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Journal ArticleDOI

Horizontal growth of MoS2 nanowires by chemical vapour deposition

11 Aug 2015-RSC Advances (The Royal Society of Chemistry)-Vol. 5, Iss: 84, pp 68283-68286
TL;DR: In this article, a single step route for the synthesis of MoS2 wires using a chemical vapour deposition (CVD) method was described, and the horizontally oriented MoS 2 nanowires on SiO2/Si substrate can be synthesized successfully.
Abstract: We describe a single step route for the synthesis of MoS2 wires using a chemical vapour deposition (CVD) method. By tuning the CVD growth parameters, the horizontally oriented MoS2 nanowires on SiO2/Si substrate can be synthesized successfully. The MoS2 nanowire has height of about 93 nm and width of about 402 nm with multilayer structure. Good local photoluminescence (PL) properties can be observed for these horizontal MoS2 nanowires. The successful fabrication and prominent PL effect of the horizontal MoS2 nanowires provide potential applications for the MoS2-based in planar devices.
Citations
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Journal ArticleDOI
TL;DR: By employment of an external vertical magnetic field, ferromagnetic bowl-like MoS2 flake can afford electrons transmitting easily from glassy carbon electrode to active sites to drive HER, and thus perform magnetic HER enhancement.
Abstract: Numerous efforts in improving the hydrogen evolution reaction (HER) performance of transition metal dichalcogenides mostly focus on active sites exposing, vacancy engineering, and phase engineering...

103 citations

Journal ArticleDOI
TL;DR: In this paper, a high-performance NO2 sensor based on a one dimensional MoS2 nanowire (NW) network was synthesized using chemical transport reaction through controlled turbulent vapor flow.
Abstract: We report on a high-performance NO2 sensor based on a one dimensional MoS2 nanowire (NW) network The MoS2 NW network was synthesized using chemical transport reaction through controlled turbulent vapor flow The crystal structure and surface morphology of MoS2 NWs were confirmed by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy Further, the sensing behavior of the nanowires was investigated at different temperatures for various concentrations of NO2 and the sensor exhibited about 2-fold enhanced sensitivity with a low detection limit of 46 ppb for NO2 at 60 °C compared to sensitivity at room temperature Moreover, it showed a fast response (16 s) with complete recovery (172 s) at 60 °C, while sensitivity of the device was decreased at 120 °C The efficient sensing with reliable selectivity toward NO2 of the nanowires is attributed to a combination of abundant active edge sites along with a large surface area and tuning of the potential barrier

83 citations

Journal ArticleDOI
TL;DR: In this paper, a uniform coverage of MoS2 HNPs with a thickness around 20 nm is achieved by chemical vapor deposition technique, and the results confirm that the CNT template plays an important role in the growth of the HNP.
Abstract: Hexagonal-shaped nanoplates (HNPs) of MoS2 on vertically aligned carbon nanotubes (CNTs) over a patterned area (a circular area of 1 cm2 diameter) are produced by chemical vapor deposition technique With an optimized initial Mo film thickness, a uniform coverage of MoS2 HNPs with a thickness around 20 nm is achieved The results confirm that the CNT template plays an important role in the MoS2 HNPs growth Each MoS2 HNP consists of abundant exposed edges, interesting for sensing and catalysis applications High crystallinity and quality of the as-produced material are revealed by X-ray photoelectron and Raman spectroscopies Furthermore, NO2 gas-sensing studies show better sensitivity and recovery for MoS2/CNT samples as compared to pristine CNTs The detection of NO2 gas in a few tens of parts per million to a few hundreds of parts per billion range, at room temperature, is achieved Density-functional theory calculation indicates that the exposed edges of MoS2 play a significant role in the NO2 sensing as compared to horizontally aligned MoS2 layers The present report can promote the research toward the fabrication of efficient and reliable MoS2-based hybrid materials for toxic gas-sensing applications for air quality monitoring in various environments

73 citations

Journal ArticleDOI
TL;DR: In this paper, the potential of resistive memory devices in resistive memories has been investigated using crystallographically controlled synthesis of SnSe nanowires, which has been published in final form at 10.1002/admi.202000474.
Abstract: Rights © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. This is the peer reviewed version of the following article: ‘Crystallographically Controlled Synthesis of SnSe Nanowires: Potential in Resistive Memory Devices’, Adv. Mater. Interfaces 2020, 2000474, which has been published in final form at 10.1002/admi.202000474. This article may be used for noncommercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

58 citations

Journal ArticleDOI
TL;DR: The as-grown MoS2 NSs would be highly useful in the development of catalysis, nano-optoelectronics, gas-sensing and bio-sensor applications, and the high crystallinity and quality of the synthesized NSs are revealed.
Abstract: Vertically aligned MoS2 nanosheets (NSs) with exposed edges were successfully synthesized over a large area (∼2 cm2). The NSs were grown using an ambient pressure chemical vapor deposition technique via rapid sulfurization of sputter deposited thick molybdenum films. Extensive characterization of the grown MoS2 NSs has been carried out using high resolution scanning and transmission electron microscopy (SEM & TEM). A special care was given to the TEM lamella preparation process by means of a focused ion beam to preserve the NS growth direction. The cross-section TEM measurements revealed the growth of densely packed, vertically aligned and straight MoS2 NSs. Additional characterization techniques such as atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and photoluminescence (PL) were used to evaluate the MoS2 NSs. These studies revealed the high crystallinity and quality of the synthesized NSs. The MoS2 NSs show visible light emission similar to mechanically exfoliated monolayer MoS2 NSs. The striking PL signal comes from the exposed edges as shown by experimental and theoretical calculations. The vertical MoS2 NSs also exhibit a hydrophobic character with a contact angle of 114°. The as-grown MoS2 NSs would be highly useful in the development of catalysis, nano-optoelectronics, gas-sensing and bio-sensing device applications.

49 citations

References
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Journal ArticleDOI
TL;DR: Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors, and could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.
Abstract: Two-dimensional materials are attractive for use in next-generation nanoelectronic devices because, compared to one-dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two-dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16), previously reported mobilities in the 0.5-3 cm(2) V(-1) s(-1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room-temperature single-layer MoS(2) mobility of at least 200 cm(2) V(-1) s(-1), similar to that of graphene nanoribbons, and demonstrate transistors with room-temperature current on/off ratios of 1 × 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.

12,477 citations

Journal ArticleDOI
TL;DR: This Review describes how the tunable electronic structure of TMDs makes them attractive for a variety of applications, as well as electrically active materials in opto-electronics.
Abstract: Ultrathin two-dimensional nanosheets of layered transition metal dichalcogenides (TMDs) are fundamentally and technologically intriguing. In contrast to the graphene sheet, they are chemically versatile. Mono- or few-layered TMDs - obtained either through exfoliation of bulk materials or bottom-up syntheses - are direct-gap semiconductors whose bandgap energy, as well as carrier type (n- or p-type), varies between compounds depending on their composition, structure and dimensionality. In this Review, we describe how the tunable electronic structure of TMDs makes them attractive for a variety of applications. They have been investigated as chemically active electrocatalysts for hydrogen evolution and hydrosulfurization, as well as electrically active materials in opto-electronics. Their morphologies and properties are also useful for energy storage applications such as electrodes for Li-ion batteries and supercapacitors.

7,903 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that only the Raman frequencies of E 1 and A 1g peaks vary monotonously with the layer number of ultrathin Molybdenum disulfi de (MoS 2 ).
Abstract: Molybdenum disulfi de (MoS 2 ) is systematically studied using Raman spectroscopy with ultraviolet and visible laser lines. It is shown that only the Raman frequencies of E 1 and A1g peaks vary monotonously with the layer number of ultrathin MoS 2 fl akes, while intensities or widths of the peaks vary arbitrarily. The coupling between electronic transitions and phonons are found to become weaker when the layer number of MoS 2 decreases, attributed to the increased electronic transition energies or elongated intralayer atomic bonds in ultrathin MoS 2 . The asymmetric Raman peak at 454 cm − 1 , which has been regarded as the overtone of longitudinal optical M phonons in bulk MoS 2 , is actually a combinational band involving a longitudinal acoustic mode (LA(M)) and an optical mode ( A2u ). Our fi ndings suggest a clear evolution of the coupling between electronic transition and phonon when MoS 2 is scaled down from three- to two-dimensional geometry.

3,375 citations

Journal ArticleDOI
TL;DR: EMS as mentioned in this paper is a set of computer programs which have been developed not only for the simulation and analysis of high-resolution Electron Microscopy images, but also for the analysis of diffraction patterns.

1,897 citations

Journal ArticleDOI
20 May 2014-ACS Nano
TL;DR: The results provide a new route for modulating the optical properties of two-dimensional semiconductors and the strong and stable PL from defects sites of MoS2 may have promising applications in optoelectronic devices.
Abstract: We report on a strong photoluminescence (PL) enhancement of monolayer MoS2 through defect engineering and oxygen bonding. Micro-PL and Raman images clearly reveal that the PL enhancement occurs at cracks/defects formed during high-temperature annealing. The PL enhancement at crack/defect sites could be as high as thousands of times after considering the laser spot size. The main reasons of such huge PL enhancement include the following: (1) the oxygen chemical adsorption induced heavy p doping and the conversion from trion to exciton; (2) the suppression of nonradiative recombination of excitons at defect sites, which was verified by low-temperature PL measurements. First-principle calculations reveal a strong binding energy of ∼2.395 eV for an oxygen molecule adsorbed on a S vacancy of MoS2. The chemically adsorbed oxygen also provides a much more effective charge transfer (0.997 electrons per O2) compared to physically adsorbed oxygen on an ideal MoS2 surface. We also demonstrate that the defect enginee...

953 citations