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Title: Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers

Abstract

Exfoliation of large-area monolayers is important for fundamental research and technological implementation of transitionmetal dichalcogenides. Various techniques have been explored to increase the exfoliation yield, but little is known about the underlying mechanism at the atomic level. Here, we demonstrate gold-assisted mechanical exfoliation of monolayer molybdenum disulfide, up to a centimeter scale. Detailed spectroscopic, microscopic, and firstprinciples density functional theory analyses reveal that strong van der Waals (vdW) interaction between Au and the topmost MoS 2 layer facilitates the exfoliation of monolayers. However, the large-area exfoliation promoted by such strong vdW interaction is only achievable on freshly prepared clean and smooth Au surfaces, while rough surfaces and surfaces exposed to air for more than 15 min result in negligible exfoliation yields. This technique is successfully extended to MoSe 2, WS 2, WSe 2, MoTe 2, WTe 2, and GaSe. In addition, electrochemical characterization reveals intriguing interactions between monolayer MoS 2 and Au. A subnanometer-thick MoS 2 monolayer strongly passivates the chemical properties of the underlying Au, and the Au significantly modulates the electronic band structure of the MoS 2, turning it from semiconducting to metallic. This could find applications in many areas, including electrochemistry, photovoltaics, and photocatalysis

Authors:
 [1];  [2];  [2];  [2];  [2];  [3];  [4]; ORCiD logo [5]; ORCiD logo [6]; ORCiD logo [3];  [7];  [8]; ORCiD logo [3];  [2];  [2]; ORCiD logo [2]
  1. Queen’s Univ. Belfast, Belfast, Ireland (United Kingdom). School of Mathematics and Physics; Univ. of Manchester (United Kingdom). School of Physics and Astronomy; Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry and Chemical Biology
  2. Queen’s Univ. Belfast, Belfast, Ireland (United Kingdom). School of Mathematics and Physics
  3. Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry and Chemical Biology
  4. Cornell Univ., Ithaca, NY (United States). Dept. of Material Science and Engineering
  5. Cornell Univ., Ithaca, NY (United States). School of Applied and Engineering Physics
  6. National Physical Lab., Teddington (United States)
  7. Cornell Univ., Ithaca, NY (United States). School of Applied and Engineering Physics, and Kavli Inst. at Cornell for Nanoscale Science
  8. Univ. of Manchester (United Kingdom). School of Physics and Astronomy
Publication Date:
Research Org.:
Queen’s Univ. Belfast, Belfast, Ireland (United Kingdom)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1478541
Alternate Identifier(s):
OSTI ID: 1508741
Grant/Contract Number:  
FG02-97ER25308
Resource Type:
Journal Article: Published Article
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 10; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; transition-metal dichalcogenide; MoS2; gold; monolayer; exfoliation; electrochemical; mechanism

Citation Formats

Velický, Matěj, Donnelly, Gavin E., Hendren, William R., McFarland, Stephen, Scullion, Declan, DeBenedetti, William J. I., Correa, Gabriela Calinao, Han, Yimo, Wain, Andrew J., Hines, Melissa A., Muller, David A., Novoselov, Kostya S., Abruña, Héctor D., Bowman, Robert M., Santos, Elton J. G., and Huang, Fumin. Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers. United States: N. p., 2018. Web. doi:10.1021/acsnano.8b06101.
Velický, Matěj, Donnelly, Gavin E., Hendren, William R., McFarland, Stephen, Scullion, Declan, DeBenedetti, William J. I., Correa, Gabriela Calinao, Han, Yimo, Wain, Andrew J., Hines, Melissa A., Muller, David A., Novoselov, Kostya S., Abruña, Héctor D., Bowman, Robert M., Santos, Elton J. G., & Huang, Fumin. Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers. United States. doi:10.1021/acsnano.8b06101.
Velický, Matěj, Donnelly, Gavin E., Hendren, William R., McFarland, Stephen, Scullion, Declan, DeBenedetti, William J. I., Correa, Gabriela Calinao, Han, Yimo, Wain, Andrew J., Hines, Melissa A., Muller, David A., Novoselov, Kostya S., Abruña, Héctor D., Bowman, Robert M., Santos, Elton J. G., and Huang, Fumin. Fri . "Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers". United States. doi:10.1021/acsnano.8b06101.
@article{osti_1478541,
title = {Mechanism of Gold-Assisted Exfoliation of Centimeter-Sized Transition-Metal Dichalcogenide Monolayers},
author = {Velický, Matěj and Donnelly, Gavin E. and Hendren, William R. and McFarland, Stephen and Scullion, Declan and DeBenedetti, William J. I. and Correa, Gabriela Calinao and Han, Yimo and Wain, Andrew J. and Hines, Melissa A. and Muller, David A. and Novoselov, Kostya S. and Abruña, Héctor D. and Bowman, Robert M. and Santos, Elton J. G. and Huang, Fumin},
abstractNote = {Exfoliation of large-area monolayers is important for fundamental research and technological implementation of transitionmetal dichalcogenides. Various techniques have been explored to increase the exfoliation yield, but little is known about the underlying mechanism at the atomic level. Here, we demonstrate gold-assisted mechanical exfoliation of monolayer molybdenum disulfide, up to a centimeter scale. Detailed spectroscopic, microscopic, and firstprinciples density functional theory analyses reveal that strong van der Waals (vdW) interaction between Au and the topmost MoS2 layer facilitates the exfoliation of monolayers. However, the large-area exfoliation promoted by such strong vdW interaction is only achievable on freshly prepared clean and smooth Au surfaces, while rough surfaces and surfaces exposed to air for more than 15 min result in negligible exfoliation yields. This technique is successfully extended to MoSe2, WS2, WSe2, MoTe2, WTe2, and GaSe. In addition, electrochemical characterization reveals intriguing interactions between monolayer MoS2 and Au. A subnanometer-thick MoS2 monolayer strongly passivates the chemical properties of the underlying Au, and the Au significantly modulates the electronic band structure of the MoS2, turning it from semiconducting to metallic. This could find applications in many areas, including electrochemistry, photovoltaics, and photocatalysis},
doi = {10.1021/acsnano.8b06101},
journal = {ACS Nano},
issn = {1936-0851},
number = 10,
volume = 12,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1021/acsnano.8b06101

Citation Metrics:
Cited by: 6 works
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Figures / Tables:

Figure 1 Figure 1: Exfoliation and characterization of MoS2 on Au substrate. (a) Optical macrograph of a large-area monolayer MoS2 on a 7.5 nm Au/ 1 nm Ti/93 nm SiO2/Si wafer. (b) Optical micrograph of a large-area monolayer MoS2. (c) High-resolution optical micrographs of the mono- and multilayer MoS2. (d) Raman spectramore » (532 nm excitation) of mono- and multilayer MoS2 in (c), showing the main in-plane (E2g 1 ) and out-of-plane (A1g) vibrational modes (spectra are offset for clarity). (e) AFM topography image taken from the area highlighted in (c) by the black square, showing a smooth MoS2 surface and tape residue on the Au surface. Inset: the corresponding height profile of monolayer−bilayer boundary, taken from the area highlighted by the white rectangle.« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.