MoS2, which is similar to graphene in terms of structure, is a layered transition metal dichalcogenide (TMD). Compared to some other TMDs, MoS2 is naturally abundant and relatively cheap and thus has attracted increasing attention . It has been widely investigated for applications in electronics, photonics, sensing, energy storage etc. . Exfoliated MoS2 can be obtained through mechanical exfoliation, liquid phase exfoliation, electrochemical exfoliation, and chemical exfoliation .