Fig. 3: Characterization of GO and preparation process of coatings.

a The cross-section fracture morphology of the GO film. The SEM and digital photographs of the surface of the GO film are in the illustration. b AFM of the prepared GO and the corresponding height map of the selected area. c Absorbance of the GO aqueous dispersion. d The whole preparation route of coatings. The illustrations were respectively bulk Gr, GO, and the WPU-GO film on white paper, and the OM pictures of WPU and WPU-GOLM coating.