Graphene/ZnO nanocomposite with seamless interface renders photoluminescence quenching and photocatalytic activity enhancement

The interface of graphene (G) and oxide can significantly influence the properties and/or applications of the binary system. However, it is usually beyond controllability during the conventional physical intermixing and/or solvothermal preparations. In this article, by directly growing nanocrystalline graphene films on the ZnO nanocrystals through a medium-temperature chemical vapor deposition method utilizing C2H2 as the carbon source, we successfully achieved a G/ZnO binary structure with a uniform and contamination-free G/oxide interface. The fabricated G/ZnO powders not only demonstrated a clear charge transfer between graphene and ZnO that leads to photoluminescence quenching, but also manifested an enhanced activity in the photocatalytic degradation of methylene blue when the graphene thickness is optimized. This work has demonstrated the essential significance of the interface control for the functionality of the graphene/semiconductor binary systems.