Nanomechanics of carbon honeycomb cellular structures

Recently synthesized graphitic honeycomb structures, consisting of sp2-bonded graphene nanoribbons connected by sp3-bonded “hinges” are investigated theoretically. Honeycombs of different “wall-chiralities” (armchair and zigzag) and sizes are studied. Simulation of the reconstruction of the hinges shows that zigzag honeycombs spontaneously rearrange, resulting in a new structure. Elastic mechanical simulations show that the Young's modulus of the structures is determined solely by the density of the hinges, regardless of the structural orientation or regularity. Compression tests display a distinct behavior of self-localized deformation, similar to that of macroscopic honeycombs. Interestingly, the failure strain of the honeycomb structure is affected significantly by its lattice size and geometrical regularity. Electronic band structures of different types of honeycombs are calculated, showing that the conductivity of armchair honeycombs follows the well-known “3n”-dependency, while zigzag honeycombs are always metallic.