High-Concentration Aqueous Dispersions of MoS2

Molybdenum disulfide (MoS2) nanosheets have been attracting increasing research interests due to their unique material properties. However, the lack of a reliable large-scale production method impedes their practical applications. Here a facile, efficient, and scalable method for the fabrication of high-concentration aqueous dispersion of MoS2 nanosheets using combined grinding and sonication is reported. The 26.7 +/- 0.7 mg/mL concentration achieved is the highest concentration in an aqueous solution reported up to now. Grinding generates pure shear forces to detach the MoS2 layers from the bulk materials. Subsequent sonication further breaks larger crystallites into smaller crystallites, which promotes the dispersion of MoS2 nanosheets in ethanol/water solutions. The exfoliation process establishes a new paradigm in the top-down fabrication of 2D nanosheets in aqueous solution. In the meantime, MoS2-based sensing film produced using this approach has successfully demonstrated the feasibility of a low-cost and efficient NH3 gas sensor using inkjet printing as a viable method.