  Monolayer lateral heterostructure of graphene and hexagonal boron nitride
(h-BNC) has attracted a growing attention mainly due to its tunable band-gap
character and unique physical properties at interface. Hereby, we reported the
first-time synthesis of a nearly freestanding h-BNC hybrid on a weakly coupled
substrate of Ir (111), where graphene and h-BN possessing different surface
heights and corrugations formed a perfect monolayer hybrid. With the aid of
scanning tunneling microscopy/spectroscopy (STM/STS), we demonstrated that h-BN
can patch alongside the boundary of pre-deposited graphene domains and vice
versa to form a seamless monolayer hybrid, with the realization of predominant
zigzag type chiral boundaries at the interface. Density-functional theory
calculations and STM/STS measurements aided us to reveal that this interface
between graphene and h-BN were atomically sharp in aspects of the chemical
bonding as well as the local electronic property from both theoretical and
experimental points of view.
