Structure and stability of graphene edges in O2 and H2 environments from ab initio thermodynamics

Abstract

Edges play a determining role in the electronic and transport properties of graphene, how-ever, their actual morphology and configuration remain unknown. Using ab initio thermo-dynamics, we have systematically studied the stability and structure of armchair andzigzag edges of graphene in pure O2and combined O2and H2environments. In total, 81different nanostructures were investigated, however, only a few of them domain the phasediagram. Our calculations show that zigzag edges are less stable than armchair edges.Nonetheless, the former exhibit a much richer diversity in terms of structures. The oxy-gen-terminated edges occupy the largest regions in the phase stability diagram in compar-ison with hydrogen-oxygen-terminated edges, which correspond to carboxyl and alcoholfunctional groups