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Novel Porous Boron Nitride Nanosheet with Carbon Doping: Potential Metal-Free Photocatalyst for Visible-Light-Driven Overall Water Splitting
摘要： The band gap of hexagonal boron nitride (h-BN) is far too wide for efficiently utilizing visible light, limiting its application in photocatalysis. The present study employs first principles calculations to demonstrate that the band gap energies of porous h-BN (p-BN) can be tuned by carbon doping to levels appropriate for the absorption of visible-light, and that the conduction band and valence band match well with the potentials of both hydrogen and oxygen evolution reactions. Importantly, a strategy of carbon doping to improve the energy level of valence band maximum is also proposed. Moreover, the carbon-doped p-BN exhibits good separation between photogenerated electrons/holes and structural stability at high temperatures. The DFT results help the design of high-performance two-dimensional photocatalysts that avoid the use of metals.
关键词： metal-free catalysts,photocatalyst,porous boron nitride nanosheets,overall water splitting,band structure engineering
更新于2025-09-23 15:22:29
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Enhanced electron field emission from nanocrystalline orthorhombic boron nitride films
摘要： Nanocrystalline orthorhombic boron nitride (oBN) thin films with an island-in-honeycomb morphology were prepared on graphite substrate by radio frequency (r.f.) magnetron sputtering. The Field emission (FE) measurement results indicated that the FE properties are significantly enhanced in oBN films compared to high quality cBN films, the turn-on electric field of oBN films is decreased from 17.0 V/μm to 6 V/μm, and the highest emission current density is increased from 2.8 × 10?? to 3 × 10?? A/cm2. The enhanced FE properties of the oBN films can be attributed to significant reduction in effective potential barrier caused by both protruded island-in-honeycomb morphology and honeycomb-like interconnected internal structure.
关键词： Semiconductors,Thin films,Electron field emission,Boron nitride,Physical vapour deposition
更新于2025-09-23 15:22:29
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Magnetic-field-dependent quantum emission in hexagonal boron nitride at room temperature
摘要： Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters, promising efficient photon extraction and atom-scale engineering, but observations of spin-related effects have remained thus far elusive. Here, we report room-temperature observations of strongly anisotropic photoluminescence patterns as a function of applied magnetic field for select quantum emitters in h-BN. Field-dependent variations in the steady-state photoluminescence and photon emission statistics are consistent with a spin-dependent inter-system crossing between triplet and singlet manifolds, indicating that optically-addressable spin defects are present in h-BN.
关键词： photoluminescence,room temperature,quantum emitters,magnetic field,hexagonal boron nitride,spin defects
更新于2025-09-23 15:22:29
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Chemical Vapor Infiltration of the Hexagonal Boron Nitride Interphase for SiC Fiber-Reinforced HP-Si<sub>3</sub>N<sub>4</sub> Matrix Composite
摘要： This work describes the processing of SiC fiber-reinforced Si3N4 matrix composites with boron nitride (BN) interphase. The BN interphase was processed by chemical vapor infiltration (CVI) with BF3/NH3 gaseous precursors. The BN interphase modification involved the continuous treatment of Hi-Nicalon SiC fibers. The relations between (i) the processing parameters, (ii) the mechanisms controlling the kinetics of the CVI of the BN, and (iii) the structure of the deposited BN are presented. A single- or multi-layer BN interphase can be produced depending on the CVI conditions imposed on the fibers during the continuous process. A surface reaction mechanism controlling the CVI promotes a smooth, isotropic BN coating. An anisotropic BN coating can be produced when the CVI kinetics are controlled by a mass transport mechanism. With a controlled temperature gradient, the BN interphase is then made by stacking successive isotropic and anisotropic layers.
关键词： SiC fibers (Hi-Nicalon),CVI,boron nitride interphase
更新于2025-09-23 15:22:29
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Electrical and Electromagnetic Interference (EMI) shielding properties of hexagonal boron nitride nanoparticles reinforced polyvinylidene fluoride nanocomposite films
摘要： The hexagonal boron nitride nanoparticles (h-BNNPs) reinforced flexible polyvinylidene fluoride (PVDF) nanocomposite films were prepared via a simple and versatile solution casting method. The morphological, thermal and electrical properties of h-BNNPs/PVDF nanocomposite films were elucidated. The electromagnetic interference (EMI) shielding properties of prepared nanocomposite films were investigated in the X-band frequency regime (8–12 GHz). The EMI shielding effectiveness (SE) was increased from 1 dB for the PVDF film to 11.21 dB for the h-BNNPs/PVDF nanocomposite film containing 25 wt% h-BNNPs loading. The results suggest that h-BNNPs/PVDF nanocomposite films can be used as lightweight and low-cost EMI shielding materials.
关键词： Hexagonal boron nitride,PVDF,SEM,EMI shielding,DSC,electrical properties
更新于2025-09-23 15:21:21
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Electronic structure of graphene nanoribbons on hexagonal boron nitride
摘要： Hexagonal boron nitride is an ideal dielectric to form two-dimensional heterostructures due to the fact that it can be exfoliated to be just a few atoms thick and its very low density of defects. By placing graphene nanoribbons on high quality hexagonal boron nitride it is possible to create ideal quasi-one-dimensional systems with very high mobility. The availability of high quality one-dimensional electronic systems is of great interest also given that when in proximity to a superconductor they can be effectively engineered to realize Majorana bound states. In this work we study how a boron nitride substrate affects the electronic properties of graphene nanoribbons. We consider both armchair and zigzag nanoribbons. Our results show that for some stacking configurations the boron nitride can significantly affect the electronic structure of the ribbons. In particular, for zigzag nanoribbons, due to the lock between spin and sublattice degree of freedom at the edges, the hexagonal boron nitride can induce a very strong spin splitting of the spin-polarized, edge states. We find that such spin splitting can be as high as 40 meV.
关键词： heterostructures,graphene nanoribbons,hexagonal boron nitride,spin splitting,electronic structure
更新于2025-09-23 15:21:21
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Effect of low-energy ion impact on the structure of hexagonal boron nitride films studied in surface-wave plasma
摘要： A high‐density surface‐wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low‐energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ～37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2‐bonded phase in the films characterized by Fourier transform infrared spectroscopy and X‐ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X‐ray reflectivity is retained relatively high with a slight dependence upon ion energy.
关键词： surface‐wave plasma,Fourier transform infrared spectroscopy (FTIR),chemical vapor deposition (CVD),hexagonal boron nitride (hBN),X‐ray diffraction (XRD),X‐ray reflectivity (XRR)
更新于2025-09-23 15:21:21
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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Field Emission Performance of Boron Nitride Nanotube Emitters According to Vacuum Pressure
摘要： Field emission performance of boron nitride nanotube filtration-transfer fabricated by simple method, were evaluated according to vacuum pressure to estimate its potential use for robust electron sources. Even though there is little change in the current density-electric field characteristics, the stability test for a relatively long time shows somewhat large degradation at a vacuum pressure of over 10-6 Torr. To investigate a key factor of the degradation, we changed the vacuum ambient from air to argon. Under argon ambient condition, the current degradation and fluctuation rates were almost the same as those measured under air ambient at a vacuum pressure of 10-5 Torr. Consequently, ion bombardment dominantly induced the current degradation of the BNNT field emitters rather than oxidation effect.
关键词： Boron nitride nanotube,field emitter,film emitter,cold cathode
更新于2025-09-23 15:21:21
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Structure, morphology and dielectric properties of hexagonal boron nitride nanoparticles reinforced biopolymer nanocomposites
摘要： Hexagonal boron nitride nanoparticles (h-BNNPs)/Chitosan (CS)/Hydroxypropyl methylcellulose (HPMC) based ternary nanocomposites were prepared using solution casting method and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analyses (TGA), Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). The dielectric properties of CS/HPMC/h-BNNP nanocomposite films were also investigated as a function of frequency and temperature and a maximum dielectric constant of ~1200 was achieved at 5 wt % of h-BNNP loading in CS/HPMC blend matrix. The results from the structural, morphological and thermal studies revealed good interactions between h-BNNPs, CS and HPMC.
关键词： Hexagonal boron nitride,dielectric studies,solution casting,biopolymers
更新于2025-09-23 15:21:21
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Self-assembled CdS@BN core-shell photocatalysts for efficient visible-light-driven photocatalytic hydrogen evolution
摘要： CdS@BN NRs core-shell photocatalysts for hydrogen evolution were synthesized by a solvothermal and chemical adsorption method. CdS NRs coated by 5 wt% boron nitride (BN) shell exhibited remarkably visible-light photocatalytic hydrogen evolution activity of up to 30.68 mmol g?1 h?1, nearly 6.79 times higher than that of pure CdS NRs, and the apparent quantum efficiency at 420 nm was 7.5%. Transmission electron microscopy showed the CdS NRs were coated with a thin (~5 nm) BN layer, which together with the hydrogen evolution results proved the photocatalytic ability of CdS NRs was significantly improved. The hydrogen evolution rate of CdS NRs coated by 5 wt% BN remained at 91.4% after four cycles, indicating the photocorrosion of CdS NRs was effectively alleviated. Moreover, the large and close coaxial interfacial contact between the CdS core and the BN shell was beneficial to the separation and transfer of photogenerated electron-hole pairs.
关键词： Core-shell structure,Photocatalytic hydrogen evolution,CdS Nanorods,Boron nitride
更新于2025-09-23 15:21:01