Large-scale production of two-dimensional nanosheets

Two-dimensional (2D) nanomaterials such as graphene, boron nitride (BN), and molybdenum disulfide (MoS2) have been attracting increasing research interest in the past few years due to their unique material properties. However, the lack of a reliable large-scale production method is an inhibiting issue for their practical applications. Here we report a facile, efficient, and scalable method for the fabrication of monolayer and few-layer BN, MoS2, and graphene using combined low-energy ball milling and sonication. Ball milling generates two forces on layered materials, shear force and compression force, which can cleave layered materials into 2D nanosheets from the top/bottom surfaces, and the edge of layered materials. Subsequent sonication would further break larger crystallites into smaller crystallites. These fabricated 2D nanosheets can be well dispersed in aqueous solutions at high concentrations, 1.2 mg mL−1 for BN, 0.8 mg mL−1 for MoS2, and 0.9 mg mL−1 for graphene, which are highly advantageous over other methods. These advantages render great potential in the construction of high-performance 2D material-based devices at low cost. For example, a prototype gas sensor is demonstrated in our study using graphene and MoS2, respectively, which can detect several ppm of ammonia gas.