共查询到20条相似文献,搜索用时 15 毫秒
1.
Jin Zhang Jia Zhang Dr. Liujiang Zhou Cai Cheng Dr. Chao Lian Jian Liu Prof. Sergei Tretiak Dr. Johannes Lischner Prof. Feliciano Giustino Prof. Sheng Meng 《Angewandte Chemie (International ed. in English)》2018,57(17):4585-4589
Two‐dimensional boron sheets (borophenes) have been successfully synthesized in experiments and are expected to exhibit intriguing transport properties. A comprehensive first‐principles study is reported of the intrinsic electrical resistivity of emerging borophene structures. The resistivity is highly dependent on different polymorphs and electron densities of borophene. Interestingly, a universal behavior of the intrinsic resistivity is well‐described using the Bloch–Grüneisen model. In contrast to graphene and conventional metals, the intrinsic resistivity of borophenes can be easily tuned by adjusting carrier densities, while the Bloch–Grüneisen temperature is nearly fixed at 100 K. This work suggests that monolayer boron can serve as intriguing platform for realizing tunable two‐dimensional electronic devices. 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.
The search for free-standing 2D materials has been one of the most important subjects in the field of studies on 2D materials and their applications. Recently, a free-standing monolayer of hydrogenated boron (HB) sheet has been synthesized by hydrogenation of borophene. The HB sheet is also called borophane, and its application is actively studied in many aspects. Here, we review recent studies on the electronic structures of polymorphic sheets of borophane. A hydrogenated boron sheet with a hexagonal boron frame was shown to have a semimetallic electronic structure by experimental and theoretical analyses. A tight-binding model that reproduces the electronic structure was given and it allows easy estimation of the properties of the material. Hydrogenated boron sheets with more complicated nonsymmorphic boron frames were also analyzed. Using the symmetry restrictions from the nonsymmorphic symmetry and the filling factor of hydrogenated boron sheets, the existence of a Dirac nodal line was suggested. These studies provide basic insights for research on and device applications of hydrogenated boron sheets. 相似文献
5.
6.
《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
7.
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
8.
Dr. Ying Xiao Dr. Chuangang Hu Prof. Liangti Qu Prof. Changwen Hu Prof. Minhua Cao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14271-14278
A facile and low‐cost strategy is developed to prepare three‐dimensional (3D) macroporous NiCo2O4 sheets, which can be used as a highly efficient non‐noble metal electrocatalyst for the oxygen reduction reaction (ORR) in alkaline conditions. The as‐obtained sheets have a thickness of about 150 nm and feature a typical 3D macroporous structure with pore volumes of up to 0.23 cm3 g?1, which could decrease the mass transport resistance and allow easier access of the reactants to the active surface sites. The as‐prepared macroporous NiCo2O4 sheets exhibit high electrocatalytic activity for ORR with a four‐electron pathway, good long‐term stability and high tolerance against methanol. The unique 3D macroporous structure and intrinsic properties may be responsible for their high performance. 相似文献
9.
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
10.
Alexandra Santos-Putungan Khloe Ysabelle Diego Darwin Barayang Putungan 《中国化学会会志》2023,70(11):1950-1956
The adsorption of CO, CO2, and N2O on a newly found α-type reconstructed form of borophene was investigated via density functional theory calculations. It is revealed that the new α-type reconstructed borophene structure consists of several large holes, and has the same order of stability as the predicted α1-borophene in Wu et al. On the pristine reconstructed borophene case, CO and CO2 adsorb moderately and weakly, respectively. Interestingly, N2O spontaneously dissociated on the α-type reconstructed borophene. Upon the application of biaxial strain, especially at 10%, the adsorption of CO and CO2 on the reconstructed borophene becomes significantly enhanced, and this is attributed to changes in the density of states near the Fermi level of the reconstructed borophene. 相似文献
11.
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
12.
Feng Zou Prof. Xianluo Hu Dr. Yongming Sun Dr. Wei Luo Fangfang Xia Long Qie Yan Jiang Prof. Yunhui Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(19):6027-6033
Zn2GeO4/N‐doped graphene nanocomposites have been synthesized through a fast microwave‐assisted route on a large scale. The resulting nanohybrids are comprised of Zn2GeO4 nanorods that are well‐embedded in N‐doped graphene sheets by in situ reducing and doping. Importantly, the N‐doped graphene sheets serve as elastic networks to disperse and electrically wire together the Zn2GeO4 nanorods, thereby effectively relieving the volume‐expansion/contraction and aggregation of the nanoparticles during charge and discharge processes. We demonstrate that an electrode that is made of the as‐formed Zn2GeO4/N‐doped graphene nanocomposite exhibits high capacity (1463 mAh g?1 at a current density of 100 mA g?1), good cyclability, and excellent rate capability (531 mAh g?1 at a current density of 3200 mA g?1). Its superior lithium‐storage performance could be related to a synergistic effect of the unique nanostructured hybrid, in which the Zn2GeO4 nanorods are well‐stabilized by the high electronic conduction and flexibility of N‐doped graphene sheets. This work offers an effective strategy for the fabrication of functionalized ternary‐oxide‐based composites as high‐performance electrode materials that involve structural conversion and transformation. 相似文献
13.
Nasir Mahmood Chenzhen Zhang Jie Jiang Fei Liu Prof. Yanglong Hou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(16):5183-5190
Cobalt sulfide is a good candidate for both lithium ion batteries (LIBs) and cathodic oxygen reduction reaction (ORR), but low conductivity, poor cyclability, capacity fading, and structural changes hinder its applications. The incorporation of graphene into Co3S4 makes it a promising electrode by providing better electrochemical coupling, enhanced conductivity, fast mobility of ions and electrons, and a stabilized structure due to its elastic nature. With the objective of achieving high‐performance composites, herein we report a facile hydrothermal process for growing Co3S4 nanotubes (NTs) on graphene (G) sheets. Electrochemical impedance spectroscopy (EIS) verified that graphene dramatically increases the conductivity of the composites to almost twice that of pristine Co3S4. Electrochemical measurements indicated that the as‐synthesized Co3S4/G composites exhibit good cyclic stability and a high discharge capacity of 720 mA h g?1 up to 100 cycles with 99.9 % coulombic efficiency. Furthermore, the composites react with dissolved oxygen in the ORR by four‐ and two‐electron mechanisms in both acidic and basic media with an onset potential close to that of commercial Pt/C. The stability of the composites is much higher than that of Pt/C, and exhibit high methanol tolerance. Thus, these properties endorse Co3S4/G composites as auspicious candidates for both LIBs and ORR. 相似文献
14.
Vicente J. Margarit Marta E. Martínez‐Armero Dr. M. Teresa Navarro Dr. Cristina Martínez Prof. Avelino Corma 《Angewandte Chemie (International ed. in English)》2015,54(46):13724-13728
A two‐dimensional zeolite with the topology of MWW sheets has been obtained by direct synthesis with a combination of two organic structure‐directing agents. The resultant material consists of approximately 70 % single and double layers and displays a well‐structured external surface area of about 300 m2 g?1. The delaminated zeolite prepared by means of this single‐step synthetic route has a high delamination degree, and the structural integrity of the MWW layers is well preserved. The new zeolite material displayed excellent activity, selectivity, and stability when used as a catalyst for the alkylation of benzene with propylene and found to be superior to the catalysts that are currently used for producing cumene. 相似文献
15.
Synthesis and Investigation of the V‐shaped Tröger′s Base Derivatives as Hole‐transporting Materials
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Titas Braukyla Dr. Nobuya Sakai Dr. Maryte Daskeviciene Dr. Vygintas Jankauskas Egidijus Kamarauskas Dr. Tadas Malinauskas Prof. Henry J. Snaith Prof. Vytautas Getautis 《化学:亚洲杂志》2016,11(14):2049-2056
V‐shaped Tröger′s base core has been investigated as a central linking unit in the synthesis of new charge‐transporting materials for optoelectronic applications. The studied molecules have been synthesized in two steps from relatively inexpensive starting materials, and demonstrate high glass transition temperatures, good stability of the amorphous state, and comparatively high hole drift mobility (up to 0.011 cm2 V?1 s?1). 相似文献
16.
HOMO Stabilisation in π‐Extended Dibenzotetrathiafulvalene Derivatives for Their Application in Organic Field‐Effect Transistors
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Dr. Yan Geng Dr. Raphael Pfattner Antonio Campos Prof. Wei Wang Dr. Olivier Jeannin Dr. Jürg Hauser Dr. Joaquim Puigdollers Prof. Stefan T. Bromley Prof. Silvio Decurtins Prof. Jaume Veciana Prof. Concepció Rovira Dr. Marta Mas‐Torrent Dr. Shi‐Xia Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(50):16672-16679
Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB‐TTF) central core and a 2,1,3‐chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB‐TTF, have been synthesised as active materials for organic field‐effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron‐withdrawing 2,1,3‐chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution‐processed single‐crystal transistors exhibit high performance with a hole mobility up to 0.04 cm2 V?1 s?1 as well as good ambient stability. 相似文献
17.
First-Principles Study on Electronic and Optical Properties of Graphene-Like Boron Phosphide Sheets
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Two-dimensional semiconducting materials with moderate band gap and high carrier mobil-ity have a wide range of applications for electronics and optoelectronics in nanoscale. On the basis of first-principles calculations, we perform a comprehensive study on the electronics and optical properties of graphene-like boron phosphide (BP) sheets. The global structure search and first-principles based molecular dynamic simulation indicate that two-dimensional BP sheet has a graphene-like global minimum structure with high stability. BP monolayer is semiconductor with a direct band gap of 1.37 eV, which reduces with the number of layers. Moreover, the band gaps of BP sheets are insensitive to the applied uniaxial strain.= The calculated mobility of electrons in BP monolayer is as high as 106 cm2/(V·s). Lastly, the MoS2/BP van der Waals heterobilayers are investigated for photovoltaic applications, and their power conversion efficiencies are estimated to be in the range of 17.7%-19.7%. This study implies the potential applications of graphene-like BP sheets for electronic and optoelectronic devices in nanoscale. 相似文献
18.
《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
19.
Postsynthetic Functionalization of Three‐Dimensional Covalent Organic Frameworks for Selective Extraction of Lanthanide Ions
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Qiuyu Lu Yunchao Ma Hui Li Xinyu Guan Yusran Yusran Prof. Ming Xue Prof. Qianrong Fang Prof. Yushan Yan Prof. Shilun Qiu Prof. Valentin Valtchev 《Angewandte Chemie (International ed. in English)》2018,57(21):6042-6048
Chemical functionalization of covalent organic frameworks (COFs) is critical for tuning their properties and broadening their potential applications. However, the introduction of functional groups, especially to three‐dimensional (3D) COFs, still remains largely unexplored. Reported here is a general strategy for generating a 3D carboxy‐functionalized COF through postsynthetic modification of a hydroxy‐functionalized COF, and for the first time exploration of the 3D carboxy‐functionalized COF in the selective extraction of lanthanide ions. The obtained COF shows high crystallinity, good chemical stability, and large specific surface area. Furthermore, the carboxy‐functionalized COF displays high metal loading capacities together with excellent adsorption selectivity for Nd3+ over Sr2+ and Fe3+ as confirmed by the Langmuir adsorption isotherms and ideal adsorbed solution theory (IAST) calculations. This study not only provides a strategy for versatile functionalization of 3D COFs, but also opens a way to their use in environmentally related applications. 相似文献
20.
Putikam Raghunath Yun‐Min Lee Shang‐Ying Wu Jong‐Shinn Wu Ming‐Chang Lin 《International journal of quantum chemistry》2013,113(12):1735-1746
Hydrogen atoms and SiHx (x = 1–3) radicals coexist during the chemical vapor deposition (CVD) of hydrogenated amorphous silicon (a‐Si:H) thin films for Si‐solar cell fabrication, a technology necessitated recently by the need for energy and material conservation. The kinetics and mechanisms for H‐atom reactions with SiHx radicals and the thermal decomposition of their intermediates have been investigated by using a high high‐level ab initio molecular‐orbital CCSD (Coupled Cluster with Single and Double)(T)/CBS (complete basis set extrapolation) method. These reactions occurring primarily by association producing excited intermediates, 1SiH2, 3SiH2, SiH3, and SiH4, with no intrinsic barriers were computed to have 75.6, 55.0, 68.5, and 90.2 kcal/mol association energies for x = 1–3, respectively, based on the computed heats of formation of these radicals. The excited intermediates can further fragment by H2 elimination with 62.5, 44.3, 47.5, and 56.7 kcal/mol barriers giving 1Si, 3Si, SiH, and 1SiH2 from the above respective intermediates. The predicted heats of reaction and enthalpies of formation of the radicals at 0 K, including the latter evaluated by the isodesmic reactions, SiHx + CH4 = SiH4 + CHx, are in good agreement with available experimental data within reported errors. Furthermore, the rate constants for the forward and unimolecular reactions have been predicted with tunneling corrections using transition state theory (for direct abstraction) and variational Rice–Ramsperger–Kassel–Marcus theory (for association/decomposition) by solving the master equation covering the P,T‐conditions commonly employed used in industrial CVD processes. The predicted results compare well experimental and/or computational data available in the literature. © 2013 Wiley Periodicals, Inc. 相似文献