Mechanisms of graphene growth by chemical vapour deposition on transition metals

Graphene has become the focus of research recently due to its properties. Various methods have been proposed for the synthesis of graphene, and chemical vapour deposition (CVD) appears to be the most promising route for synthesising large-area graphene. Use of Ru, Ir, Ni, or Co lead to a segregation growth procedure, in which carbon dissolves into the bulk metals at a high temperature and segregates to form graphene after reaching the carbon saturation, and the graphene expand with carpet growth mode. For Cu catalyst, the formation of graphene can be explained by the surface growth model, in which carbon aggregates at the surface of Cu to form graphene. Graphene are formed at different mechanism on different crystalline facets for Pt, Ni and Cu. Meanwhile Ru(0 0 0 1) and Ir(1 1 1) only suitable for graphene formation for respective metals. This review discusses the fundamental mechanisms of the synthesis of graphene from various transition metals under various circumstances through a CVD process and concludes by addressing the challenges involved in large-scale graphene synthesis and the reuse of the catalysts.