Structural characterization of GO and rGO. (A) SEM image of GO and rGO enabled by DLW at a laser power of 16 mW; (B) an AFM image and line profile of rGO and GO edges; (C) Raman spectra obtained from the GO film before and after the laser reduction for different laser powers; (D) the C 1s peak from the XPS spectrum of the GO sample; (E) the C 1s peak from the XPS spectrum of the rGO sample.