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Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride
摘要： Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h-BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2”) production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication.
关键词： monolayer,hexagonal boron nitride,transfer,2D materials,large crystal,chemical vapor deposition,encapsulation
更新于2025-09-12 10:27:22
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Hexagonal boron nitride quantum dots as a superior hole extractor for efficient charge separation in WO <sub/>3</sub> based photoelectrochemical water oxidation
摘要： Photoelectrochemical (PEC) water splitting is one of the best desirable technique to harvest clean chemical energy from abundant solar energy. However, the anodic half reaction, i.e. water oxidation is complicated due to the involvement of multiple electrons in this process. Herein, stable WO3 nanoblocks with monoclinic phase have been modified by incorporation of hexagonal boron nitride quantum dots (h-BNQDs) to improve the photogenerated electron-hole separation and additionally to hinder the charge recombination process. The photocurrent density (J) value for modified WO3 photoanode by incorporation of BNQDs has been found to be 1.63 mA/cm2 at the potential of 1.23VRHE which is approximately 2.4 fold higher than the bare WO3 photoanode. The enhancement in photocurrent density is mainly due to the hole extraction property of BNQDs on the surface of the WO3 nanoblocks. A two-fold increment in photogenerated charge carrier density (ND) value has been achieved due to better charge separation of electron-hole pairs in the modified system confirmed by the Mott-Schottky (MS) plot. Present work demonstrates a unique, low-cost strategy for enhancement of PEC water oxidation by modification of photoanode with hole extracting agents.
关键词： charge separation,boron nitride quantum dots,photoelectrochemical water oxidation,hole extracting agent,Tungsten trioxide
更新于2025-09-12 10:27:22
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Effects of Hexagonal Boron Nitride Sheets on the Optothermal Performances of Quantum Dots-Converted White LEDs
摘要： Recently, quantum dots-converted white light-emitting diodes (QDs-WLEDs) are attracting numerous attention due to their high luminous efficiency and excellent color quality. As for color conversion material, the quantum dots (QDs) are commonly embedded into a low-thermal-conductivity polymer matrix. In this case, their generated heat during the photoluminescence process can hardly be dissipated into the heat sink, leading to a high working temperature and reduced lifetime. Adding particles with high thermal conductivity to the QDs layer can enhance its thermal conductivity, and thus reduce QDs’ working temperature. At the same time, these particles may affect the optical properties of QDs. However, this problem has still not been deeply studied. In this article, we systematically investigated the effects of the highly thermal-conductive hexagonal boron nitride sheets (hBNSs) on the optothermal performances of QDs/phosphor film in white light-emitting diodes (WLEDs). The thermal conductivity of QDs/phosphor film was significantly increased by 24% after adding 5wt% of 45-μm-diameter hBNS. As for the optical performance, the transparency of the silicone gel film with 45-μm-diameter hBNS was much better than that with 6–9-μm-diameter hBNS under the same weight fraction. Furthermore, the scattering effect of hBNS plays a more important role in enhancing the light conversion performance of QDs than that of phosphor. At last, a color stability test showed the increasing rate of correlated color temperature (IRCCT) of hBNS-added WLEDs are 21% smaller than that of common WLEDs after working 153 h, meaning a better QDs stability in hBNS-added WLEDs.
关键词： light conversion,quantum dots (QDs),Hexagonal boron nitride sheets (hBNSs),thermal conductivity
更新于2025-09-11 14:15:04
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Cataluminescence coupled with photo-assisted technology: a highly efficient metal-free gas sensor for carbon monoxide
摘要： With the development of green chemistry, metal-free nano-catalysts have gradually substituted metal-based materials, causing widespread concern among researchers in many fields, especially in cataluminescence sensing, because of their long-term stability, environmental friendliness as well as low costs. Besides the catalysts, the innovations of assistant technologies for cataluminescence are needed to enhance the oxidation reactivity of the gas molecules or catalytic efficiency of sensing materials. Although, there are some groups enhancing the cataluminescence reaction via various assistant technologies, the development of assistant technologies in cataluminescence sensors are still in their infancy, the design, effect mechanism and application are still stimulating challenges. Herein, with photodynamic assistant, fluorinated nanoscale hexagonal boron nitride is first employed as a metal-free catalyst to establish a novel cataluminescence method for detecting CO gases, and the cataluminescence reaction mechanism of CO is also investigated in details. Under the best conditions, the detection limit (3σ) of the CO concentration is 0.005 μg mL-1, which has been largely improved in cataluminescence methods. The realization of detection of CO from theory to practice thorough the method of cataluminescence is beneficial of the practical application of metal-free catalysts to detect CO rather than stay at the possibility to detect CO by the means of theoretical calculation only.
关键词： metal-free gas sensor,carbon monoxide,Cataluminescence,fluorinated hexagonal boron nitride,photo-assisted technology
更新于2025-09-11 14:15:04
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Coupling of deterministically activated quantum emitters in hexagonal boron nitride to plasmonic surface lattice resonances
摘要： The cooperative phenomena stemming from the radiation field-mediated coupling between individual quantum emitters are presently attracting broad interest for applications related to on-chip photonic quantum memories and long-range entanglement. Common to these applications is the generation of electro-magnetic modes over macroscopic distances. Much research, however, is still needed before such systems can be deployed in the form of practical devices, starting with the investigation of alternate physical platforms. Quantum emitters in two-dimensional (2D) systems provide an intriguing route because these materials can be adapted to arbitrarily shaped substrates to form hybrid systems wherein emitters are near-field-coupled to suitable optical modes. Here, we report a scalable coupling method allowing color center ensembles in a van der Waals material (hexagonal boron nitride) to couple to a delocalized high-quality plasmonic surface lattice resonance. This type of architecture is promising for photonic applications, especially given the ability of the hexagonal boron nitride emitters to operate as single-photon sources at room temperature.
关键词： coupling,strain,delocalization,defect,quantum emission,photoluminescence,surface plasmons,hexagonal boron nitride,2D materials,surface lattice resonance
更新于2025-09-11 14:15:04
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Boron Nitride Nanotubes in Nanomedicine || Optical properties of boron nitride nanotubes: potential exploitation in nanomedicine
摘要： Nanotechnology is the ability and the art of exploiting nanometer-scale control on the size and the shape of a system, in order to obtain novel physicochemical properties. Chemical reactivity, optical response, and interactions with cells and tissues of nanotailored materials can be remarkably different from those of the bulk counterpart. The application of this flexibility and of the enormous potential that it brings along to the treatment, prevention, or diagnosis of diseases—that is, nanomedicine—is a novel opportunity that in spite of its young age is already representing a market valued at almost 80 billion USD in 2012 [1], with hundreds of nanomedicines and nanoformulations which are either approved or under clinical evaluation [2]. In the class of nanomaterials, boron nitride nanotubes (BNNTs) possess unique characteristics that make them particularly appealing. BNNTs are structural equivalents of carbon nanotubes (CNTs) with boron and nitrogen atoms replacing the carbon atoms of CNTs, and can be thought as a rolled sheet of hexagonal BN (h-BN) as depicted in Fig. 9.1a, b, and d. Despite their structural similarity with CNTs, they are comparable or superior to the latter in terms of several technologically relevant properties such as a thermal conductivity (at least in isotopically pure tubes) [3], thermal [4] and chemical [5] stability, piezoelectricity [6], and mechanical strength [7]. These peculiar advantages stem from the significant ionic component of the covalent bonds between B and N atoms.
关键词： Boron Nitride Nanotubes,Optical Properties,Nanotechnology,Nanomedicine
更新于2025-09-11 14:15:04
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Boron Nitride Nanotubes in Nanomedicine || Boron nitride nanotube films: preparation, properties, and implications for biology?applications
摘要： Boron nitride nanotubes (BNNTs) share the same structure as carbon nanotubes (CNTs), but have boron and nitrogen atoms sitting close to each other. Some properties of BNNTs are similar to their carbon counterparts, such as mechanical strength, thermal conductivity, and wettability. However, there are also many differences between them. BNNTs are insulators with a wide bandgap of about 6 eV, which is not sensitive to their diameter and chirality. Compared to CNTs, BNNTs are more thermally stable in air and, therefore, better candidates as fillers in metal/ceramic composites, field emitters, and thermal management materials at high temperatures. BNNTs show strong light emission at ～227 nm in the deep ultraviolet (DUV) region and are useful in optoelectronic, medical, data storage, and lithography applications. Isotopic 10BNNTs not only exhibit greatly improved thermal conductivity superior to that of CNTs, but also provide radiation shielding. Due to the electric polarization, BNNTs are piezoelectric and suitable for electromechanical devices on the nanoscale.
关键词： biology applications,Boron nitride nanotubes,properties,BNNT films,preparation
更新于2025-09-11 14:15:04
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Direct, transfer-free growth of large-area hexagonal boron nitride films by plasma-enhanced chemical film conversion (PECFC) of printable, solution-processed ammonia borane
摘要： Synthesis of large-area hexagonal boron nitride (h-BN) films for two-dimensional (2D) electronic applications typically requires high temperatures (~1000 oC) and catalytic metal substrates which necessitate transfer. Here, analogous to plasma-enhanced chemical vapor deposition, a non-thermal plasma is employed to create energetic and chemically-reactive states such as atomic hydrogen and convert a molecular precursor film to h-BN at temperatures as low as 500 oC directly on metal-free substrates – a process we term plasma-enhanced chemical film conversion (PECFC). Films containing ammonia borane as a precursor are prepared by a variety of solution processing methods including spray deposition, spin coating, and ink-jet printing, and reacted in a cold-wall reactor with a planar dielectric barrier discharge operated at atmospheric pressure in a background of argon or mixture of argon and hydrogen. Systematic characterization of the converted h-BN films by micro Raman spectroscopy shows that the minimum temperature for nucleation on silicon-based substrates can be lowered from 800 to 500 oC by the addition of a plasma. Furthermore, the crystalline domain size, as reflected by a decrease in the full-width-half-maximum, increased by more than 3 times (>40 cm-1 to ~13 cm-1). To demonstrate the potential of the h-BN films as a gate dielectric in 2D electronic devices, molybdenum disulfide field-effect transistors were fabricated and the field effect mobility was found to be improved by up to four times over silicon dioxide. Overall, PECFC allows h-BN films to be grown at lower temperatures and with improved crystallinity than CVD, directly on substrates suitable for electronic device fabrication.
关键词： two-dimensional (2D) material,plasma,chemical vapor deposition (CVD),boron nitride (BN)
更新于2025-09-11 14:15:04
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Wafer-scale single-crystal hexagonal boron nitride film via self-collimated grain formation
摘要： Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide.
关键词： single-crystalline,hexagonal boron nitride,wafer-scale,tungsten disulfide,chemical vapor deposition,graphene/hBN heterostructure
更新于2025-09-10 09:29:36
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Angular Optical Transparency Induced by Photonic Topological Transition in Hexagonal Boron Nitride
摘要： The transmission property of hexagonal boron nitride at its four photonic topological transitions has been studied. An interesting result is revealed that the angular optical transparency can be achieved at wavelength 12.0494 μm. The numerical results indicate that the transparency window has an angular full width at half maximum of 4° with an optical transmission higher than 0.9 at normal incidence. Besides, corresponding to an angular full width at half maximum narrower than 20°, the wavelength span is about 230 nm. These features may make the hexagonal boron nitride holds promise for applications in private screens and optical detectors.
关键词： Hexagonal boron nitride,Photonic topological transition,Angular transparency
更新于2025-09-10 09:29:36