Long-term stability of mechanically exfoliated MoS2 flakes

Budania, Prachi; Baine, Paul; Montgomery, Jenny; McGeough, Conor; Cafolla, Tony; Modreanu, M.; McNeill, David; Mitchell, Neil; Hughes, G.; Hurley, Paul K.

doi:10.1557/mrc.2017.105

Cited by 53 publications

(52 citation statements)

References 23 publications

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“…Having established the likely edge morphology, we can investigate ambient stability of 2H‐TaS 2 nanoparticles by calculating their susceptibility to oxidation. The oxidation is assumed to initiate at the edge, in accordance with recent experimental and theoretical evidence [37,42,43,53–55] . Here, we consider both the one dimensional nanostripe as well as the triangular cluster.…”

Section: Resultsmentioning

confidence: 89%

“…The oxidation is assumed to initiate at the edge, in accordance with recent experimental and theoretical evidence. [37,42,43,[53][54][55] Here, we consider both the one dimensional nanostripe as well as the triangular cluster. For both models, we consider oxidation of the Ta-edge covered by 50 % sulfur atoms, which is found to be the most stable edge in previous section.…”

Section: Oxidation Of 2h-tasmentioning

confidence: 99%

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Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

2020

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Tantalum disulphide belongs to the group of transition metal dichalcogenides (TMDs) and has attracted attention for its unique structural, electronic, and catalytic properties. Herein, we report the edge properties of single-layer 2H-TaS 2 studied by using density functional theory calculations, because the knowledge of the edge morphology, stability, and surface energy is essential for the determination of nanoparticle shapes and understanding the nature of catalytically active sites. We calculate the grand canonical potential of TaS 2 clusters having various edge morphologies to evaluate the edge energies of the Ta-edge and S-edge terminated surfaces. Under S-rich conditions, the most likely shape of TaS 2 is a deformed hexagon dominated by the Ta-edge covered by S monomers, while the triangular shape is preferred under S-poor conditions. Exposed edges of the single-layer TaS 2 are susceptible to oxidation in air because both oxygen adsorption and substitution at the edge are strongly exothermic, À 0.96 and À 2.20 eV for single O atom, respectively. The XPS calculation shows that specific initial steps of oxidative process (adsorption, vacancy creation, substitution) are unlikely to be distinguished in the XPS spectra due to small shift of respective binding energies, but initial edge oxidation of TaS 2 should be observable by an asymmetry of the Ta 4f doublet towards higher binding energies.

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Section: Resultsmentioning

confidence: 89%

Section: Oxidation Of 2h-tasmentioning

confidence: 99%

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

2020

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“…The photo-oxidation of semiconductors is not limited to direct bandgap materials, and has also been reported for silicon (note that CrI3 also has an indirect bandgap), 54 although the effect was found to be less pronounced than for direct bandgap materials. 46 Thus, it is expected that even multilayers of S-TMDs will undergo ambient air photo-oxidation, and indeed this has been reported by Budania et al 52 which observed oxidation in exfoliated multilayer MoS2 samples left in ambient conditions (though the role of light was not investigated). The photoinduced oxidation of semiconductors in ambient atmosphere seems to be a universal effect, yet not much attention has been paid to the mechanism in the 2D community, especially in regard to S-TMDs.…”

Section: Discussionmentioning

confidence: 89%

Oxidation of Monolayer WS₂ in Ambient Is a Photoinduced Process

et al. 2019

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We have studied the ambient air oxidation of chemical vapor deposition (CVD) grown monolayers of the semiconducting transition metal dichalcogenide (S-TMD) WS2 using optical microscopy, laser scanning confocal microscopy (LSCM), photoluminescence (PL) spectroscopy, and atomic force microscopy (AFM). Monolayer WS2 exposed to ambient conditions in the presence of light (typical laboratory ambient light for weeks or typical PL spectroscopy map) exhibits damage due to oxidation which can be detected with the LSCM and AFM, though may not be evident in conventional optical microscopy due to poorer contrast and resolution. Additionally, this oxidation was not random and was correlated with “high-symmetry” high intensity edges and red-shifted areas in the PL spectroscopy map, areas thought to contain a higher concentration of sulfur vacancies. In contrast, samples kept in ambient and darkness showed no signs of oxidation for up to 10 months. Low-irradiance/fluence experiments showed that samples subjected to excitation energies at or above the trion excitation energy (532 nm/2.33 eV and 660 nm/1.88 eV) oxidized in as little as 7 days, even for irradiances and fluences 8 and 4 orders of magnitude lower (respectively) than previously reported. No significant oxidation was observed for 760 nm/1.63 eV light exposure, which lies below the trion excitation energy in WS2. The strong wavelength dependence and apparent lack of irradiance dependence suggests that ambient oxidation of WS2 is initiated by photon-mediated electronic band transitions, that is, photo-oxidation. These findings have important implications for prior, present, and future studies concerning S-TMDs measured, stored, or manipulated in ambient conditions.

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“…The environmental stability is another important property of 2D materials. For many 2D materials, such as BP [19,21,[96][97][98] and TMDCs [99][100][101][102], instability has severely hindered their further development in both academic and industrial applications. In sharp contrast, extraordinary environmental stability has been demonstrated for various thicknesses of 2D Te (ranging from few-layer to monolayer).…”

Section: Stabilitymentioning

confidence: 99%

Two-Dimensional Tellurium: Progress, Challenges, and Prospects

Shi¹,

Cao²,

Khan³

et al. 2020

Nano-Micro Lett.

185

127

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HIGHLIGHTS • Physical Properties of the two-dimensional tellurium were discussed in detail, including electrical properties, optical properties, thermoelectric properties, and outstanding environmental stability. • Emerging applications based on atomically thin tellurene flakes were presented, such as photodetector, transistors, piezoelectric device, modulator, and energy harvesting devices. • The challenges encountered and prospects were presented.

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Long-term stability of mechanically exfoliated MoS2 flakes

Abstract: Abstract

Cited by 53 publications

References 23 publications

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

Oxidation of Monolayer WS₂ in Ambient Is a Photoinduced Process

Two-Dimensional Tellurium: Progress, Challenges, and Prospects

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Long-term stability of mechanically exfoliated MoS2 flakes

Abstract: Abstract

Cited by 53 publications

References 23 publications

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS2

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS2

Oxidation of Monolayer WS2 in Ambient Is a Photoinduced Process

Two-Dimensional Tellurium: Progress, Challenges, and Prospects

Contact Info

Product

Resources

About

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

Atomic‐Scale Edge Morphology, Stability, and Oxidation of Single‐Layer 2H‐TaS₂

Oxidation of Monolayer WS₂ in Ambient Is a Photoinduced Process