▎ 摘　　要

Graphene can be synthesized via metal catalysis using solid carbon source. In this paper, graphene was fabricated using amorphous carbon. We further elucidated the process of carbon diffusion and graphene formation at low temperatures using a comprehensive experimental and theoretical strategy. The diffusion barrier of carbon in nickel crystal is different from that of carbon along nickel grain boundaries, resulting in that the layer of graphene is uncontrollable. Based on our findings, we identified the causes of graphene heterogeneity and the process of carbon diffusion. (C) 2020 Elsevier B.V. All rights reserved.