Fig. 2

Raman spectra of graphene-based samples under study. Raman spectra of the different graphene samples on glass a and different substrates b performed using a 532-nm laser excitation system with a ×40 microscope objective, and 10 s integration time for a single scan. c shows the splitting of the G peak into 3 peaks in a i-FLG sample. As previously reported, the Raman shift of G to G0, G1 and G2 stem for a graphene sheet with randomly distributed FeCl₃ molecules, one or two adjacent FeCl₃ layers as shown by the schematic crystal structure