The Experts below are selected from a list of 27594 Experts worldwide ranked by ideXlab platform
Xiaoqing Jiang - One of the best experts on this subject based on the ideXlab platform.
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production of mono to few layer mos2 nanosheets in isopropanol by a salt assisted direct liquid phase Exfoliation method
Journal of Colloid and Interface Science, 2018Co-Authors: Huaizhi Liu, Yinyan Zhu, Weixu Liu, Bo Zhou, Lihua Zhu, Xiaoqing JiangAbstract:Abstract Here, we report a facile salt-assisted direct liquid-phase Exfoliation method for mass production of MoS2 nanosheets. We choose organic solvent isopropanol (IPA) as Exfoliation media and potassium ferrocyanide, potassium sodium tartrate, or sodium tartrate as salt, the assistant. The selected salts show universal and efficient assistant effect for the Exfoliation of MoS2 in IPA. Especially, potassium ferrocyanide (K4Fe(CN)6) can enhance the Exfoliation efficiency up to 73 times and a dispersion of MoS2 nanosheets with concentration as high as 0.240 mg mL−1 can be easily obtained in IPA-K4Fe(CN)6 system. Transmission electron microscopy, atomic force microscopy (AFM), and Raman spectroscopy show that bulk MoS2 has been successfully exfoliated into mono- to few-layer MoS2 nanosheets. AFM analysis indicates that nearly 60% flakes are monolayer in MoS2 dispersion.
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from graphite to graphene direct liquid phase Exfoliation of graphite to produce single and few layered pristine graphene
Journal of Materials Chemistry, 2013Co-Authors: Xiaoqing Jiang, Lihua ZhuAbstract:Graphene, a two-dimensional crystalline form of carbon, has attracted wide and intense interest owing to its excellent physical properties and because its surface and edges can be chemically modified readily. Development of a method for producing high-quality graphene in large quantities is essential for further investigation of its properties and applications. The direct liquid-phase Exfoliation of graphite to produce graphene is a convenient method for generating ideal graphene samples in large quantities. This direct method, which involves the use of colloidal suspensions, is based on the one-step physical transformation of graphite into graphene and has many unique advantages. A large number of liquids have been employed as Exfoliation media and show a range of Exfoliation efficiencies. In this review, we highlight the recent progress made on the Exfoliation of bulky graphite powders or flakes into single- and few-layered graphene sheets in various liquids, including organic solvents, ionic liquids, and water/surfactant solutions. The qualities and yields of the exfoliated graphene samples, as well as their use in various applications, are also reviewed. Furthermore, future research directions for the development of novel Exfoliation media and more efficient techniques for producing well-exfoliated pristine graphene are proposed.
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organic salt assisted liquid phase Exfoliation of graphite to produce high quality graphene
Chemical Physics Letters, 2013Co-Authors: Peipei Sun, Yinyan Zhu, Xiaoqing JiangAbstract:Abstract Certain ordinary organic salts, such as edetate disodium, sodium tartrate, potassium sodium tartrate and sodium citrate were found to have universal and efficient assistant effect for liquid-phase Exfoliation of graphite in common organic solvents to produce pristine graphene. Up to 123 times enhanced Exfoliation efficiency was observed when sodium citrate was introduced into an Exfoliation system consisting of natural graphite powder and dimethyl sulfoxide. TEM, AFM, Raman spectroscopy, EDX, TGA, and FTIR analysis showed graphite was successfully exfoliated into single or few-layer graphene nanosheets which were free of defects and oxides. The method is simple, effective, safe and economical.
Huiming Cheng - One of the best experts on this subject based on the ideXlab platform.
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simultaneous production and functionalization of boron nitride nanosheets by sugar assisted mechanochemical Exfoliation
Advanced Materials, 2019Co-Authors: Shaohua Chen, Huiming Cheng, Jiaman Liu, Xiaolong Zou, Ling Qiu, Feiyu Kang, Bilu LiuAbstract:Due to their extraordinary properties, boron nitride nanosheets (BNNSs) have great promise for many applications. However, the difficulty of their efficient preparation and their poor dispersibility in liquids are the current factors that limit this. A simple yet efficient sugar-assisted mechanochemical Exfoliation (SAMCE) method is developed here to simultaneously achieve their Exfoliation and functionalization. This method has a high actual Exfoliation yield of 87.3%, and the resultant BNNSs are covalently grafted with sugar (sucrose) molecules, and are well dispersed in both water and organic liquids. A new mechanical force-induced Exfoliation and chemical grafting mechanism is proposed based on experimental and density functional theory investigations. Thanks to the good dispersibility of the nanosheets, flexible and transparent BNNS/poly(vinyl alcohol) (PVA) composite films with multifunctionality is fabricated. Compared to pure PVA films, the composite films have a remarkably improved tensile strength and thermal dissipation capability. Noteworthy, they are flame retardant and can effectively block light from the deep blue to the UV region. This SAMCE production method has proven to be highly efficient, green, low cost, and scalable, and is extended to the Exfoliation and functionalization of other two-dimensional (2D) materials including MoS2 , WS2 , and graphite.
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synthesis of graphene sheets with high electrical conductivity and good thermal stability by hydrogen arc discharge Exfoliation
ACS Nano, 2009Co-Authors: Zhongshuai Wu, Jinping Zhao, Zongping Chen, Daiming Tang, Bing Yu, Chuanbin Jiang, Huiming ChengAbstract:We developed a hydrogen arc discharge Exfoliation method for the synthesis of graphene sheets (GSs) with excellent electrical conductivity and good thermal stability from graphite oxide (GO), in combination with solution-phase dispersion and centrifugation techniques. It was found that efficient Exfoliation and considerable deoxygenation of GO, and defect elimination and healing of exfoliated graphite can be simultaneously achieved during the hydrogen arc discharge Exfoliation process. The GSs obtained by hydrogen arc discharge Exfoliation exhibit a high electrical conductivity of210 3 S/cm and high thermal stability with oxidization resistance temperature of 601 °C, which are much better than those prepared by argon arc discharge Exfoliation (2 10 2 S/cm, 525 °C) and by conventional thermal Exfoliation (80 S/cm, 507 °C) with the same startingGO.TheseresultsdemonstratethatthishydrogenarcdischargeExfoliationmethodisagoodapproachfor the preparation of GSs with a good quality.
Paolo Samori - One of the best experts on this subject based on the ideXlab platform.
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supramolecular approaches to graphene from self assembly to molecule assisted liquid phase Exfoliation
Advanced Materials, 2016Co-Authors: Artur Ciesielski, Paolo SamoriAbstract:Graphene, a one-atom thick two-dimensional (2D) material, is at the core of an ever-growing research effort due to its combination of unique mechanical, thermal, optical and electrical properties. Two strategies are being pursued for the graphene production: the bottom-up and the top-down. The former relies on the use of covalent chemistry approaches on properly designed molecular building blocks undergoing chemical reaction to form 2D covalent networks. The latter occurs via Exfoliation of bulk graphite into individual graphene sheets. Amongst the various types of Exfoliations exploited so far, ultrasound-induced liquid-phase Exfoliation (UILPE) is an attractive strategy, being extremely versatile, up-scalable and applicable to a variety of environments. In this review, we highlight the recent developments that have led to successful non-covalent functionalization of graphene and how the latter can be exploited to promote the process of molecule-assisted UILPE of graphite. The functionalization of graphene with non-covalently interacting molecules, both in dispersions as well as in dry films, represents a promising and modular approach to tune various physical and chemical properties of graphene, eventually conferring to such a 2D system a multifunctional nature.
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organic radical assisted electrochemical Exfoliation for the scalable production of high quality graphene
Journal of the American Chemical Society, 2015Co-Authors: Sheng Yang, Zhongshuai Wu, Paolo Samori, Sebastian Bruller, Khaled Parvez, Renhao Dong, Fanny Richard, Xinliang Feng, Klaus MullenAbstract:Despite the intensive research efforts devoted to graphene fabrication over the past decade, the production of high-quality graphene on a large scale, at an affordable cost, and in a reproducible manner still represents a great challenge. Here, we report a novel method based on the controlled electrochemical Exfoliation of graphite in aqueous ammonium sulfate electrolyte to produce graphene in large quantities and with outstanding quality. Because the radicals (e.g., HO•) generated from water electrolysis are responsible for defect formation on graphene during electrochemical Exfoliation, a series of reducing agents as additives (e.g., (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), ascorbic acid, and sodium borohydride) have been investigated to eliminate these radicals and thus control the Exfoliation process. Remarkably, TEMPO-assisted Exfoliation results in large graphene sheets (5–10 μm on average), which exhibit outstanding hole mobilities (∼405 cm2 V–1 s–1), very low Raman ID/IG ratios (below 0.1)...
Yinyan Zhu - One of the best experts on this subject based on the ideXlab platform.
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production of mono to few layer mos2 nanosheets in isopropanol by a salt assisted direct liquid phase Exfoliation method
Journal of Colloid and Interface Science, 2018Co-Authors: Huaizhi Liu, Yinyan Zhu, Weixu Liu, Bo Zhou, Lihua Zhu, Xiaoqing JiangAbstract:Abstract Here, we report a facile salt-assisted direct liquid-phase Exfoliation method for mass production of MoS2 nanosheets. We choose organic solvent isopropanol (IPA) as Exfoliation media and potassium ferrocyanide, potassium sodium tartrate, or sodium tartrate as salt, the assistant. The selected salts show universal and efficient assistant effect for the Exfoliation of MoS2 in IPA. Especially, potassium ferrocyanide (K4Fe(CN)6) can enhance the Exfoliation efficiency up to 73 times and a dispersion of MoS2 nanosheets with concentration as high as 0.240 mg mL−1 can be easily obtained in IPA-K4Fe(CN)6 system. Transmission electron microscopy, atomic force microscopy (AFM), and Raman spectroscopy show that bulk MoS2 has been successfully exfoliated into mono- to few-layer MoS2 nanosheets. AFM analysis indicates that nearly 60% flakes are monolayer in MoS2 dispersion.
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organic salt assisted liquid phase Exfoliation of graphite to produce high quality graphene
Chemical Physics Letters, 2013Co-Authors: Peipei Sun, Yinyan Zhu, Xiaoqing JiangAbstract:Abstract Certain ordinary organic salts, such as edetate disodium, sodium tartrate, potassium sodium tartrate and sodium citrate were found to have universal and efficient assistant effect for liquid-phase Exfoliation of graphite in common organic solvents to produce pristine graphene. Up to 123 times enhanced Exfoliation efficiency was observed when sodium citrate was introduced into an Exfoliation system consisting of natural graphite powder and dimethyl sulfoxide. TEM, AFM, Raman spectroscopy, EDX, TGA, and FTIR analysis showed graphite was successfully exfoliated into single or few-layer graphene nanosheets which were free of defects and oxides. The method is simple, effective, safe and economical.
Seong-ju Hwang - One of the best experts on this subject based on the ideXlab platform.
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organic intercalant free liquid Exfoliation route to layered metal oxide nanosheets via the control of electrostatic interlayer interaction
ACS Applied Materials & Interfaces, 2019Co-Authors: Jang Mee Lee, Bohyun Kang, Seong-ju HwangAbstract:A scalable organic intercalant-free liquid Exfoliation route to 2D nanosheets (NSs) of layered transition-metal oxides (TMOs) is developed by employing hydronium-intercalated derivatives as precursors. The replacement of interlayer alkali metal ions with larger hydronium ions via acid treatment makes possible the efficient liquid Exfoliation of TMOs without any assistance of organic intercalant cations. Not only a weakening of interlayer electrostatic interaction upon hydronium intercalation but also an efficient solvation of deintercalated hydronium ions via hydrogen bonding with polar solvents is mainly responsible for the high efficacy of hydronium-intercalated TMOs as precursors for liquid Exfoliation. The nature of the solvent employed also has a profound effect on the Exfoliation yield of these TMO NSs; viscosity, surface tension, density, and Hansen solubility parameter as well as the capability to solvate the exfoliated NSs and hydronium ions are crucial factors for determining the Exfoliation efficiency of the hydronium-intercalated precursor. All the obtained Ti1- xO2, MnO2, and RuO2 NSs show highly anisotropic 2D morphologies and distinct negative surface charges with a zeta potential of -30 to -50 mV. Such distinct surface charges of these NSs render them versatile hybridization matrices for the synthesis of novel nanohybrids with enhanced functionalities. The hybridization with the liquid-exfoliated TMO NSs is quite effective in improving the photocatalytic activity of CdS and the electrode functionalities of graphene and graphene-layered double hydroxide nanohybrids. The present study underscores the usefulness of the present liquid Exfoliation method in synthesizing organic-free TMO NSs and their nanohybrids as well as in widening the application field of exfoliated TMO NSs.
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Organic Intercalant-Free Liquid Exfoliation Route to Layered Metal-Oxide Nanosheets via the Control of Electrostatic Interlayer Interaction
2019Co-Authors: Jang Mee Lee, Bohyun Kang, Seong-ju HwangAbstract:A scalable organic intercalant-free liquid Exfoliation route to 2D nanosheets (NSs) of layered transition-metal oxides (TMOs) is developed by employing hydronium-intercalated derivatives as precursors. The replacement of interlayer alkali metal ions with larger hydronium ions via acid treatment makes possible the efficient liquid Exfoliation of TMOs without any assistance of organic intercalant cations. Not only a weakening of interlayer electrostatic interaction upon hydronium intercalation but also an efficient solvation of deintercalated hydronium ions via hydrogen bonding with polar solvents is mainly responsible for the high efficacy of hydronium-intercalated TMOs as precursors for liquid Exfoliation. The nature of the solvent employed also has a profound effect on the Exfoliation yield of these TMO NSs; viscosity, surface tension, density, and Hansen solubility parameter as well as the capability to solvate the exfoliated NSs and hydronium ions are crucial factors for determining the Exfoliation efficiency of the hydronium-intercalated precursor. All the obtained Ti1–xO2, MnO2, and RuO2 NSs show highly anisotropic 2D morphologies and distinct negative surface charges with a zeta potential of −30 to −50 mV. Such distinct surface charges of these NSs render them versatile hybridization matrices for the synthesis of novel nanohybrids with enhanced functionalities. The hybridization with the liquid-exfoliated TMO NSs is quite effective in improving the photocatalytic activity of CdS and the electrode functionalities of graphene and graphene-layered double hydroxide nanohybrids. The present study underscores the usefulness of the present liquid Exfoliation method in synthesizing organic-free TMO NSs and their nanohybrids as well as in widening the application field of exfoliated TMO NSs
