Identification of monolayers and stacking sequences in 2D - - PowerPoint PPT Presentation

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Identification of monolayers and stacking sequences in 2D - - PowerPoint PPT Presentation

Jan 20, 2023 208 likes •341 views

Identification of monolayers and stacking sequences in 2D nanostructures Aleksey Shmeliov, Anuj Pokle, Quentin Ramasse, Valeria Nicolosi Trinity College Dublin Contents: 1. Introduction 2. 2D MoS 2 /WS 2 3. Black Phosphorous 4. Conclusions

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SLIDE 1

Identification of monolayers and stacking sequences in 2D nanostructures

Aleksey Shmeliov, Anuj Pokle, Quentin Ramasse, Valeria Nicolosi Trinity College Dublin

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SLIDE 2

Contents:

  • 1. Introduction
  • 2. 2D MoS2/WS2
  • 3. Black Phosphorous
  • 4. Conclusions
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SLIDE 3

2D-nanostructures

In principle, any material with a layered structure can form 2D nanocrystals!  Large range of materials:

1. Graphite, hBN, SnS2 2. Transition Metal Chalcogenides 3. Transition Metal Oxides

 All possible electronic properties:

1. Metals (NbSe2) 2. Semi-metals (graphene) 3. Semiconductors (WS2, MoS2) 4. Insulators (MnO2) 5. Superconductors (TaS2) 6. Charge-density waves (NbSe2)

 Potential Applications:

  • 1. Nanocomposites
  • 2. Solar Cells
  • 3. Photocatalysts
  • 4. Batteries
  • 5. Supercapacitors
  • V. Nicolosi et al. “Liquid Exfoliation of Layered Materials,” Science, vol. 340, 2013
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Production of 2D-nanostructures

 Micromechanical cleavage  Chemical Vapour Deposition  Liquid Phase Exfoliation:

  • 1. via intercalated intermediate
  • 2. via addition of surfactants
  • 3. directly in solvent

Stability of dispersions is achieved by matching surface energy of the 2D nanocrystal with the surface energy of the solvent!

J.N. Coleman et al. “Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials,” Science, vol. 331, 2011, pp. 568-571

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Mo/WS2 structure

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ADF STEM of MoS2

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ADF STEM of MoS2

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Non-bulk stacking

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Black Phosphorous

monolayer bilayer trilayer monolayer bilayer trilayer

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Black Phosphorous

R

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Black Phosphorous

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Conclusions

 Monolayers can be readily identified with ADF STEM  2D nanostructures do not necessarily have stacking of the bulk counterparts  So far no-one published atomically resolved image

  • f

phosporene

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ACKNOWLEDGEMENTS

Quentin Ramasse

Mervyn Shannon Valeria Nicolosi Anuj Pokle Peter Nellist Peng Wang Haibo E