Figure 4

Mechanical and liquid exfoliation method. (a) Optical image of graphene, MoS₂, NbSe₂, and h-BN flakes prepared by mechanical exfoliation method. The red dotted squares represent the subsequent AFM scan areas [45]. (b) AFM friction images measured simultaneously by AFM from the indicated areas in the red dotted squares. S indicates SiO₂ substrate [45]. (c) Photographs of dispersions of MoS₂ (in NMP), WS₂ (in NMP), and BN (in IPA) [59]. (d)-(f) Low resolution TEM images of BN, MoS₂, and WS₂ nanosheets prepared by liquid exfoliation method [59].