How the orientation of graphene is determined during chemical vapor deposition growth

We present a theoretical study on the determination of graphene orientation on the catalyst surface in chemical vapor deposition growth. Our study reveals that the interaction between the graphene wall and catalyst surface is weak and not sensitive to the orientation of graphene. The graphene edge-catalyst interaction is strong and sensitively depends on the graphene orientation. Therefore, the graphene edge-catalyst interaction is responsible for the orientation determination of a small graphene island in the early stage of graphene growth, and such an orientation can be inherited by the matured graphene due to the high barrier of graphene island rotation. On the basis of the mechanism of graphene orientation determination, various controversial-like experimental puzzles have been well-explained, and a potential of synthesizing large-area single-crystalline graphene on either single-crystalline or polycrystalline catalyst surfaces is revealed.