▎ 摘　　要

To understand the nucleation of carbon atoms to form graphene on transition metal substrates during chemical vapor deposition (CVD) synthesis, carbon clusters supported on Ni(111) surfaces, namely C(N)@Ni(111) (where N 12. A ground state structural transition from a one-dimensional C chain to a two-dimensional sp(2) network (or graphene island) occurs at N = 12. It is surprising that incorporating one to three 5-membered-rings (5MRs) or pentagons into a graphene island is required to achieve the energetically most stable structure. This deep insight into the supported C cluster formation is crucial for understanding the growth mechanism of graphene on a transition metal surfaces in CVD experiments and the experimental design of CVD graphene growth.