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1.
Chuang Hou Guoan Tai Jinqian Hao Lihang Sheng Bo Liu Zitong Wu 《Angewandte Chemie (International ed. in English)》2020,59(27):10819-10825
Borophene sheets have been synthesized in recent experiments, but the metallic nature and structural instability of the sheets seriously prevent emerging applications. Hydrogenated borophene has been predicted as an ideal material for nanoelectronic applications due to its high stability as well as excellent electronic and mechanical properties. However, the fabrication of hydrogenated borophene is still a great challenge. Here, we demonstrate that hydrogenated borophenes in large quantities can be prepared without any metal substrates by a stepwise in‐situ thermal decomposition of sodium borohydride under hydrogen as the carrier gas. The borophenes with good crystallinity exhibit superior stability in strong acid or base solvents. The structure of the grown borophene is in good agreement with the predicted semiconducting α‐boron sheet. A fabricated borophene‐based memory device shows a high ON/OFF‐current ratio of 3×103 and a low operating voltage of less than 0.35 V as well as good stability. 相似文献
2.
Wan‐Lu Li Tian Jian Xin Chen Teng‐Teng Chen Dr. Gary V. Lopez Prof. Dr. Jun Li Prof. Dr. Lai‐Sheng Wang 《Angewandte Chemie (International ed. in English)》2016,55(26):7358-7363
Monolayer‐boron (borophene) has been predicted with various atomic arrangements consisting of a triangular boron lattice with hexagonal vacancies. Its viability was confirmed by the observation of a planar hexagonal B36 cluster with a central six‐membered ring. Here we report a planar boron cluster doped with a transition‐metal atom in the boron network (CoB18?), suggesting the prospect of forming stable hetero‐borophenes. The CoB18? cluster was characterized by photoelectron spectroscopy and quantum chemistry calculations, showing that its most stable structure is planar with the Co atom as an integral part of a triangular boron lattice. Chemical bonding analyses show that the planar CoB18? is aromatic with ten π‐electrons and the Co atom has strong covalent interactions with the surrounding boron atoms. The current result suggests that transition metals can be doped into the planes of borophenes to create metallo‐borophenes, opening vast opportunities to design hetero‐borophenes with tunable chemical, magnetic, and optical properties. 相似文献
3.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(34):10227-10231
An electron‐counting strategy starting from magnesium boride was used to show the inevitability of hexagonal holes in 2D borophene. The number (hole density, HD) and distribution of the hexagonal holes determine the binding energy per boron atom in monolayer borophenes. The relationship between binding energy and HD changes dramatically when the borophene is placed on a Ag(111) surface. The distribution of holes in borophenes on Ag(111) surfaces depends on the temperature. DFT calculations show that aside from the previously reported S1 and S2 borophene phases, other polymorphs may also be competitive. Plots of the electron density distribution of the boron sheets suggest that the observed STM image of an S2 phase corresponds to a sheet with a HD of 2/15 instead of a sheet with a HD of 1/5. The hole density and the hole distribution echo the distribution of vacancies and extra occupancies in complex β‐rhombohedral boron. 相似文献
4.
B. D. Sanditov Sh. B. Tsydypov D. S. Sanditov V. V. Mantatov 《Polymer Science Series B》2006,48(4):173-176
The Grüneisen lattice parameter has been calculated from the data on the Poisson coefficient for amorphous polymers and glasses. For glassy polymers, the thermodynamic Grüneisen parameter characterizes anharmonicity averaged over intrachain and other vibrational modes, the Grüneisen lattice parameter defines anharmonicity of interchain interactions provided by intermolecular interactions. In the case of alkali silicate glasses, the Grüneisen lattice parameter reflects the anharmonicity of vibrations of ionic sublattice that is formed by alkali-metal ions and nonbridging oxygen atoms. 相似文献
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6.
B. D. Sanditov M. V. Darmaev D. S. Sanditov V. V. Mantatov 《Polymer Science Series A》2007,49(7):837-842
The dependence of the Grüneisen parameter γ D on the anharmonism of lattice oscillations is controlled by γ3 that appears to be a single-value function of the Poisson coefficient. In terms of γ D -γ3 relationship, all solids can be grouped into different structural types. Within each group, the above relationship is linear. The nature of correlation between the Grüneisen parameter and the Poisson coefficient is discussed. 相似文献
7.
Atomic-Scale Insights into the Interlayer Characteristics and Oxygen Reactivity of Bilayer Borophene
Dr. Linfei Li Dr. Jeremy F. Schultz Dr. Sayantan Mahapatra Prof. Xiaolong Liu Prof. Xu Zhang Prof. Mark C. Hersam Prof. Nan Jiang 《Angewandte Chemie (International ed. in English)》2023,62(32):e202306590
Bilayer (BL) two-dimensional boron (i.e., borophene) has recently been synthesized and computationally predicted to have promising physical properties for a variety of electronic and energy technologies. However, the fundamental chemical properties of BL borophene that form the foundation of practical applications remain unexplored. Here, we present atomic-level chemical characterization of BL borophene using ultrahigh vacuum tip-enhanced Raman spectroscopy (UHV-TERS). UHV-TERS identifies the vibrational fingerprint of BL borophene with angstrom-scale spatial resolution. The observed Raman spectra are directly correlated with the vibrations of interlayer boron–boron bonds, validating the three-dimensional lattice geometry of BL borophene. By virtue of the single-bond sensitivity of UHV-TERS to oxygen adatoms, we demonstrate the enhanced chemical stability of BL borophene compared to its monolayer counterpart by exposure to controlled oxidizing atmospheres in UHV. In addition to providing fundamental chemical insight into BL borophene, this work establishes UHV-TERS as a powerful tool to probe interlayer bonding and surface reactivity of low-dimensional materials at the atomic scale. 相似文献
8.
《中国化学快报》2021,32(9):2803-2806
In the field of volatile organic compounds (VOCs) pollution control, adsorption is one of the major control methods, and effective adsorbents are desired in this technology. In this work, the density functional theory (DFT) calculations are employed to investigate the adsorption of typical VOCs molecules on the two-dimensional material borophenes. The results demonstrate that both structure of χ3 and β12 borophene can chemically adsorb ethylene and formaldehyde with forming chemical bonds and releasing large energy. However, other VOCs, including ethane, methanol, formic acid, methyl chloride, benzene and toluene, are physically adsorbed with weak interaction. The analysis of density of states (DOS) reveals that the chemical adsorption changes the conductivity of borophenes, while the physical adsorption has no distinct effect on the conductivity. Therefore, both χ3 and β12 borophene are appropriate adsorbents for selective adsorption of ethylene and formaldehyde, and they also have potential in gas sensor applications due to the obvious conductivity change during the adsorption. 相似文献
9.
Prof. Dr. Zhuhua Zhang Dr. Sharmila N. Shirodkar Dr. Yang Yang Prof. Dr. Boris I. Yakobson 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(48):15623-15628
Boron nanostructures are easily charged but how charge carriers affect their structural stability is unknown. We combined cluster expansion methods with first‐principles calculations to analyze the dependence of the preferred structure of two‐dimensional (2D) boron, or “borophene”, on charge doping controlled by a gate voltage. At a reasonable doping level of 3.12×1014 cm−2, the hollow hexagon concentration in the ground state of 2D boron increases to 1/7 from 1/8 in its charge‐neutral state. The numerical result for the dependence of hollow hexagon concentration on the doping level is well described by an analytical method based on an electron‐counting rule. Aside from in‐plane electronic bonding, the hybridization among out‐of‐plane boron orbitals is crucial for determining the relative stability of different sheets at a given doping level. Our results offer new insight into the stability mechanism of 2D boron and open new ways for the control of the lattice structure during formation. 相似文献
10.
D. S. Sanditov 《Polymer Science Series A》2016,58(5):710-725
Studies concerning the relationship between the value of μ and a number of mechanical and thermal properties of amorphous polymers and glasses are analyzed with the aim to gain information about the origin of Poisson ratio μ in these systems. It is shown that the Poisson ratio features a more pronounced structure-sensitive behavior than the elastic modulus, although the Poisson ratio varies in a narrow range. The relationship between the Poisson ratio and the Grüneisen parameter is substantiated. In this context, the issue of the correlation between harmonic and anharmonic quantities is highlighted. The Poisson ratio is sensitive to lattice dynamics and atomic–molecular structures of polymers and glasses. When light atoms, for example, hydrogen atoms in polyethylene, are replaced with larger and heavier atoms on pendant chains of the macromolecular backbone, anharmonicity increases; that is, lattice Grüneisen parameter γD increases. As a result, the Poisson ratio increases because these quantities are related unambiguously. Conditions of preparing an isotropic material with a negative Poisson ratio (μ < 0) are discussed. The relative ultimate strain of the interatomic bond in glassy systems is a function of the Poisson ratio solely. The frozen elastic strain of amorphous polymers and glasses is likewise a single-valued function of the Poisson ratio. The discussed phenomena are interpreted in terms of the Kuz’menko and Pineda theories and the Berlin–Rothenburg–Bathurst model. 相似文献
11.
Dr. Jordi Poater Prof. Dr. Miquel Solà Prof. Dr. Clara Viñas Prof. Dr. Francesc Teixidor 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7437-7443
A direct connection is established between three‐dimensional aromatic closo boron hydride clusters and planar aromatic [n]annulenes for medium and large boron clusters. In particular, the results prove the existence of a link between the two‐dimensional Hückel rule, as followed by aromatic [n]annulenes, and Wade–Mingos’ rule of three‐dimensional aromaticity, as applied to the aromatic [BnHn]2? closo boron hydride clusters. The closo boron hydride clusters can be categorized into different series, according to the n value of the Hückel (4 n+2) π rule. The distinct categories studied in this work correspond to n=1, 2, and 3. Each category increases in geometrical difficulty but, more importantly, it is possible to associate each category with the number of pentagonal layers in the structure perpendicular to the main axis. Category 1 has one pentagonal layer, category 2 has two, and category 3 has three. 相似文献
12.
《Progress in Surface Science》2023,98(2):100704
Borophene, a two-dimensional (2D) planar boron sheet, has attracted dramatic attention for its unique physical properties that are theoretically predicted to be different from those of bulk boron, such as polymorphism, superconductivity, Dirac fermions, mechanical flexibility and anisotropic metallicity. Nevertheless, it has long been difficult to obtain borophene experimentally due to its susceptibility to oxidation and the strong covalent bonds in bulk forms. With the development of growth technology in ultra-high vacuum (UHV), borophene has been successfully synthesized by molecular beam epitaxy (MBE) supported by substrates in recent years. Due to the intrinsic polymorphism of borophene, the choice of substrates in the synthesis of borophene is pivotal to the atomic structure of borophene. The different interactions and commensuration of borophene on various substrates can induce various allotropes of borophene with distinct atomic structures, which suggests a potential approach to explore and manipulate the structure of borophene and benefits the realization of novel physical and chemical properties in borophene due to the structure–property correspondence. In this review, we summarize the recent research progress in the synthesis of monolayer (ML) borophene on various substrates, including Ag(1 1 1), Ag(1 1 0), Ag(1 0 0), Cu(1 1 1), Cu(1 0 0), Au(1 1 1), Al(1 1 1) and Ir(1 1 1), in which the polymorphism of borophene is present. Moreover, we introduce the realization of bilayer (BL) borophene on Ag(1 1 1), Cu(1 1 1) and Ru(0 0 0 1) surfaces, which possess richer electronic properties, including better thermal stability and oxidation resistance. Then, the stabilization mechanism of polymorphic borophene on their substrates is discussed. In addition, experimental investigations on the unique physical properties of borophene are also introduced, including metallicity, topology, superconductivity, optical and mechanical properties. Finally, we present an outlook on the challenges and prospects for the synthesis and potential applications of borophene. 相似文献
13.
The calculations based on the linear combination of atomic orbitals have been performed for the low‐temperature phase of BaTiO3 crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange–correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO3 rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first‐principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory. © 2012 Wiley Periodicals, Inc. 相似文献
14.
B. D. Sanditov M. V. Darmaev D. S. Sanditov V. V. Mantatov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(7):1232-1233
A correlation between melting points and Grüneisen lattice constants was found for a number of glass-forming oxides. It was established that, at the melting point, the mean energy of the thermal motion of a kinetic unit equaled the ultimate strain work of the interatomic bond corresponding to the quasi-elastic force maximum. 相似文献
15.
Dr. Fang Pu Xia Liu Bailu Xu Prof. Dr. Jinsong Ren Prof. Dr. Xiaogang Qu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(14):4322-4328
Miniaturization of metal–biomolecule frameworks (MBioFs) to the nanometer scale represents a novel strategy for fabricating materials with tunable physical and chemical properties. Herein, we demonstrate a simple, low‐cost, and completely organic solvent‐free strategy for constructing a dl ‐glutamic acid–copper ion‐based three‐dimensional nanofibrous network structure. The building blocks used are available in large quantities and do not require any laborious synthesis or modification. Importantly, we demonstrate with an intriguing example, that the self‐assembly ability of supramolecular nanofibers could be finely tuned with the ligands’ chirality. This offers opportunities for obtaining one‐dimensional hierarchical nanostructures and expands the investigation scope of stereoselective self‐assembly. Furthermore, the material displays good ability in removing anionic dyes from water and inhibits the growth of both Gram positive and Gram negative bacteria, possibly through the contact‐killing mechanism; this indicates potential applications in environmental issues and antimicrobial nanotherapeutics. 相似文献
16.
For the first time, the Grüneisen parameter of silver bromide is calculated as a function of pressure by using the Callaway integral technique and pressure dependence of the thermal conductivity. The values are reported up to 2.0 GPa at 130 and 292 K. Good agreement between theory and experiment is obtained in the low-pressure region where the latter data exist. 相似文献
17.
Dr. Xin Wang Dr. Junwu Liang Dr. Qi You Dr. Jiaqi Zhu Dr. Feier Fang Prof. Yuanjiang Xiang Prof. Jun Song 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23765-23769
Two-dimensional (2D) semiconducting boron nanosheets (few-layer borophene) have been theoretically predicted, but their band gap tunability has not been experimentally confirmed. In this study, hydroxy-functionalized borophene (borophene-OH) with tunable band gap was fabricated by liquid-phase exfoliation using 2-butanol solvent. Surface-energy matching between boron and 2-butanol produced smooth borophene, and the exposed unsaturated B sites generated by B−B bond breaking during exfoliation coordinated with OH groups to form semiconducting borophene-OH, enabling a tunable band gap of 0.65–2.10 eV by varying its thickness. Photoelectrochemical (PEC) measurements demonstrated that the use of borophene-OH to fabricate working electrodes for PEC-type photodetectors significantly enhanced the photocurrent density (5.0 μA cm−2) and photoresponsivity (58.5 μA W−1) compared with other 2D monoelemental materials. Thus, borophene-OH is a promising semiconductor with great optoelectronic potential. 相似文献
18.
Keisuke Fujimoto Prof. Dr. Hideki Yorimitsu Prof. Dr. Atsuhiro Osuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11311-11314
As the most nucleophilic porphyrins, meso‐ or β‐lithiated porphyrins were generated by iodine–lithium exchange reactions of the corresponding iodoporphyrins with n‐butyllithium at ?98 °C. Porphyrinyllithiums thus prepared were used for synthesis of dimesitylporphyrinylboranes through reactions with fluorodimesitylborane. The boryl groups proved to serve as an electron‐accepting unit to alter the photophysical and electrochemical properties. In addition, 5‐diarylamino‐15‐dimesitylboryl‐substituted donor–accepter porphyrins showed increased intramolecular charge‐transfer character in the S1 state. Furthermore, the reaction of β‐lithiated porphyrin with dichloromesitylborane provided a boron‐bridged porphyrin dimer, which exhibited a conjugative interaction between two porphyrin units through the vacant p‐orbital on the boron center. 相似文献
19.
Yanni Lv Xianpeng Shi Jia Fu Qianqian Jia Yuanyuan Lin Hongying Wang Xin Yang Shengli Han 《Biomedical chromatography : BMC》2019,33(9)
Marsdenia tenacissima, or Tongguanteng in Chinese, is a traditional Chinese herb and has a broad application in clinical practice for its pharmacological effects of treating asthma, pneumonia, tonsillitis, pharyngitis tumors, etc. However, few studies have reported the screening of the active components of this medicine for tumor therapy. In this work, a two‐dimensional analytical system was developed to screen antagonists of epidermal growth factor receptor (EGFR) from M. tenacissima. A fraction was retained on the EGFR cell membrane chromatography (CMC) column, separated and identified as tenacissoside G (TG), tenacissoside H (TH) and tenacissoside I (TI) by two‐dimensional HPLC–IT–TOF–MS. Molecular docking and 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2‐H‐tetrazolium bromide (MTT) assay were carried out to assess the activity of TS (including TG, TH and TI). Molecular docking results showed that the binding mode of TS on EGFR is similar to that of gefitinib. The MTT assay demonstrated that gefitinib and TS (especially TI) could inhibit the growth of EGFR highly expressed cell lines in a dose‐dependent manner in the range of 5–50 μmol/L. In conclusion, the two‐dimensional EGFR/CMC–HPLC–IT–TOF–MS system could be a useful approach in drug discovery from traditional Chinese medicines for searching for potential antitumor candidates. 相似文献
20.
《无机化学与普通化学杂志》2018,644(4):253-259
The thermal expansion behavior of Li3AsW7O25 has been studied. The temperature‐dependent development of crystal structural parameters was obtained from Rietveld refinement using neutron time of flight powder diffraction data. Modeling of the lattice thermal expansion was carried out using a Grüneisen first‐order approximation for the zero‐pressure equation of state, where the temperature‐dependent vibrational energy was calculated taking the Debye‐Einstein‐Anharmonicity approach. Temperature‐dependent Raman spectra shed light on some selective modes with unusual anharmonicity. Debye temperatures were calculated using three different theoretical approaches, namely, thermal expansion, mean‐squared isotropic atomic displacement parameter and heat capacity. Similarities as well as discrepancies between the numerical values obtained from different theoretical approaches are discussed. 相似文献