Production of mono- to few-layer MoS nanosheets in isopropanol by a salt-assisted direct liquid-phase exfoliation method.

Here, we report a facile salt-assisted direct liquid-phase exfoliation method for mass production of MoS nanosheets. We choose organic solvent isopropanol (IPA) as exfoliation media and potassium ferrocyanide, potassium sodium tartrate, or sodium tartrate as salt, the assistant. The selected salts show universal and efficient assistant effect for the exfoliation of MoS in IPA. Especially, potassium ferrocyanide (KFe(CN)) can enhance the exfoliation efficiency up to 73 times and a dispersion of MoS nanosheets with concentration as high as 0.240 mg mL can be easily obtained in IPA-KFe(CN) system. Transmission electron microscopy, atomic force microscopy (AFM), and Raman spectroscopy show that bulk MoS has been successfully exfoliated into mono- to few-layer MoS nanosheets. AFM analysis indicates that nearly 60% flakes are monolayer in MoS dispersion.