In situ observations of graphene growth and strong graphene‑nickel interactions by grazing incidence X-ray diffraction

Abstract

The growth mechanisms of graphene on polycrystalline Ni by chemical vapor deposition using polymethyl methacrylate (PMMA) as solid-state carbon sources were investigated by in-situ two-dimensional grazing incidence X-ray diffraction (GIXRD). The results show that the formation of graphene can be described by four stages: The graphitization of solid-state carbon, carbon dissolution in Ni, graphene nucleation, and isothermal growth of graphene, suggesting that the graphitization mechanism is metal-induced crystallization (MIC) mechanism. The so-called induction is mutual, that is, Ni induces the growth of graphene, and reciprocally, graphene induces the rotation and reorientation of Ni. The reorientation of Ni is the enhancement of Ni(111). The rotation and reorientation of Ni occur simultaneously with the nucleation of graphene and continue throughout the growth of graphene. The rotation of Ni ends when the graphene growth stops. Further, the forces causing the rotation and reorientation of the surface Ni lattice are analyzed. It was discovered for the first time that grain rotation was caused by directional carbon diffusion and graphene-Ni interaction. In addition, when the growth temperature is the same, the time when graphene starts to grow is mainly related to the nickel matrix but not the carbon source.