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 MoS ₂ 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.