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Sebastian Grieger Beata M. Szydłowska Vaishnavi J. Rao Eva Steinmann Marcus Dodds Zahra Gholamvand Georg S. Duesberg Jana Zaumseil Claudia Backes 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13889-13896
In recent years, various functionalization strategies for transition-metal dichalcogenides have been explored to tailor the properties of materials and to provide anchor points for the fabrication of hybrid structures. Herein, new insights into the role of the surfactant in functionalization reactions are described. Using the spontaneous reaction of WS2 with chloroauric acid as a model reaction, the regioselective formation of gold nanoparticles on WS2 is shown to be heavily dependent on the surfactant employed. A simple model is developed to explain the role of the chosen surfactant in this heterogeneous functionalization reaction. The surfactant coverage is identified as the crucial element that governs the dominant reaction pathway and therefore can severely alter the reaction outcome. This study shows the general importance of the surfactant choice and how detrimental or beneficial a certain surfactant can be to the desired functionalization. 相似文献
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Low‐Temperature Solution Synthesis of Few‐Layer 1T ′‐MoTe2 Nanostructures Exhibiting Lattice Compression 下载免费PDF全文
Yifan Sun Yuanxi Wang Du Sun Bruno R. Carvalho Carlos G. Read Chia‐hui Lee Zhong Lin Kazunori Fujisawa Prof. Joshua A. Robinson Prof. Vincent H. Crespi Prof. Mauricio Terrones Prof. Raymond E. Schaak 《Angewandte Chemie (International ed. in English)》2016,55(8):2830-2834
Molybdenum ditelluride, MoTe2, is emerging as an important transition‐metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T ′ polymorph of MoTe2 is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H‐MoTe2 is more stable and therefore more accessible synthetically. Metastable 1T ′‐MoTe2 forms directly in solution at 300 °C as uniform colloidal nanostructures that consist of few‐layer nanosheets, which appear to exhibit an approx. 1 % lateral lattice compression relative to the bulk analogue. Density functional theory calculations suggest that small grain sizes and polycrystallinity stabilize the 1T ′ phase in the MoTe2 nanostructures and suppress its transformation back to the more stable 2H polymorph through grain boundary pinning. Raman spectra of the 1T ′‐MoTe2 nanostructures exhibit a laser energy dependence, which could be caused by electronic transitions. 相似文献
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Dr. Claudia Backes Dr. Nina C. Berner Xin Chen Paul Lafargue Pierre LaPlace Mark Freeley Prof. Georg S. Duesberg Prof. Jonathan N. Coleman Dr. Aidan R. McDonald 《Angewandte Chemie (International ed. in English)》2015,54(9):2638-2642
Layered two‐dimensional (2D) inorganic transition‐metal dichalchogenides (TMDs) have attracted great interest as a result of their potential application in optoelectronics, catalysis, and medicine. However, methods to functionalize and process such 2D TMDs remain scarce. We have established a facile route towards functionalized layered MoS2. We found that the reaction of liquid‐exfoliated 2D MoS2, with M(OAc)2 salts (M=Ni, Cu, Zn; OAc=acetate) yielded functionalized MoS2–M(OAc)2 materials. Importantly, this method furnished the 2H‐polytype of MoS2 which is a semiconductor. X‐ray photoelectron spectroscopy (XPS), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT–IR), and thermogravimetric analysis (TGA) provide strong evidence for the coordination of MoS2 surface sulfur atoms to the M(OAc)2 salt. Interestingly, functionalization of 2H‐MoS2 allows for its dispersion/processing in more conventional laboratory solvents. 相似文献
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Lanfang Wang Chuang Song Yi Shi Liyun Dang Ying Jin Hong Jiang Prof. Dr. Qingyi Lu Prof. Dr. Feng Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5575-5582
Two‐dimensional nanosheets with high specific surface areas and fascinating physical and chemical properties have attracted tremendous interests because of their promising potentials in both fundamental research and practical applications. However, the problem of developing a universal strategy with a facile and cost‐effective synthesis process for multi‐type ultrathin 2 D nanostructures remains unresolved. Herein, we report a generalized low‐temperature fabrication of scalable multi‐type 2 D nanosheets including metal hydroxides (such as Ni(OH)2, Co(OH)2, Cd(OH)2, and Mg(OH)2), metal oxides (such as ZnO and Mn3O4), and layered mixed transition‐metal hydroxides (Ni‐Co LDH, Ni‐Fe LDH, Co‐Fe LDH, and Ni‐Co‐Fe layered ternary hydroxides) through the rational employment of a green soft‐template. The synthesized crystalline inorganic nanosheets possess confined thickness, resulting in ultrahigh surface atom ratios and chemically reactive facets. Upon evaluation as electrode materials for pseudocapacitors, the Ni‐Co LDH nanosheets exhibit a high specific capacitance of 1087 F g?1 at a current density of 1 A g?1, and excellent stability, with 103 % retention after 500 cycles. This strategy is facile and scalable for the production of high‐quality ultrathin crystalline inorganic nanosheets, with the possibility of extension to the preparation of other complex nanosheets. 相似文献
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Dr. Rui Li Dr. Yousong Liu Dr. Zhaoqian Li Dr. Jinpeng Shen Dr. Yuntao Yang Prof. Dr. Xudong Cui Dr. Guangcheng Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):272-278
A single‐layered intermolecular carbonization method was applied to synthesize single‐layered nitrogen‐doped graphene quantum dots (N‐GQDs) by using 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) as the only precursor. In this method, the gas produced in the pyrolysis of TATB assists with speeding up of the reactions and expanding the layered distance, so that it facilitates the formation of single‐layered N‐GQDs (about 80 %). The symmetric intermolecular carbonizations of TATB arrayed in a plane and six nitrogen‐containing groups ensure small, uniform sizes (2–5 nm) of the resulting products, and provide high nitrogen‐doping concentrations (N/C atomic ratio ca. 10.6 %). In addition to release of the produced gas, TATB is almost completely converted into aggregated N‐GQDs; thus, relatively higher production rates are possible with this approach. Investigations show that the as‐produced N‐GQDs have superior fluorescent characteristics; high water solubility, biocompatibility, and low toxicity; and are ready for potential applications, such as biomedical imaging and optoelectronic devices. 相似文献
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MoS2/WS2‐Graphene Composites through Thermal Decomposition of Tetrathiomolybdate/Tetrathiotungstate for Proton/Oxygen Electroreduction 下载免费PDF全文
Jan Luxa Jack Fawdon Zdeněk Sofer Vlastimil Mazánek Martin Pumera 《Chemphyschem》2016,17(18):2890-2896
MoS2 and WS2 have been prepared on a conductive graphene support by thermal reduction of tetrathiotungstate/tetrathiomolybdate and graphite oxide. Whereas the catalytic properties towards hydrogen evolution are strongly influenced by the Magnéli phases formed as a byproduct during the synthesis, the catalytic activity towards oxygen reduction of these composite materials is not affected by this phenomenon and these materials exhibit high catalytic activity towards this industrially important reaction. 相似文献
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Shogo Okumura Takuya Komine Erika Shigeki Prof. Dr. Kazuhiko Semba Prof. Dr. Yoshiaki Nakao 《Angewandte Chemie (International ed. in English)》2018,57(4):929-932
We report meta‐ and para‐selective linear alkylation reactions of anilides with alkenes by nickel/N‐heterocyclic carbene (NHC) and aluminum catalysis. With a less bulky NHC, the alkylation reaction of N‐methyl‐N‐phenylcyclohexanecarboxamides proceeded mainly at the meta position. In contrast, a bulky NHC ligand led to the para‐selective alkylation of N‐sec‐alkyl anilides. 相似文献
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Dr. Yi‐Tao Liu Zhen Tan Prof. Xu‐Ming Xie Zhi‐Feng Wang Prof. Xiong‐Ying Ye 《化学:亚洲杂志》2013,8(4):817-823
Inorganic graphene analogues (IGAs) are a huge and fascinating family of compounds that have extraordinary electronic, mechanical, and thermal properties. However, one of the largest problems that face the industrial application of IGAs is their poor processability, which has led to a “bottlenecking” in the development of freestanding, large‐area, IGA‐based thin‐film devices. Herein, we report a facile and cost‐efficient method to chemically modify IGAs by using their abundant coordination atoms (S, O, and N). Taking MoS2 as an example, we have prepared homogeneous “solution” systems, in which MoS2 nanosheets are chemically cross‐linked through a carboxylate‐containing polymeric ligand, poly(methyl methacrylate) (PMMA), by copper‐ion coordination. Bonding interactions between C?O bonds and sulfur atoms through copper ions were confirmed by various characterization techniques, such as UV/Vis, FTIR, and Raman spectroscopy and XPS. By using our method, freestanding MoS2 paper with significantly improved mechanical properties was obtained, thus laying the basis for the mass production of large‐area MoS2‐based thin‐film devices. Furthermore, copper‐ion coordination was also applied to MoS2/PMMA nanocomposites. Direct and strong nanofiller/matrix bonding interactions facilitate efficient load transfer and endow the polymeric nanocomposites with an excellent reinforcement effect. This method may pave a new way to high‐strength polymeric nanocomposites with superior frictional properties, flame retardance, and oxidation resistance. 相似文献
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Recognition and Site‐Selective Transformation of Monosaccharides by Using Copper(II) Catalysis 下载免费PDF全文
Dr. I‐Hon Chen Kevin G. M. Kou Diane N. Le Colin M. Rathbun Prof. Dr. Vy M. Dong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5013-5018
We demonstrate copper(II)‐catalyzed acylation and tosylation of monosaccharides. Various carbohydrate derivatives, including glucopyranosides and ribofuranosides, are obtained in high yields and regioselectivities. Using this versatile strategy, the site of acylation can be switched by choice of ligand. Preliminary mechanistic studies support nucleophilic addition of a copper–sugar complex to the acyl chloride to be turnover limiting. 相似文献
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Prof. Da‐Ren Hang Krishna Hari Sharma Prof. Chun‐Hu Chen Sk Emdadul Islam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12777-12784
We exploit the utilization of two‐dimensional (2D) molybdenum oxide nanoflakes as a co‐catalyst for ZnO nanorods (NRs) to enhance their photocatalytic performance. The 2D nanoflakes of orthorhombic α‐MoO3 were synthesized through a sonication‐aided exfoliation technique. The 2D MoO3 nanoflakes can be further converted to substoichiometric quasi‐metallic MoO3?x by using UV irradiation. Subsequently, 1D–2D MoO3/ZnO NR and MoO3?x/ZnO NR composite photocatalysts have been successfully synthesized. The photocatalytic performances of the novel nanosystems in the decomposition of methylene blue are studied by using UV‐ and visible‐illumination setup. The incorporated 2D nanoflakes show a positive influence on the photocatalytic activity of the ZnO. The obtained rate constant values follow the order of pristine ZnO NR<MoO3/ZnO NR<MoO3?x/ZnO NR composites. The enhancement of the photocatalytic efficiency can be ascribed to a fast charge carrier separation and transport within the heterojunctions of the MoO3/ZnO NRs. In particular, the best photocatalytic performance of the MoO3?x/ZnO NR composite can be additionally attributed to a quasi‐metallic conductivity and substoichiometry‐induced mid‐gap states, which extend the light absorption range. A tentative photocatalytic degradation mechanism was proposed. The strategy presented in this work not only demonstrates that coupling with nanoscale molybdenum oxide nanoflakes is a promising approach to significantly enhance the photocatalytic activity of ZnO but also hints at new type of composite catalyst with extended applications in energy conversion and environmental purification. 相似文献
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Marian Rauser Daniel P. Warzecha Prof. Dr. Meike Niggemann 《Angewandte Chemie (International ed. in English)》2018,57(20):5903-5907
In analogy to the classical reaction of C?B bonds with peroxides, the first oxidative functionalization of aminoboranes through a 1,2‐N migration was realized. Readily available aliphatic nitro compounds are thereby transformed into N‐ and O‐functionalized hydroxylamines in a single synthetic operation. Addition of hazardous peroxides is avoided. Instead, the insertion of O2, as the terminal oxidant, into Zn?C bonds provides the necessary peroxides. The required zinc organyls, in turn, are formed through a boron‐to‐zinc exchange, from an organoboronic ester byproduct of the nitro‐to‐aminoborane transformation. 相似文献
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Composition‐Tailored 2 D Mn1−xRuxO2 Nanosheets and Their Reassembled Nanocomposites: Improvement of Electrode Performance upon Ru Substitution 下载免费PDF全文
Su‐Jeong Kim In Young Kim Dr. Sharad B. Patil Seung Mi Oh Dr. Nam‐Suk Lee Prof. Dr. Seong‐Ju Hwang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):5132-5140
Composition‐tailored Mn1?xRuxO2 2 D nanosheets and their reassembled nanocomposites with mesoporous stacking structure are synthesized by a soft‐chemical exfoliation reaction and the subsequent reassembling of the exfoliated nanosheets with Li+ cations, respectively. The tailoring of the chemical compositions of the exfoliated Mn1?xRuxO2 2 D nanosheets and their lithiated nanocomposites can be achieved by adopting the Ru‐substituted layered manganese oxides as host materials for exfoliation reaction. Upon the exfoliation–reassembling process, the substituted ruthenium ions remain stabilized in the layered Mn1?xRuxO2 lattice with mixed Ru3+/Ru4+ oxidation state. The reassembled Li–Mn1?xRuxO2 nanocomposites show promising pseudocapacitance performance with large specific capacitances of approximately 330 F g?1 for the second cycle and approximately 360 F g?1 for the 500th cycle and excellent cyclability, which are superior to those of the unsubstituted Li–MnO2 homologue and many other MnO2‐based materials. Electrochemical impedance spectroscopy analysis provides strong evidence for the enhancement of the electrical conductivity of 2 D nanostructured manganese oxide upon Ru substitution, which is mainly responsible for the excellent electrode performance of Li–Mn1?xRuxO2 nanocomposites. The results underscore the powerful role of the composition‐controllable metal oxide 2 D nanosheets as building blocks for exploring efficient electrode materials. 相似文献
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Yu‐Biao Chen Dr. Ling Chen Prof. Dr. Li‐Ming Wu Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(35):11069-11075
Uniform Cu2S nanodisks have been synthesized from a well‐characterized layered copper thiolate precursor by structure‐controlling solventless thermolysis at 200–220 °C under a N2 atmosphere. The development from small Cu2S nanoparticles (diameter ≈3 nm) to nanodisks (diameter 8.3 nm) and then to faceted nanodisks (diameter 27.5 nm, thickness 12.7 nm) is accompanied by a continuous phase transition from metastable orthorhombic to monoclinic Cu2S, the ripening of small particles by aggregation, and finally the crystallization process. The growth of the nanoproduct is constrained by the crystal structure of the precursor and the in situ‐generated thiol molecules. Such controlled anisotropic growth leads to a nearly constant thickness of faceted nanodisks with different diameters, which has been confirmed by TEM observations and optical absorption measurements. 相似文献
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Hao Bin Wu Prof. Xiong Wen Lou Prof. Huey Hoon Hng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(7):2094-2099
Layered protonated titanates (LPTs), a class of interesting inorganic layered materials, have been widely studied because of their many unique properties and their use as precursors to many important TiO2‐based functional materials. In this work, we have developed a facile solvothermal method to synthesize hierarchical spheres (HSs) assembled from ultrathin LPT nanosheets. These LPT hierarchical spheres possess a porous structure with a large specific surface area and high stability. Importantly, the size and morphology of the LPT hierarchical spheres are easily tunable by varying the synthesis conditions. These LPT HSs can be easily converted to anatase TiO2 HSs without significant structural alteration. Depending on the calcination atmosphere of air or N2, pure anatase TiO2 HSs or carbon‐supported TiO2 HSs, respectively, can be obtained. Remarkably, both types of TiO2 HSs manifest excellent cyclability and rate capability when evaluated as anode materials for high‐power lithium‐ion batteries. 相似文献
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Single‐Layered Ultrasmall Nanoplates of MoS2 Embedded in Carbon Nanofibers with Excellent Electrochemical Performance for Lithium and Sodium Storage 下载免费PDF全文
Dr. Changbao Zhu Dr. Xiaoke Mu Prof. Peter A. van Aken Prof. Yan Yu Prof. Joachim Maier 《Angewandte Chemie (International ed. in English)》2014,53(8):2152-2156
The preparation and electrochemical storage behavior of MoS2 nanodots—more precisely single‐layered ultrasmall nanoplates—embedded in carbon nanowires has been studied. The preparation is achieved by an electrospinning process that can be easily scaled up. The rate performance and cycling stability of both lithium and sodium storage were found to be outstanding. The storage behavior is, moreover, highly exciting from a fundamental point of view, as the differences between the usual storage modes—insertion, conversion, interfacial storage—are beneficially blurred. The restriction to ultrasmall reaction domains allows for an almost diffusion‐less and nucleation‐free “conversion”, thereby resulting in a high capacity and a remarkable cycling performance. 相似文献