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1.
The surface plasmon polaritons (SPPs) in monolayer MoS2 nanostructures are theoretically investigated in detail. Our study shows that the strong SPPs are induced in gigahertz (GHz) frequency range. The frequencies of SPPs are very sensitive on the substrates in the nanostructures. Moreover, the frequency of such SPPs can be controlled by varying the electron densities. Our study can be applied to understand the recent experimental results and is relevant to the applications of plasmonic nano-devices based on MoS2.  相似文献   

2.
MoS2 quantum dots (QDs) have been obtained in colloidal suspensions by 532 nm laser ablation (7 ns fwhp/pulse, 50 mJ/pulse) of commercial MoS2 particles in acetonitrile. High-resolution transmission electron microscopy images show a lateral size distribution from 5 to 20 nm, but a more homogeneous particle size of 20 nm can be obtained by silica gel chromatography purification in acetonitrile. MoS2 QDs obtained by laser ablation are constituted by 3–6 MoS2 layers (1.8–4 nm thickness) and exhibit photoluminescence whose λPL varies from 430 to 530 nm depending on the excitation wavelength. As predicted by theory, the confinement effect and the larger periphery in MoS2 QDs increasing the bandgap and having catalytically active edges are reflected in an enhancement of the photocatalytic activity for H2 generation upon UV–Vis irradiation using CH3OH as sacrificial electron donor due to the increase in the reduction potential of conduction band electrons and the electron transfer kinetics.  相似文献   

3.
Areas of single-layer MoS2 film can be prepared in a tube furnace without the need for temperature control. The films were characterized by means of Raman spectroscopy, photoluminescence, low-energy electron diffraction and microscopy, and X-ray photoelectron spectroscopy and mapping. Transport measurements show n-doped material with a mobility of 0.26 cm2 V-1 s-1.  相似文献   

4.
Regular hexagonal MoS2 microflakes with high yield were grown from MoO3 precursor by a sulfurization process using S powders as sulfuration reducer. The precursors, long and smooth MoO3 microbelts, were synthesized through a direct oxidation reaction of Mo plates in air. X-ray powder diffraction and scanning electron microscopy revealed that the sulfurized products were hexagonal MoS2 with regular hexagonal flake-like morphology. The results of transmission electron microscopy examinations demonstrated that the microflakes were single crystalline MoS2. Elemental analysis by EDAX and XPS showed that the microflakes consist of Mo and S with the atomic ratio near to 0.5. Factors influencing the formation of the product were systematically studied. PACS 81.15.Gh; 81.15.Kk; 81.05.Hd; 78.67.Pt; 82.40.Ck  相似文献   

5.
The structural transformation of MoO3 nanobelts into MoS2 nanotubes using a simple sulfur source has been reported. This transformation has been extensively investigated using electron microscopic and spectroscopic techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), electron diffraction (ED), and energy-dispersive X-ray analysis (SEM-EDAX and TEM-EDX). The method described in this report will serve as a generic route for the transformation of other oxide nanostructures into the chalcogenide nanostructures.  相似文献   

6.
The electronic structures of a MoS2 monolayer are investigated with the all-electron first principle calculations based on the density functional theory (DFT) and the spin-orbital couplings (SOCs). Our results show that the monolayer MoS2 is a direct band gap semiconductor with a band gap of 1.8 eV. The SOCs and d-electrons in Mo play a very significant role in deciding its electronic and optical properties. Moreover, electronic elementary excitations are studied theoretically within the diagrammatic self-consistent field theory. Under random phase approximation, it shows that two branches of plasmon modes can be achieved via the conduction-band transitions due to the SOCs, which are different from the plasmons in a two-dimensional electron gas and graphene owing to the quasi-linear energy dispersion in single-layer MoS2. Moreover, the strong optical absorption up to 105 cm-1 and two optical absorption edges I and II can be observed. This study is relevant to the applications of monolayer MoS2 as an advanced photoelectronic device.  相似文献   

7.
Two-dimensional (2D) MoS2 is used as a catalyst or support and has received increased research interest because of its superior structural and electronic properties compared with those of bulk structures. In this article, we illustrate the active sites of 2D MoS2 and various strategies for enhancing its intrinsic catalytic activity. The recent advances in the use of 2D MoS2-based materials for applications such as thermocatalysis, electrocatalysis, and photocatalysis are discussed. We also discuss the future opportunities and challenges for 2D MoS2-based materials, in both fundamental research and industrial applications.  相似文献   

8.
First-principles calculation was used to study the interfacial properties of theSrRuO3 (1 1 1)/MoS2(√3 × √3) heterojunction. It is found that the huge magneticmoments in of monolayer MoS2 largely originate from the Ru-S hybridization for theRu-terminated interface. Moreover, for the SrO-terminated interface, we studied mainly themetal and semiconductor contact characteristic. The calculated results show that theSchottky barrier height can be significantly reduced to zero for the SrO-terminatedinterface. Schottky barrier heights dominate the transport behavior of theSrRuO3/MoS2 interface. Our results not only have potentialapplications in spintronics devices, but also are in favour of the scaling of field effecttransistors.  相似文献   

9.
We report about results from density functional based calculations on structural, electronic and transport properties of one-dimensional MoS2 nanoribbons with different widths and passivation of their edges. The edge passivation influences the electronic and transport properties of the nanoribbons. This holds especially for nanoribbons with zigzag edges. Nearly independent from the passivation the armchair MoS2 nanoribbons are semiconductors and their band gaps exhibit an almost constant value of 0.42 eV. Our results illustrate clearly the edge priority on the electronic properties of MoS2 nanoribbons and indicate problems for doping of MoS2 nanoribbons.  相似文献   

10.
In the present work we report the synthesis of MoS2 nanotubes with diameters greater than 10 nm using a template method. The length and properties of these nanotubes are a direct result of the preparation method. High-resolution transmission electron microscopy is used to study the structure of these highly curved entities. Molecular dynamics simulations of MoS2 nanotubes reveal that one of the stable forms of the nanotubes is a twisted one. The twisting of the nanotubes produces a characteristic contrast in the images, which is also studied using simulation methods. The analysis of the local contrast close to the perpendicular orientation shows geometrical arrays of dots in domain-like structures, which are demonstrated to be a product of the atomic overlapping of irregular curvatures in the nanotubes. The configuration of some of the experimentally obtained nanotubes is demonstrated to be twisted with a behavior suggesting partial plasticity. PACS 61.16.Bg; 79.60.Jv; 61.46.+w; 61.50.Ah  相似文献   

11.
In this work, the photocatalyst composed of ultrathin MoS2 nanosheets onto the surface of cubic CdS nanoparticles with an average diameter of 7~10 nm has been successfully fabricated through a facile and mild photodeposition route. The ultrathin MoS2 nanosheets as a cocatalyst were demonstrated to greatly boost photocatalytic H2 evolution over cubic CdS upon visible light irradiation. It was clearly revealed that both the cubic CdS substrate and structure of ultrathin MoS2 nanosheets play critical roles in the observed efficient H2 evolution. The cubic CdS offers a strong adherence for ultrathin MoS2 nanosheets to form a well contact interface, across which the photogenerated charge transfer and charge separation are achieved. The ultrathin MoS2 nanosheets introduce a high density of unsaturated active S atoms for H2 evolution.  相似文献   

12.
Embedding alkali-metal in monolayer MoS2 has been investigated by using first principles with density functional theory. The calculation of the electronic and optical properties indicates that alkali-metal was embedded in monolayer MoS2 appearing almost metallic behavior, and the MoS2 layer shows clear p-type doping behavior. The covalent bonding appears between the alkali-metal atoms and defective MoS2. More importantly, embedding alkali-metal can increase the work function for monolayer MoS2. Furthermore, the absorption spectrum of monolayer MoS2 is red shifted because of alkali metal embedding. Accordingly, this study will provide the theoretical basis for producing the alkali-metal-doped monolayer MoS2 radiation shielding and photoelectric devices.  相似文献   

13.
The time dependences of polarization of K0.88(NH4)0.12H2PO4 mixed crystal have been studied within the temperature range of 74–100 K. Two mechanisms of polarization relaxation were found. The first mechanism is caused by domain walls lateral motion and their interaction with point lattice defects. The second one supposedly is due to polar regions infiltration through the regions of frustrated paraelectric phase.  相似文献   

14.
New heterophase superlattices based on MoS2 are studied in detail by the electron density functional theory. It is shown that the incorporation of the 1Т phase in the 2H-MoS2 monolayer is responsible for the formation of electronic levels near the Fermi level and quantum wells in the transverse direction of superlattices. The proposed lateral heterophase structures of transition metal dichalcogenides are promising for the construction of new elements of nanoelectronics.  相似文献   

15.
The electrical properties of a lithium heptagermanate (Li2Ge7O15) crystal have been studied in DC and AC measuring fields at temperatures from 500 to 700 K. In a DC field, a substantial decrease of electrical conductivity σ with time has been detected. On the basis of kinetic dependences σ(t), estimates of the charge carrier diffusion coefficient D have been obtained. In the frequency range 101–105 Hz, the spectra of complex impedance ρ*(f) have been measured. The analysis of diagrams in the complex plane (ρ″–ρ′) has been performed within the equivalent circuit approach. It has been shown that, in the considered temperature and frequency intervals, the electrical properties of Li2Ge7O15 crystals have been determined by the hopping conduction of interstitial lithium ions A Li and accumulation of charge carriers near the blocking Pt electrodes.  相似文献   

16.
17.
Two sets of samples of SnO2/In2O3/TiO2 system have been fabricated with different concentrations of component materials. In the first set TiO2 with rutile structure was used, while in the second set it has the structure of anatase. Thin films (up to 50 nm) of obtained mixtures were deposited. Their sensitivity and selectivity with respect to methane (CH4) were studied. Nanostructure on the basis of 70%SnO2 — 10%In2O3 — 20%TiO2(anatase) exhibits sufficient sensitivity to methane.  相似文献   

18.
The dielectric nonlinearity in BaBi2Nb2O9 and SrBi2Ta2O9 layered ceramics was studied by measuring their polarization loops and reverse dependences of permittivity. It was shown that the features of the dielectric response of BaBi2Nb2O9 and SrBi2Ta2O9 in strong fields can be explained by glass-like properties and the contribution of the domain structure of the ferroelectric material to repolarization processes, respectively.  相似文献   

19.
It is theoretically shown that the Coulomb interaction between violations of the Bernal–Fowler rules leads to a temperature-induced stepwise increase in their concentration by 6–7 orders of magnitude. This first-order phase transition is accompanied by commensurable decrease in the relaxation time and can be interpreted as melting of the hydrogen bond network. The new phase with the melted hydrogen lattice and survived oxygen one is unstable in the bulk of ice, and further drastic increase in the concentrations of oxygen interstitials and vacancies accomplishes the ice melting. The fraction of broken hydrogen bonds immediately after the melting is about 0.07 of their total number that implies an essential conservation of oxygen lattice in water.  相似文献   

20.
Owing to outstandingly tunable optoelectronic properties, hybrid materials consisting of atomic scale thickness of two dimensional (2D) transition metal dichalcogenides (TMDs) and one dimensional (1D) nanowires have been attracting steady interests over the last several years. In this research for the first time we report optically probing the interaction between monolayer MoS2 and single-wall carbon nanotube (SWCNT). By using Raman and photoluminescence measurements, we found the charge transfer between MoS2 and SWCNT is sensitive to the intensity of light field. We also demonstrate that SWCNT acts as p-type dopants at physical contact with monolayer MoS2. Our study gives new insight into the interaction between monolayer MoS2 and SWCNT, which may allow new phenomena and ideas for novel low dimensional hybrid materials.  相似文献   

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