Fig. 4.

DFT simulation of graphene grain boundary energetics with methane partial pressure. a, b represent two random mis-orientations GB1 and GB2, respectively. For both, the grain edge passivated with hydrogen, blue atoms, and defect structure on boundary formation are shown. c The free energy change, ΔG, for these two configurations as per equation (3) vs methane partial pressure. A crossover in the plot suggests that depending on the methane partial pressure the reaction can proceed in the forward or backward direction. Increase in pressure favors boundary formation and vice-versa as observed experimentally. The pressure at which it happens depends on the boundary misorientation