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1.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14753-14758
Creation of new van der Waals heterostructures by stacking different two dimensional (2D) crystals on top of each other in a chosen sequence is the next challenge after the discovery of graphene, mono/few layer of h ‐BN, and transition‐metal dichalcogenides. However, chemical syntheses of van der Waals heterostructures are rarer than the physical preparation techniques. Herein, we demonstrate the kinetic stabilization of 2D ultrathin heterostructure (ca. 1.13–2.35 nm thick) nanosheets of layered intergrowth SnBi2Te4, SnBi4Te7, and SnBi6Te10, which belong to the Snm Bi2n Te3n +m homologous series, by a simple solution based synthesis. Few‐layer nanosheets exhibit ultralow lattice thermal conductivity (κ lat) of 0.3–0.5 W m−1 K−1 and semiconducting electron‐transport properties with high carrier mobility. 相似文献
2.
Cong Liu Lirong Zheng Qian Song Zhenjie Xue Chuanhui Huang Lu Liu Xuezhi Qiao Xiao Li Keyan Liu Tie Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2077-2081
A simple method was adopted in which ultrathin cerium oxide nanoplates (<1.4 nm) were synthesized to increase the surface atomic content, allowing transformation from a face‐centered cubic (fcc) phase to a body‐centered tetragonal (bct) phase. Three types of cerium oxide nanoparticles of different thicknesses (1.2 nm ultrathin nanoplates, 2.2 nm nanoplates, and 5.4 nm nanocubes) were examined using transmission electron microscopy and X‐ray diffraction. The metastable bct phase was observed only in ultrathin nanoplates. Thermodynamic energy analysis confirmed that the surface energy of the ultrathin nanoplates is the cause of the remarkable stabilization of the metastable bct phase. The mechanism of surface energy regulation can be expanded to other metallic oxides, thus providing a new means for manipulating and stabilizing novel materials under ambient conditions that otherwise would not be recovered. 相似文献
3.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(25):7199-7202
An efficient chemical way to finely control the layer‐by‐layer stacking of inorganic nanosheets (NS) is developed by tuning the type and composition of intercalant ion, and the reaction temperature for restacking process. The finely controlled stacking of NS relies on a kinetic control of the self‐assembly of NS in the presence of coordinating organic cations. A critical role of organic cations in this assembly highlights the importance of the appropriate activation energy. Of prime importance is that a fine‐control of the interstratification of 2D NS is highly effective not only in tailoring its pore structure but also in enhancing its electrode activity. The present study clearly demonstrates that the kinetically controlled restacking of NS provides a facile and powerful method to tailor their stacking number and functionality. 相似文献
4.
Byunghyun Min Shaowei Yang Akshay Korde Yeon Hye Kwon Christopher W. Jones Sankar Nair 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(24):8285-8289
High‐quality 2D MFI nanosheet coatings were prepared on α‐alumina hollow fiber supports by vacuum filtration and then transformed into molecular sieving membranes by two sequential hydrothermal treatments. This processing method eliminates the need for specially engineered silica‐based support materials that have so far been necessary to allow the formation of functional membranes from 2D MFI nanosheets. The sequential steps enhance adhesion of the membrane on the fiber support, fill in nanoscale gaps between the 2D nanosheets, and preserve the desirable (0k0) out‐of‐plane orientation without the need of any support engineering or modification. The membrane exhibits high performance for separation of n‐butane from i‐butane, and for other technologically important hydrocarbon separations. The present findings have strong implications on strategies for obtaining thin, highly selective zeolite membranes from 2D zeolites in a technologically scalable manner. 相似文献
5.
Bilal Akram Dr. Wenxiong Shi Hao Zhang Shaheed Ullah Muhammad Khurram Prof. Dr. Xun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8575-8579
A single-step solution-based strategy is used to obtain 2D Janus-like free-standing ultrathin nanosheets build from two structurally unrelated species, that is, polyoxomolybdate (POM) and CoO. A controlled 2D-to-1D morphological transition was achieved by judiciously adjusting the solvent choice. These POM-CoO heterostructures can behave as an ideal catalyst for the epoxidation of styrene. Benefiting from their amphiphilic nature, these 2D POM-CoO nanosheets have also been used as surfactant to emulsify immiscible solvents. It is anticipated that structurally diverse polyoxometalates will offer promise as design elements for variety of structurally and compositionally tunable van der Waals integrated heteromaterials having a broad range applications. 相似文献
6.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(30):8872-8876
Doping in perovskite nanocrystals adopts different mechanistic approach in comparison to widely established doping in chalcogenide quantum dots. The fast formation of perovskites makes the dopant insertions more competitive and challenging. Introducing alkylamine hydrochloride (RNH3Cl) as a promoting reagent, precise controlled doping of MnII in CsPbCl3 perovskite nanocrystals is reported. Simply, by changing the amount of RNH3Cl, the Mn incorporation and subsequent tuning in the excitonic as well as Mn d–d emission intensities are tailored. Investigations suggested that RNH3Cl acted as the chlorinating source, controlled the size, and also helps in increasing the number of particles. This provided more opportunity for Mn ions to take part in reaction and occupied the appropriate lattice positions. Carrying out several reactions with varying reaction parameters, the doping conditions are optimized and the role of the promoting reagent for both doped and undoped systems are compared. 相似文献
7.
Kun Lu Ju Huang Li Ren Chao Li Yejun Guan Bingwen Hu Hao Xu Jingang Jiang Yanhang Ma Peng Wu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6317-6321
Precisely controlled crystal growth endows zeolites with special textural and catalytic properties. A nanosheet mordenite zeolite with a thickness of ca. 11 nm, named as MOR-NS, has been prepared using a well-designed gemini-type amphiphilic surfactant as bifunctional structure-directing agent (SDA). Its benzyl diquarternary ammonium cations structurally directed the formation of MOR topology, whereas the long and hydrophobic hexadecyl tailing group prevented the extensive crystal growth along b axis. This kind of orientated crystallization took place through the inorganic–organic interaction between silica species and SDA molecules present in the whole process. The thin MOR nanosheets, with highly exposed (010) planes and 8-membered ring (MR) windows, exhibited a much improved ethylene selectivity (42.1 %) for methanol-to-olefin (MTO) reactions when compared with conventional bulk MOR crystals (3.3 %). 相似文献
8.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(11):3020-3024
Anionic Keggin polyoxometalates (POMs) and ether linkage‐enriched ammonium ions spontaneously self‐assemble into rectangular ultrathin nanosheets in aqueous media. The structural flexibility of the cation is essential to form oriented nanosheets; as demonstrated by single‐crystal X‐ray diffraction measurements. The difference in initial conditions exerts significant influence on selecting for self‐assembly pathways in the energy landscape. Photoillumination of the POM sheets in pure water causes dissolution of reduced POMs, which allowed site‐specific etching of nanosheets using laser scanning microscopy. By contrast, photoetching was suppressed in aqueous AgNO3 and site‐selective deposition of silver nanoparticles occurred as a consequence of electron transfer from the photoreduced POMs to Ag+ ions on the nanosheet surface. 相似文献
9.
Yawen Wang Le Yu Xiong Wen Lou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(26):7675-7675
10.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(33):9889-9893
Metal–organic framework (MOF) nanosheets could serve as ideal building blocks of molecular sieve membranes owing to their structural diversity and minimized mass‐transfer barrier. To date, discovery of appropriate MOF nanosheets and facile fabrication of high performance MOF nanosheet‐based membranes remain as great challenges. A modified soft‐physical exfoliation method was used to disintegrate a lamellar amphiprotic MOF into nanosheets with a high aspect ratio. Consequently sub‐10 nm‐thick ultrathin membranes were successfully prepared, and these demonstrated a remarkable H2/CO2 separation performance, with a separation factor of up to 166 and H2 permeance of up to 8×10−7 mol m−2 s−1 Pa−1 at elevated testing temperatures owing to a well‐defined size‐exclusion effect. This nanosheet‐based membrane holds great promise as the next generation of ultrapermeable gas separation membrane. 相似文献