Fig. 10.

a Schematic illustration of one of the top-down synthesis approach (thermal polymerization) for g-C₃N₄ using different precursors. Black balls—carbon (C), blue balls—nitrogen (N), white balls—hydrogen (H), red balls—oxygen (O), and yellow balls—sulfur (S), respectively. Reproduced with permission from Ref. [84]. b Schematic of the synthesis of g-C₃N₄ nanosheets from bulk g-C₃N₄. In the atomic model, carbon atoms—gray balls, nitrogen atoms—blue balls and hydrogen atoms—red. c TEM image of g-C₃N₄ nanosheets. d Tapping-mode AFM image of a single g-C₃N₄ nanosheet deposited on the silicon wafer substrate. The inset is the height curve determined along the line between P1 and P4. Reproduced with permission from Ref. [88]. Copyright permissions from American Chemical Society and Wiley–VCH. (Color figure online)