A structural stability diagram of multiple vacancies and defect self-healing in graphene

Various types of multiple vacancies (MVs) in graphene nanoribbons (GNRs) and graphene are explored by quantum calculations. It is surprising that their relative stabilities highly depend on the width of the GNRs and thus is significantly different from those in graphene. A diagram of various MVs in GNRs is drawn and it is predicated that the hole in both GNRs and graphene can be annihilated. A new type of the MVs, which contains pentagon pairs and octagons (5/5 vertical bar 8), shows exceptional stability in GNRs. This study reveals the uniqueness of GNRs and a mechanism of defect self-healing in GNRs and graphene.