Large-scale production of defect-free MoS2 nanosheets via pyrene-assisted liquid exfoliation

Two dimensional (2D) layered MoS2 nanosheets are gaining increasing attention due to their attractive properties associated with myriads potential applications. However, large-scale production of highquality MoS2 nanosheets in a simple manner remains a big challenge. Herein, we present a facile approach for scalable production of defect-free MoS2 nanosheets by direct ultrasonication exfoliation of bulk MoS2 crystals in ethanol in the presence of pyrene. Our findings indicate that the pyrene can not only serve as an exfoliating agent to significantly accelerate the exfoliation process but also endow the resulted MoS2 nanosheets with excellent solution dispersibility and stability. The obtained MoS2 nanosheets are highly crystalline and exhibit superior electrical properties as compared with the bulk MoS2. In addition, the MoS2 nanosheets can also be employed as nanofillers to enhance the mechanical properties of polymers. Moreover, this method can also be extended to exfoliation of other 2D layered transition metal dichalcogenide as demonstrated by the exfoliation of bulk WS2 crystals in this study. This work thus brings more opportunities for the investigation and applications of 2D layered inorganic nanosheets. (C) 2017 Elsevier B.V. All rights reserved.