ABSTRACT
Graphene is a monolayer of sp2-bonded carbon atoms that are packed in a honeycomb crystal lattice, that is, single layer of graphite (Figure 20.1).1,2 ¡is 2D allotrope of carbon is mechanically very strong, showing a breaking strength that is 200 times greater than steel, a measured spring constant on the order of 1-5 N/m, and a Young’s modulus of 0.5 TPa (cf. graphite ∼0.01 TPa) from atomic force microscope experiments.3
