First-principles investigations on the adsorption and diffusion of carbon atoms on the surface and in the subsurface of Co (111) related to the growth of graphene

Abstract

The adsorption and diffusion of carbon atoms on the surface of a catalyst are key steps in the chemical vapor deposition of carbon nanomaterials. Using first-principles density functional theory, the adsorption and diffusion of carbon atoms on the surface and in the subsurface of Co (111) have been systematically investigated to identify the catalyzed growth of graphene on Co (111). In view of the maximization of the adsorption energy, the hexagonal close-packed site and the octahedral site are the most stable sites for carbon atoms on the surface and in the subsurface of Co (111), respectively. Furthermore, to reveal the rate-determining step of the growth of graphene, the energy barriers for the diffusion of carbon atoms on the surface of Co (111) and from the subsurface to the surface have been obtained. The Co (111) surface has the highest mobility for carbon atoms due to the lower diffusion energy barrier, and the vertical diffusion of carbon atoms from the subsurface to the surface is relatively difficult due to the higher diffusion energy barrier. The results may be related to the growth of graphene on Co (111) and we come to the conclusion that the direct surface growth should be the predominant way for the synthesis of graphene on Co (111).