fig4

Figure 4. (A) (i) Schematic diagram of the PVD method^[57]; (ii) AFM height profile of a twin structure nanosheet; (iii) HAADF-STEM image of Se nanosheets; Copyright 2017, American Chemical Society. (B) (i) Schematic of the CVT method^[71]; (ii) Optical microscope image of Se nanoflakes; (iii) AFM image of a Se nanoflake; Copyright 2018, © TÜRKİYE. (C) (i) Schematic demonstration of sonication liquid-phase exfoliation method^[58]; (ii) TEM images of Se nanosheets; (iii) AFM images of Se nanosheets; Copyright 2017, Wiley-VCH.