Is complete reconstruction of zigzag graphene edge possible? Kinetics of formation and annihilation of residual topological defects

Ab initio calculations are performed to investigate the reconstruction of zigzag graphene edges beyond the initial nucleation of a 57 pair and growth of reconstructed edge domains composed of 57 pairs. We calculate the energetic profiles for the final steps of domain coalescence, which result in the formation of residual topological defects serving as domain boundaries. The energy barriers for these steps range from 0.8 to 1.6 eV, indicating that they do not limit the rate of the overall reconstruction process. 7557 defect with neighboring pentagons is found to be energetically unfavourable and prone to the inclusion of a hexagon pair between the pentagons. Possible atomistic pathways for diffusion of the residual defects are proposed and analyzed, with calculated barriers ranging from 1.3 to 2.2 eV. The most mobile defect is identified as a hexagon separating two domains with the same 57 pair orientation (57657). Among defects separating domains with different orientations, those with proximal pentagons (7557 and 75657) exhibit significantly higher mobility than those with adjacent heptagons (5775 and 57675). Furthermore, defects containing a hexagon between domains (57675 and 75657) are found to be less mobile than their counterparts (5775 and 7557). Based on these results and kinetic modeling, we predict the temperature-dependent lifetimes of residual defects prior to their annihilation. Our results demonstrate that complete reconstruction of the zigzag edge is feasible at temperatures above 600 K. Analytical estimates are derived to explain the time and length scales governing the entire reconstruction process. • Defect-free zigzag edge reconstruction is feasible at temperatures above 600 K. • For edges under 200 nm, complete reconstruction can occur at 400 K. • The 7557 defect is metastable, prone to inclusion of a hexagon pair (756657). • The 57657 defect is the most mobile with a diffusion barrier of 1.3 eV. • Proximal pentagons (7557, 75657) migrate faster than adjacent heptagons (5775, 57675).