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Article

High yield exfoliation of two-dimensional chalcogenides using sodium naphthalenide

  • Nature Communications 5, Article number: 2995 (2014)
  • doi:10.1038/ncomms3995
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Abstract

Transition-metal dichalcogenides like molybdenum disulphide have attracted great interest as two-dimensional materials beyond graphene due to their unique electronic and optical properties. Solution-phase processes can be a viable method for producing printable single-layer chalcogenides. Molybdenum disulphide can be exfoliated into monolayer flakes using organolithium reduction chemistry; unfortunately, the method is hampered by low yield, submicron flake size and long lithiation time. Here we report a high-yield exfoliation process using lithium, potassium and sodium naphthalenide where an intermediate ternary LixMXn crystalline phase (X=selenium, sulphur, and so on) is produced. Using a two-step expansion and intercalation method, we produce high-quality single-layer molybdenum disulphide sheets with unprecedentedly large flake size, that is up to 400 μm2. Single-layer dichalcogenide inks prepared by this method may be directly inkjet-printed on a wide range of substrates.

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Acknowledgements

K.P.L. is grateful for the MOE Tier 1 grant ‘Two dimensional crystals as platforms for optoelectronics (R-143-000-556-112)’ and also NRF-CRP project ‘Novel 2D materials with tailored properties beyond graphene (R-144-000-295-281)’. H.S.S. is grateful for a grant (code no. 2011-0031630) from the Center for Advanced Soft Electronics under the Global Frontier Research Program through the National Research Foundation funded by the Ministry of Science, ICT and Future Planning, Korea.

Author information

Affiliations

  1. Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore

    • Jian Zheng
    • , Han Zhang
    • , Shaohua Dong
    • , Yanpeng Liu
    • , Chang Tai Nai
    • , Bo Liu
    •  & Kian Ping Loh
  2. Interdisciplinary School of Green Energy and Low Dimensional Carbon Materials Center, UNIST Central Research Facilities (UCRF), Ulsan National Institute of Science and Technology (UNIST), UNIST-gil 50, Ulsan 689-805, Korea

    • Hyeon Suk Shin
    •  & Hu Young Jeong

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Contributions

J.Z. designed the work and performed the experiments. K.P.L. conceptualized the work, analysed the data and wrote the paper. H.Z., S.D., Y.P.L., C.T.N., H.S.S., H.Y.J. and B.L. performed some characterization experiments and analysed data.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Kian Ping Loh.

Supplementary information

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  1. 1.

    Supplementary Information

    Supplementary Figures S1-S17, Supplementary Notes 1-3 and Supplementary References

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