Excitation-dependent photoluminescence from WS2 nanostructures synthesized via top-down approach

Sharma, Satinder K.; Bhagat, Shubham; Singh, Jasvir; Singh, Ravi Chand; Sharma, Sandeep

doi:10.1007/s10853-017-1303-3

Cited by 73 publications

(51 citation statements)

References 40 publications

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“…This is contrary to what has been noticed for scaled TiS 2 sheet [27] with only one, two, four and five layers. These results also differ from Raman spectra obtained from scaled nanostructures of WS 2 and MoS 2 where A 1g and E 1 2g modes soften [36,37]. Therefore, the observed shift in A1g mode might arise from scaled nanostructures.…”

Section: Resultscontrasting

confidence: 79%

Structural transformation and room temperature ammonia sensing properties of TiS2 nanostructures

Sharma

Singh

et al. 2020

SN Appl. Sci.

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The nanostructures of TiS 2 have been successfully synthesized in a single-step process using probe sonication in various liquid media. Initial visual inspection confirmed that the nanostructures prepared in de-ionized water and de-ionized water-ethanol mixture change color from black to white with time. Various structural, optical and vibrational measurements identified these changes due to structural transformation of TiS 2 into TiO 2 in presence of water molecules. However, this transformation was absent in TiS 2 nanostructures prepared in media like di-methyle formamide and N-methyle pyrolidone. These nanostructures were used for making two terminal sensor devices and yielded entirely different results. The black colored TiS 2 showed highly selective n-type behaviour towards ammonia (200 ppm) with nearly 72% relative response at room temperature. Corresponding rise time and recovery time were found to be 72 ± 7 s and 165 ± 10 s, respectively. Contrary to this, the other device made from white powder did not show a detectable change in base resistance of the sensor. These initial results indicate the potential use of stable TiS 2 nanostructures as a highly selective and sensitive room temperature ammonia sensor.

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Section: Resultscontrasting

confidence: 79%

Structural transformation and room temperature ammonia sensing properties of TiS2 nanostructures

Sharma

Singh

et al. 2020

SN Appl. Sci.

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“…The pristine WS2 exhibited multiple diffraction peaks by the phase matching for different principal planes (JCPDS #08-0237). It was also observed that the intensive peak of the (002) plane occurred at 14.28 degrees, followed by (004), (006), and (008) planes at 28.81, 43.92, and 59.73 degrees, respectively, which is attributed to the layered nature of the WS2 flakes [21,22]. After sintering, the whole samples maintained the characteristic peaks from WS2, The crystal characteristics of the sintered WS 2 and WS 2 /SWCNH nanocomposites were confirmed by XRD patterns, as shown in Figure 5b.…”

Section: Resultsmentioning

confidence: 88%

Enhanced Thermoelectric Properties of WS2/Single-Walled Carbon Nanohorn Nanocomposites

Kim

Lee

et al. 2020

Crystals

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Recently, two-dimensional tungsten disulfide (WS2) has attracted attention as a next generation thermoelectric material due to a favorable Seebeck coefficient. However, its thermoelectric efficiency still needs to be improved due to the intrinsically low electrical conductivity of WS2. In the present study, thermoelectric properties of WS2 hybridized with highly conductive single-walled carbon nanohorns (SWCNHs) were investigated. The WS2/SWCNH nanocomposites were fabricated by annealing the mixture of WS2 and SWCNHs using a high-frequency induction heated sintering (HFIHS) system. By adding SWCNHs to WS2, the nanocomposites exhibited increased electrical conductivity and a slightly decreased Seebeck coefficient with the content of SWCNHs. Hence, the maximum power factor of 128.41 μW/mK2 was achieved for WS2/SWCNHs with 0.1 wt.% SWCNHs at 780 K, resulting in a significantly improved thermoelectric figure of merit (zT) value of 0.027 compared to that of pristine WS2 with zT 0.017.

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“…Our findings are consistent with previous reports in the literature, and further confirm the vertical orientation of the WS2 nanosheets. 24,25,26,27,28 Furthermore, by comparing the Raman spectra of the out-of-plane WS2 crosssection with the one obtained from the corresponding bulk specimen (Figure 4b) one…”

Section: Figure 4amentioning

confidence: 99%

“…These differences could be related to the fact that our vertical WS2 and MoS2 bulk specimens are scaled down in a different way for the fabrication of the out-of-plane and in-plane cross-sections. 25 In the case of the out-ofplane WS2, we scale down along a single direction, similarly to what happens in the exfoliated process. While in the case of the in-plane MoS2 specimen, all three spatial directions are being reduced simultaneously.…”

Section: Figure 4amentioning

confidence: 99%

Robust Sample Preparation of Large-Area In- and Out-of-Plane Cross Sections of Layered Materials with Ultramicrotomy

Cichocka

Bolhuis

Heijst

et al. 2020

ACS Appl. Mater. Interfaces

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Layered materials (LMs) such as graphene or MoS2 have recently attracted a great deal of interest. These materials offer unique functionalities due to their structural anisotropy characterized by weak van der Waals bonds along the out-of-plane axis and covalent bonds in the in-plane direction. A central requirement to access the structural information of complex nanostructures built upon LMs is to control the relative orientation of each sample prior to their inspection e.g. with Transmission Electron Microscopy (TEM). However, developing sample preparation methods that result in large inspection areas and ensure full control over the sample orientation while avoiding damage during the transfer to the TEM grid is challenging.Here we demonstrate the feasibility of deploying ultramicrotomy for the preparation of LM samples in TEM analyses. We show how ultramicrotomy leads to the reproducible large-scale production of both in-plane and out-of-plane cross-sections, with bulk vertically-oriented MoS2 and WS2 nanosheets as proof of concept. The robustness of the prepared samples is subsequently verified by their characterization by means of both high-resolution TEM and Raman spectroscopy measurements. Our approach is fully general and should find applications for a wide range of materials as well as of techniques beyond TEM, thus paving the way to the systematic large-area mass-production of cross-sectional specimens for structural and compositional studies.

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Excitation-dependent photoluminescence from WS2 nanostructures synthesized via top-down approach

Cited by 73 publications

References 40 publications

Structural transformation and room temperature ammonia sensing properties of TiS2 nanostructures

Structural transformation and room temperature ammonia sensing properties of TiS2 nanostructures

Enhanced Thermoelectric Properties of WS2/Single-Walled Carbon Nanohorn Nanocomposites

Robust Sample Preparation of Large-Area In- and Out-of-Plane Cross Sections of Layered Materials with Ultramicrotomy

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