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1.
Ultrathin two‐dimensional nanosheets have been widely studied because of their peculiar properties and promising applications. As a typical layered material, successful exfoliation of freestanding ultrathin lepidocrocite (γ‐FeOOH) nanosheets from the bulk material has not been reported to date. Herein, we report a facile synthetic route to prepare ultrathin lepidocrocite nanosheets with a thickness of approximately 2–3 nm from FeOx–propanediol layered precursors through weakening of the hydrogen bonds during the crystallization process. The ultrathin morphology and single‐crystal structure of the nanosheets were confirmed by transmission electron microscopy, X‐ray diffraction, and atomic force microscopy. The formation process of these nanosheets demonstrated simultaneous exfoliation and crystallization of lepidocrocite in basic aqueous solution. The obtained ultrathin nanosheets exhibited a much lower Néel temperature (18.3 K) than bulk lepidocrocite and weak ferromagnetic behavior below this temperature. 相似文献
2.
Dr. Albert S. Nazarov Dr. Viktor N. Demin Ekaterina D. Grayfer Dr. Alexander I. Bulavchenko Dr. Aida T. Arymbaeva Dr. Hyeon‐Jin Shin Dr. Jae‐Young Choi Prof. Dr. Vladimir E. Fedorov 《化学:亚洲杂志》2012,7(3):554-560
A mixture of bulk hexagonal boron nitride (h‐BN) with hydrazine, 30 % H2O2, HNO3/H2SO4, or oleum was heated in an autoclave at 100 °C to produce functionalized h‐BN. The product formed stable colloid solutions in water (0.26–0.32 g L ?1) and N,N‐dimethylformamide (0.34–0.52 g L ?1) upon mild ultrasonication. The yield of “soluble” h‐BN reached about 70 wt %. The dispersions contained few‐layered h‐BN nanosheets with lateral dimensions in the order of several hundred nanometers. The functionalized dispersible h‐BN was characterized by IR spectroscopy, X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV/Vis spectroscopy, X‐ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). It is shown that h‐BN preserves its hexagonal structure throughout the functionalization procedure. Its exfoliation into thin platelets upon contact with solvents is probably owing to the attachment of hydrophilic functionalities. 相似文献
3.
Dr. Wenshuai Zhu Dr. Xiang Gao Dr. Qian Li Dr. Hongping Li Dr. Yanhong Chao Dr. Meijun Li Dr. Shannon M. Mahurin Prof. Huaming Li Dr. Huiyuan Zhu Prof. Sheng Dai 《Angewandte Chemie (International ed. in English)》2016,55(36):10766-10770
The controlled exfoliation of hexagonal boron nitride (h‐BN) into single‐ or few‐layered nanosheets remains a grand challenge and becomes the bottleneck to essential studies and applications of h‐BN. Here, we present an efficient strategy for the scalable synthesis of few‐layered h‐BN nanosheets (BNNS) using a novel gas exfoliation of bulk h‐BN in liquid N2 (L‐N2). The essence of this strategy lies in the combination of a high temperature triggered expansion of bulk h‐BN and the cryogenic L ‐N2 gasification to exfoliate the h‐BN. The produced BNNS after ten cycles (BNNS‐10) consisted primarily of fewer than five atomic layers with a high mass yield of 16–20 %. N2 sorption and desorption isotherms show that the BNNS‐10 exhibited a much higher specific surface area of 278 m2 g?1 than that of bulk BN (10 m2 g?1). Through the investigation of the exfoliated intermediates combined with a theoretical calculation, we found that the huge temperature variation initiates the expansion and curling of the bulk h‐BN. Subseqently, the L ‐N2 penetrates into the interlayers of h‐BN along the curling edge, followed by an immediate drastic gasification of L ‐N2, further peeling off h‐BN. This novel gas exfoliation of high surface area BNNS not only opens up potential opportunities for wide applications, but also can be extended to produce other layered materials in high yields. 相似文献
4.
Carlos Gibaja David Rodriguez‐San‐Miguel Pablo Ares Prof. Julio Gómez‐Herrero Dr. Maria Varela Dr. Roland Gillen Prof. Janina Maultzsch Dr. Frank Hauke Prof. Andreas Hirsch Dr. Gonzalo Abellán Dr. Félix Zamora 《Angewandte Chemie (International ed. in English)》2016,55(46):14345-14349
We report on a fast and simple method to produce highly stable isopropanol/water (4:1) suspensions of few‐layer antimonene by liquid‐phase exfoliation of antimony crystals in a process that is assisted by sonication but does not require the addition of any surfactant. This straightforward method generates dispersions of few‐layer antimonene suitable for on‐surface isolation. Analysis by atomic force microscopy, scanning transmission electron microscopy, and electron energy loss spectroscopy confirmed the formation of high‐quality few‐layer antimonene nanosheets with large lateral dimensions. These nanolayers are extremely stable under ambient conditions. Their Raman signals are strongly thickness‐dependent, which was rationalized by means of density functional theory calculations. 相似文献
5.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(35):10579-10581
Among 2D materials that recently have attracted enormous interest, black phosphorus (BP) is gaining a rising popularity due to its tunable band‐gap structure, which is strongly correlated to the thickness and can enable its use in optoelectronic and electronic applications. It is therefore important to provide a facile and scalable methodology to prepare single or few‐layer BP nanosheets. We propose herein a simple and fast top‐down method to exfoliate a BP crystal into nanosheets of reduced thickness by using electrochemistry. The application of an anodic potential to the crystal in an acidic aqueous solution allows control over the exfoliation efficiency and quality of the nanosheets produced. X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and scanning transmission electron microscopy (STEM) have been applied to fully characterize the exfoliated material, which presented significantly reduced layer thickness compared to the starting bulk material. 相似文献
6.
类石墨烯二硫化钼及其在光电子器件上的应用 总被引:4,自引:0,他引:4
由单层或几层二硫化钼构成的类石墨烯二硫化钼(graphene-like MoS2)是一种具有类似石墨烯结构和性能的新型二维(2D)层状化合物, 近年来以其独特的物理、化学性质而成为新兴的研究热点. 本文综述了近年来类石墨烯二硫化钼常见的几种制备方法, 包括以微机械力剥离、锂离子插层和液相超声法等为主的“自上而下”的剥离法, 以及以高温热分解、水热法等为主的“自下而上”的合成法; 介绍了其常用的结构表征方法, 包括原子力显微镜(AFM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和拉曼光谱等; 概述了类石墨烯二硫化钼的紫外-可见(UV-Vis)吸收、荧光发射等基本光物理性质及其相关机理; 总结了类石墨烯二硫化钼在二次电池、场效应晶体管、传感器、有机电致发光二极管和电存储等光电子器件领域的应用原理及其研究进展, 展望了这类新型二维层状化合物的研究前景. 相似文献
7.
Kun'ichi Miyazawa Takuro Nagai Koji Kimoto Masaru Yoshitake Yumi Tanaka 《Surface and interface analysis : SIA》2021,53(1):84-89
We analyzed the surface atomic structure of highly oriented pyrolytic graphite (HOPG) substrate exfoliated with adhesive tape, using high‐resolution transmission electron microscopy and scanning transmission electron microscopy‐electron energy‐loss spectroscopy (STEM‐EELS). The surface step height of the exfoliated HOPG substrate was determined using high‐angle annular dark‐field‐scanning transmission electron microscopy (HAADF‐STEM) images and the depth profiles of the EELS spectra of a cross‐sectioned thin foil specimen prepared via focused ion beam milling. The exfoliated surface of the HOPG substrate presented disordered and curved graphene layers. The STEM‐EELS measurements indicated that upon exfoliation, the surface of the HOPG substrate reacted with atmospheric water and oxygen molecules. 相似文献
8.
In this study, the immobilization of sulfonic acid on silica‐layered magnetite was carried out by the reaction of ClSO3H with silica‐layered magnetite. The prepared magnetic nanoparticles of Fe3O4@SiO2‐SO3H were then characterized using scanning electron microscopy, energy dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and transmission electron microscopy. The sulfonated nanocomposite exhibited excellent catalytic activity and reusability in the reduction of various aldoximes and ketoximes with NaBH3CN in the presence of ZrCl4. All reactions were carried out under solvent‐free conditions (r.t. or 75–80°C) within 3–70 min to afford amines in high to excellent yields. 相似文献
9.
Anchoring Ni (II) on Fe3O4@tryptophan: A recyclable,green and extremely efficient magnetic nanocatalyst for one‐pot synthesis of 5‐substituted 1H‐tetrazoles and chemoselective oxidation of sulfides and thiols 下载免费PDF全文
Nazanin Moeini Taiebeh Tamoradi Mohammad Ghadermazi Arash Ghorbani‐Choghamarani 《应用有机金属化学》2018,32(9)
A green, novel and extremely efficient nanocatalyst was successfully synthesized by the immobilization of Ni as a transition metal on Fe3O4 nanoparticles coated with tryptophan. This nanostructured material was characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, thermogravimetric analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometry and X‐ray diffraction. The prepared nanocatalyst was applied for the oxidation of sulfides, oxidative coupling of thiols and synthesis of 5‐substituted 1H‐tetrazoles. The use of non‐toxic, green and inexpensive materials, easy separation of magnetic nanoparticles from a reaction mixture using a magnetic field, efficient and one‐pot synthesis, and high yields of products are the most important advantages of this nanocatalyst. 相似文献
10.
Yong Chae Jung Jin Hee Kim Takuya Hayashi Yoong Ahm Kim Morinobu Endo Mauricio Terrones Mildred S. Dresselhaus 《Macromolecular rapid communications》2012,33(8):628-634
We report a mechanically strong, electrically and thermally conductive, and optically transparent shape‐memory polyurethane composite which was fabricated by introducing a small amount (0.1 wt%) of high‐quality graphene as a filler. Geometrically large (≈4.6 μm2), but highly crystallized few‐layer graphenes, verified by Raman spectroscopy and transmission electron microscopy, were prepared by the sonication of expandable graphite in an organic solvent. Oxygen‐ containing functional groups at the edge plane of graphene were crucial for an effective stress transfer from the graphene to polyurethane. Homogeneously dispersed few‐layered graphene enabled polyurethane to have a high shape recovery force of 1.8 MPa cm−3. Graphene, which is intrinsically stretchable up to 10%, will enable high‐performance composites to be fabricated at relatively low cost and we thus envisage that such composites may replace carbon nanotubes for various applications in the near future. 相似文献
11.
Ying‐Ming Zhang Yong Chen Dr. Yang Yang Peng Liu Yu Liu Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(42):11333-11340
The Hirsch–Bingel reaction of bis{4‐methyl[1,2,3]triazolyl}malonic ester‐bridged bis(permethyl‐β‐cyclodextrin) 1 with C60 has led to the formation of a new fullerene‐bridged bis(permethyl‐β‐cyclodextrin) 2 , which has been comprehensively characterized by NMR spectroscopy, MALDI‐MS, and elemental analysis. Taking advantage of the high affinity between 2 and 5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphyrin ( 3 ) or [5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphinato]zinc(II) ( 4 ), linear supramolecular architectures with a width of about 2 nm and a length ranging from hundreds of nanometers to micron dimension were conveniently constructed and fully investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Significantly, the photoinduced electron‐transfer (PET) process between porphyrin and C60 moieties takes place within the 2 ? 3 and 2 ? 4 supramolecular architectures under light irradiation, leading to the highly efficient quenching of the porphyrin fluorescence. The PET process and the charge‐separated state were investigated by means of fluorescence spectroscopy, fluorescence decay, cyclic voltammetry, and nanosecond transient absorption measurements. 相似文献
12.
Biwei Xiao Hanshuo Liu Ning Chen Mohammad Norouzi Banis Haijun Yu Jianwen Liang Qian Sun Tsun‐Kong Sham Ruying Li Mei Cai Gianluigi A. Botton Xueliang Sun 《Angewandte Chemie (International ed. in English)》2020,59(34):14313-14320
Li‐ and Mn‐rich layered oxides are among the most promising cathode materials for Li‐ion batteries with high theoretical energy density. Its practical application is, however, hampered by the capacity and voltage fade after long cycling. Herein, a finite difference method for near‐edge structure (FDMNES) code was combined with in situ X‐ray absorption spectroscopy (XAS) and transmission electron microscopy/electron energy loss spectroscopy (TEM/EELS) to investigate the evolution of transition metals (TMs) in fresh and heavily cycled electrodes. Theoretical modeling reveals a recurring partially reversible LiMn2O4‐like sub‐nanodomain formation/dissolution process during each charge/discharge, which accumulates gradually and accounts for the Mn phase transition. From the modeling of spectra and maps of the valence state over large regions of the cathodes, it was found that the phase change is size‐dependent. After prolonged cycling, the TMs displayed different levels of inactivity. 相似文献
13.
A Delamination Strategy for Thinly Layered Defect‐Free High‐Mobility Black Phosphorus Flakes 下载免费PDF全文
Sheng Yang Ke Zhang Antonio Gaetano Ricciardulli Panpan Zhang Dr. Zhongquan Liao Dr. Martin R. Lohe Prof. Ehrenfried Zschech Prof. Paul W. M. Blom Prof. Wojciech Pisula Prof. Klaus Müllen Prof. Xinliang Feng 《Angewandte Chemie (International ed. in English)》2018,57(17):4677-4681
Extraordinary electronic and photonic features render black phosphorus (BP) an important material for the development of novel electronics and optoelectronics. Despite recent progress in the preparation of thinly layered BP flakes, scalable synthesis of large‐size, pristine BP flakes remains a major challenge. An electrochemical delamination strategy is demonstrated that involves intercalation of diverse cations in non‐aqueous electrolytes, thereby peeling off bulk BP crystals into defect‐free flakes comprising only a few layers. The interplay between tetra‐n‐butylammonium cations and bisulfate anions promotes a high exfoliation yield up to 78 % and large BP flakes up to 20.6 μm. Bottom‐gate and bottom‐contact field‐effect transistors, comprising single BP flakes only a few layers thick, exhibit a high hole mobility of 252±18 cm2 V?1 s?1 and a remarkable on/off ratio of (1.2±0.15)×105 at 143 K under vacuum. This efficient and scalable delamination method holds great promise for development of BP‐based composites and optoelectronic devices. 相似文献
14.
Riccardo Salvio Sven Krabbenborg Wouter J. M. Naber Aldrik H. Velders David N. Reinhoudt Wilfred G. van der Wiel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(33):8235-8240
The treatment of a suspension of graphite oxide (GO) with sodium azide leads to a material that, after reduction, features amino groups at the top and bottom of the sheets. These groups react through microcontact printing with an isothiocyanate monolayer on a silicon oxide substrate to form covalent bonds that strongly attach to the particles on the surface. With ultrasonication it is possible to obtain exfoliation of the sheets that are not covalently bound to the surface leaving single‐layer platelets attached to the substrate. The azido derivative can be also used to functionalize the graphene oxide with long alkylic chains through a click chemistry approach. This functionalization results in the exfoliation of this material in dimethylformamide. The novel materials were fully characterized by different techniques including IR spectroscopy, thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM and TEM), X‐Ray photoelectron spectroscopy (XPS), and solid state NMR spectroscopy. The material with amino groups, after the reduction step, is conductive with a resistivity only approximately seven times larger than that of unprocessed graphite. This implies that after reduction of the GO, the conjugated sp2 network is largely restored. We consider this to be an important step towards a chemical approach for forming conducting large‐area platelet films of single‐layer graphene. 相似文献
15.
《化学:亚洲杂志》2017,12(10):1052-1056
The β‐cyclodextrin‐assisted aqueous‐exfoliation method was used to prepare transition‐metal dichalcogenide (TMD) nanosheets, in a cheap, highly efficient, scalable and environmentally friendly manner. As study cases, MoS2 and ReS2 nanoflakes were prepared according to this method. Particularly, the effective exfoliation of ReS2 crystals in an aqueous environment was observed for the first time. Moreover, exfoliated nanomaterials can be readily utilized in hydrogen evolution reactions (HERs) as noble‐metal‐free catalysts. This work provides new opportunities for highly efficient exfoliation of TMDs and other 2D nanomaterials into few‐layer nanosheets in aqueous media. Their production process showed high biocompatibility, broad applicability and excellent sustainability. 相似文献
16.
Lucheng Peng Shuai Ye Jun Song Junle Qu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9996-10001
Antimonene, an emerging two‐dimensional material, has garnered tremendous interest due to its intriguing structure and fascinating electronic properties. However, the synthesis of high‐quality few‐layer antimonene nanosheets, which can only be produced by exfoliation or epitaxial growth on exotic substrates, has greatly hindered the development of this new field. Herein, few‐layer hexagonal and functionalized antimonene nanosheets were successfully prepared from SbCl3 solutions for the first time by exclusively promoting their anisotropic growth in a colloidal solution. Oleylamine was selected as the reducing agent, rather than oleic acid, and dodecylthiol was key to preventing the formation of antimony oxide. Additionally, halide ions adsorbed on the surface also influenced the anisotropic growth of hexagonal antimonene nanosheets. Atomic force microscopy (AFM) revealed that the sheets were ≈5 nm thick; Raman spectroscopy and X‐ray diffraction (XRD) revealed a rhombohedral atomic structure (β‐Sb) with excellent stability. 相似文献
17.
Dr. Shu Min Tan Dr. Carmen C. Mayorga-Martinez Prof. Zdeněk Sofer Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(29):6479-6483
Efficient exfoliation and downsizing of Sb2S3 and Bi2S3 layered compounds by using scalable bipolar electrochemistry on their suspensions in aqueous media are here demonstrated. The resulting samples were characterized in detail by transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy; their electrochemistry toward hydrogen evolution was also investigated. Hydrogen evolution ability of exfoliated Sb2S3 and Bi2S3 was investigated and compared to the bulk counterparts. 相似文献
18.
19.
Synthesis of Mg2Al-Cl layered double hydroxide nanosheets in a surfactant-free reverse microemulsion
Jie Xu Lin Zhang Dongxiang Li Jikuan Zhao Wanguo Hou 《Colloid and polymer science》2013,291(11):2515-2521
The synthesis of Mg2Al-Cl layered double hydroxide (LDH) nanosheets in a surfactant-free reverse microemulsion is described. The microemulsion was composed of toluene, isopropanol, and an aqueous solution as the dispersed phase. An aqueous LDH nanosheet dispersion was obtained by a double-microemulsion technique. LDH nanosheets were characterized by X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses. The LDH nanosheets consisted of a single brucite layer without any loading of organic molecules. To the best of our knowledge, this is the first report of a naked LDH monolayer aqueous dispersion being directly obtained. The LDH monolayers can be used as building blocks for LDH-based functional materials. 相似文献
20.
Superconductivity in a Copper(II)‐Based Coordination Polymer with Perfect Kagome Structure 下载免费PDF全文
Xing Huang Dr. Shuai Zhang Liyao Liu Lei Yu Prof. Genfu Chen Prof. Wei Xu Prof. Daoben Zhu 《Angewandte Chemie (International ed. in English)》2018,57(1):146-150
A highly crystalline copper(II) benzenehexathiolate coordination polymer (Cu‐BHT) has been prepared. The two‐dimensional kagome structure has been confirmed by powder X‐ray diffraction, high‐resolution transmission electron microscopy, and high‐resolution scanning transmission electron microscopy. The as‐prepared sample exhibits bulk superconductivity at about 0.25 K, which is confirmed by the zero resistivity, AC magnetic susceptibility, and specific heat measurements. Another diamagnetic transition at about 3 K suggests that there is a second superconducting phase that may be associated with a single layer or few layers of Cu‐BHT. It is the first time that superconductivity has been observed in a coordination polymer. 相似文献