Fig. 2.

Nanomechanical characterization for pristine and porous GO single layers. a Representative force-deflection curves obtained by membrane-deflection experiments using a diamond AFM probe, suggesting etched sheets become softer and weaker as etching time increases. The 5-h-etched GO sheets are too weak to be measured. Representative AFM images of 3-h-etched GO prior to deflection experiments show visible pores in b, and complete rupture of the membrane after the test in c