The growth modes of graphene in the initial stage of a chemical vapor-deposition process

Using first-principles techniques, the growth modes of carbon clusters including chain and island structures on the Ni (111) surface are investigated, which is crucial to understand the graphene growth in the initial stage. One of the interesting findings is that both the chains and islands of carbon have higher mobility than the single carbon atom on the Ni substrate. More importantly, it is found that there exists two different growth modes, i.e., the bonding of the carbon cluster with a carbon atom, and the bonding between two clusters. The former corresponds to the preferred growth mode of a one-dimensional carbon chain; and the latter tends to happen between two-dimensional carbon island clusters. In addition, we discussed the relationship between the strong migration ability of grapheme islands and the defect formation according to our simulation results. At last, based on the calculated Bronsted-Evans-Polanyi relation, the catalytic properties of Ni substrate for graphene growth can be well described quantitatively.