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Direct Liquid Phase Exfoliation of Graphite to Produce Few-Layer Graphene by Microfluidization
摘要： Graphene has attracted a great number of attentions due to the excellent physical and chemical properties. For the convenience of investigations and applications, it is crucial to produce the grapheme with high-quality and high-yield by an easy-obtained method. In this research, a promising method is demonstrated to produce a high-concentration few-layer graphene (FLG) dispersion by direct micro?uidization in water/surfactant systems. The effects of surfactant selection, chamber pressure and micro?uidization cycles on the graphitic material exfoliation ef?ciency are systematically studied. The FLG concentration and the quality of the as-prepared FLG were determined by a series of characterizations. The graphene dispersions, with an average lateral size of 0.6 (cid:2)m and a few-layer structure, were stabilized by surfactants at a high concentration of up to 1.7 mg/mL and = 0.07–0.56, C/O ～ 19(cid:3)36) within a processing time of a few hours. This method should facilitate the mass production of high-quality graphene by liquid-phase exfoliation and promote the industrial application of graphene.
关键词： High Concentration,Few-Layer Graphene,Micro?uidization,Liquid Phase Exfoliation,Aqueous Graphene Dispersion
更新于2025-09-09 09:28:46
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Hydrothermal assembly of one-dimensional boron nitride nanostructures
摘要： Boron nitride (BN) is a state-of-the-art ultrawide bandgap semiconducting material. One-dimensional (1D) boron nitride nanostructures have high thermal conductivity (~600 W/mK) and wide band gap (5~6eV), which make it a promising thermal interface material. The 1D BN nanostructures were usually synthesized with chemical vapor deposition, restricted by the low yield and the high cost. Herein, we present a facile hydrothermal method to get 1D BN nanostructures. In the hydrothermal process, 2D BN nanosheets were firstly exfoliated from the BN powder, and then curled into 1D BN nanostructure through the chemical etching with sodium hydroxide. The alternative approach exhibited a high yield and a high concentration, which should be meaningful for the fabrication of 1D BN nanostructures.
关键词： One-dimensional nanostructure,Hydrothermal exfoliation,Chemical etching,Boron nitride
更新于2025-09-04 15:30:14
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Universality of strain-induced anisotropic friction domains on 2D materials
摘要： Van der Waals two-dimensional (2D) materials have shown various physical characteristics depending on their growth methods and conditions. Among those characteristics, the surface structural properties are crucial for the application of 2D materials, as the surface structures readily affect their atomic arrangements and/or interaction with substrates due to their atomic-scale thicknesses. Here, we report on the anisotropic friction domains of MoS2 grown not only by chemical vapor deposition (CVD) under various sulfur pressure conditions but also by a mechanical exfoliation process. The 180° periodicity of each domain and the 60° shift between adjacent domains indicate the presence of linearly aligned structures along the armchair direction of MoS2, which is determined by the optical second-harmonic generation method. The anisotropic friction domains of CVD-grown MoS2 ?akes may be attributed to linearly aligned ripples caused by an inhomogeneous strain ?eld distribution, which is due, in turn, to randomly formed nucleation sites on the substrate. The universality of the anisotropic frictional behaviors of 2D materials, including graphene, hBN, and WS2 with honeycomb lattice stacking, which differ from ReSe2 with a distorted triclinic 1T’ structure, supports our assumption based on the linearly aligned ripples along the crystallographic axes, which result from an inhomogeneous strain ?eld.
关键词： strain-induced ripples,chemical vapor deposition,mechanical exfoliation,anisotropic friction domains,Van der Waals two-dimensional materials
更新于2025-09-04 15:30:14
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Pseudoexfoliation material on posterior chamber intraocular lenses
摘要： The presence of pseudoexfoliation material on the surface of an intraocular lens (IOL) is a rare finding. We report a series of seven cases with different patterns of pseudoexfoliation material deposition on the posterior chamber IOLs, recognized 2–20 years after cataract surgery. Six patients had an IOL implanted in the capsular bag and one in the ciliary sulcus. Two patients had undergone posterior capsulotomy. Although the pathophysiological mechanisms and clinical significance of this finding remain unknown, the careful follow-up of pseudophakic patients with known or suspected pseudoexfoliation syndrome is essential to monitor the development or progression of glaucoma, since deposition of pseudoexfoliation material continues even after cataract surgery.
关键词： cataract,intraocular lens,exfoliation syndrome,glaucoma
更新于2025-09-04 15:30:14
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Atomically Thin 2D‐Arsenene by Liquid‐Phased Exfoliation: Toward Selective Vapor Sensing
摘要： Phosphorene and antimonene, single- or few-layered (FL) semiconductor materials, have recently attracted enormous attention due to their unique properties, provided by their extreme thinness. Here, a liquid-phase exfoliation (LPE) procedure to prepare FL arsenene, another member of pnictogens, assisted by sonication and without any additional surfactant is reported. The exfoliation process is performed in various solvents. Among those, N-methylpyrrolidone is found to provide the highest concentration of stable arsenene sheets. Spectroscopic and microscopic analyses confirm the formation of high-quality few-layer arsenene nanosheets with large lateral dimensions. An application of this material for construction of vapor sensor based on electrochemical impedance spectroscopy is demonstrated. The device detects selectively methanol or acetone vapors depending on the selected resonance frequency. The results are highly reproducible, and the vapor sensor has long-term stability.
关键词： centrifugation,arsenic,2D arsenene,vapor sensors,liquid-phase exfoliation
更新于2025-09-04 15:30:14
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Solution Processing for Lateral Transition Metal Dichalcogenides Homojunction from Polymorphic Crystal
摘要： Homojunctions comprised of transition metal dichalcogenides (TMD) polymorphs are attractive building blocks for next-generation two-dimensional (2D) electronic circuitry. However, the synthesis of such homojunctions, which usually involves elaborate manipulation at nanoscale, still remains a great challenge. Herein, we demonstrated a solution-processing strategy to successfully harvest lateral semiconductor-metal homojunctions with high yield. Specially, through precisely controlled lithiation process, precursors of polymorphic crystal arranged with 1T-2H domains were successfully achieved. A programmed exfoliation procedure was further employed to orderly laminate each phase in the polymorphic crystal, thus leading to 1T-2H TMD homojunction monolayers with size up to tens of micrometers. Moreover, the atomically sharp boundaries and superior band alignment improved the device based on the semiconductor-metal homojunction with 50% decrease of electric field strength required in the derivation of state transition. We anticipate that solution processing based on programmed exfoliation would be a powerful tool to produce new configurations of 2D nanomaterials.
关键词： homojunctions,polymorphic crystal,transition metal dichalcogenides,programmed exfoliation,solution processing
更新于2025-09-04 15:30:14
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The Post Annealing to Control the Number of Layers of 2D MoS2 and SnS2
摘要： We have demonstrated that post annealing could control the layer thickness of 2D MoS2 and SnS2 films transferred on a SiO2/Si substrate by varying the annealing temperature and time. Atomic force microscopy and Raman spectroscopy characterizations revealed that higher annealing temperature and longer treatment time led to thinner films, lower residues and fewer impurities on the surface of 2D materials. In addition, a higher possibility to attain few-layers on both 2D films was achieved using post annealing. The multiple layers of pristine films having the thickness over 15 nm were reduced down to bi-layers after annealing. We observed that the moderate annealing temperature of 450 °C on led to effective layer-thinning compared to the films annealed at 340 °C. The post annealing at 450 °C produced very smooth few-layers (≤4 nm thickness, >1 μm size) of 2D MoS2 and SnS2. However, the 2D films decomposed or disappeared at temperature greater than 650 °C. In addition, process time also affected the number of layers and the sweet spot turned out to be 2 to 3 hours in our experiment.
关键词： Annealing,Mechanical Exfoliation,Layer-Thinning,2D Materials,SnS2,MoS2
更新于2025-09-04 15:30:14