Monolayer graphene growth using additional etching process in atmospheric pressure chemical vapor deposition

The synthesis of monolayer graphene is the key to graphene's practical applications. Herein we report a facile and scalable technique to grow monolayer graphene on Cu, Ni, Co, and Fe surfaces using an etching-aided chemical vapor deposition (CVD) process. The growth was performed using an additional step of hydrogen etching in atmospheric pressure CVD after stopping the carbon supply. The etching of formed multi-layer graphene for Cu substrates assists the formation of monolayer graphene. The etching of excessive dissolved carbon for Ni, Co, and Fe substrates really helps to suppress the troublesome carbon precipitation which is believed to cause the non-uniform thickness of the produced graphene. We believe this technique is not only limited to Cu, Ni, Co, and Fe surfaces but also can be extend to other metal substrates such as Pt, Au, Pd, and Ru if choosing appropriate carbon precursors. We also found out that by varying the time of hydrogen exposure both monolayer and bilayer graphene were successfully synthesized on Ni surfaces. Metal substrates with high carbon solubility in them seem to hold great advantages in the layer-controlled synthesis of graphene. Our findings open a new pathway for an efficient growth of monolayer graphene and will facilitate graphene research.