN powders present diamagnetism. Besides, the temperature-dependent magnetization curve shows that the Curie temperature of the milled h-BN nanoplates is greater than 900 K. Meanwhile, Combined with the results of X-ray diffraction, high-resolution transmission electron microscope, X-ray photoelectron spectroscopy, Raman, and Electron spin resonance, the ferromagnetic behaviors of milled h-BN samples are attributed to nitrogen defects on the surface. Furthermore, the nitrogen defects on surface of h-BN can induce ferromagnetic states, which can be confirmed by the first principle calculation. The performance of high temperature ferromagnetism in h-BN material makes it promising candidates for application in spintronic devices.

Chemoselective hydrogenation of nitrobenzenes activated with tuned Au/h-BN

The azo- and hydrazo compounds are of great importance in pharmaceuticals, agrochemicals, and chemistry. The controlled reduction of nitroarenes to their coupled products such as aromatic azo and hydrazo compounds has been an interesting area of research synthetically and mechanistically. Herein, we report that the chemoselective catalytic hydrogenation of nitrobenzenes to hydrazobenzenes via azobenzenes can be achieved over gold nanoparticles supported by hexagonal boron nitride nanoplates. It is found that the catalytic process can be successfully conducted not only in N2 but also in air with isopropanol alcohol/KOH. Complete conversion of nitrobenzenes and high selectivity of azobenzenes and hydrazobenzenes have been achieved in one pot under N2 or air atmosphere. Furthermore, as usual unstable intermediates in the reduction process of nitrobenzenes, azobenzenes and hydrazobenzenes can be alternatively harvested as the main product by controlling reaction time or atmosphere. This work shows promise for direct and chemoselective synthesis of azo- and hydrazo compounds under mild conditions in a controllable manner.

Effects of 2D boron nitride (BN) nanoplates filler on the thermal, electrical, mechanical and dielectric properties of high temperature vulcanized silicone rubber for composite insulators

Degradation of the silicone rubber in the composite insulators is usually caused by thermal and electrical stressing. The thermal conductivity of the composite insulator can be improved by adding a second phase with high thermal conductivity. Boron nitride is a new kind of two-dimentional (2D) materials, with a microstructure similar to the popular graphene but electrically insulating. Such unique properties make BN a promising candidate for increasing the thermal conductivity while maintaining the electrical insulating properties of the silicone rubber. In this report, we systematically studied the effects of BN nanoplates as a filler on the thermal diffusivity/conductivity, electrical breakdown strength, mechanical performance, dielectric behavior, as well as hydrophobicity properties of high temperature vulcanized silicone rubber. A series of samples were prepared with different BN filler loadings up to 32 wt% (∼25 vol%). We found that after adding BN nanoplates the sample's thermal conductivity can be increased by 30%. Surprisingly the electrical breakdown strength and hydrophobicity were also improved by the BN filler. However, the mechanical strength was deteriorated to some extent. Our results provide new thoughts in optimizing the performance of the silicone rubber for composite insulators. More studies need to be done in order to reveal the effects of BN additives in real composite insulators.