Influence of interface interaction on the moiré superstructures of graphene on transition-metal substrates

The formation of moiré superstructures between graphene and its underlying substrate has attracted significant attention because it significantly influences the morphology and properties of graphene. Through the density functional theory (DFT) calculations conducted on graphene/Re(0001) and graphene/Ir(111) moiré superstructures, we found that in contrast to the strain-driven moiré superstructure of graphene on weak van der Waals interacting Ir(111) substrate, the interfacial interaction dominates in the moiré superstructure of graphene on the covalently interacting Re(0001) substrate. A large strain is exerted on graphene to facilitate the interfacial interaction between graphene and Re(0001) substrate, which markedly reduces the interfacial interaction energy and stabilizes the graphene/Re(0001) moiré superstructure. The strong covalent interaction between graphene and Re(0001) substrate is closely related to the hybridization between C 2pz orbital and Re 5dz2 orbital, which is absent in the weak van der Waals interacting graphene/Ir(111) moiré superstructure.