Fig. 1. Adhesive forces of different areas under different environments.

Fig. 2. The characterization of folded graphene: (a) Optical microscope image; (b) morphology image; (c) height image at red line; (d) roughness of each area.

Fig. 3. The adhesive and tribological properties of folded graphene: (a) Adhesive forces before and after rubbing of each area; (b) friction force versus load curve of each area.

Fig. 4. The influence of tip measurement history on adhesion: (a) Change in adhesion of each region; (b) SEM image of silica ball tip; (c) change in adhesion of silica ball tip before rubbing; (d) adhesion before and after silica ball tip rubbing.

Fig. 5. Production and tribological properties of freshly folded graphene: Morphology image, full view of friction, height and friction signal images at red line before folding (a)−(c) and after folding (d)−(f).