Fig. 2: Morphology and structure characterizations of cg-G.

a Photograph of a cuboid-shaped cg-G. b Schematic structure of cg-G. Three colorful points a (green), b (yellow), and c (purple) represent three different positions on the assembly. c SEM images of point a and point b in (b). The position close to the center of curvature shows obvious curvature gradient structure. d SEM image of point c and corresponding enlarged image. The structure of point c is composed of parallel graphene walls and gaps between them. e SEM images of graphene sheets in cg-G before and after evaporate-casting. f STEM images of point c in Fig. 2b after evaporate-casting. Yellow arrows represent the aligned direction of compact graphene walls. g Specific compressive strength comparison of various densified materials including normal graphene hydrogel after dehydration, graphite, kinds of metals, and cg-G after evaporate-casting (n = 3, error bar: standard deviation). Source data are provided as a source data file.