High yield exfoliation of two-dimensional chalcogenides using sodium naphthalenide.
Jian Zheng, Han Zhang, Shaohua Dong, Yanpeng Liu, Chang Tai Nai, Hyeon Suk Shin, Hu Young Jeong, Bo Liu, Kian Ping Loh
Author Information
Jian Zheng: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Han Zhang: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Shaohua Dong: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Yanpeng Liu: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Chang Tai Nai: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Hyeon Suk Shin: 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.
Hu Young Jeong: 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.
Bo Liu: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
Kian Ping Loh: Department of Chemistry and Graphene Research Centre, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
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 Li(x)MX(n) 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 μm(2). Single-layer dichalcogenide inks prepared by this method may be directly inkjet-printed on a wide range of substrates.
