Self-Assembly Graphene Arrays on a Liquid Cu-Ag Alloy

The alloy catalysts have been introduced in synthesizing highly oriented and monolayer graphene because of the combination of excellent features of different metals. However, precise manipulation of nucleation and growth stages on the alloy surface has not been realized and thus fabrication of large-sized 2D crystal arrays has met with limited success. Under this circumstance, quest for novelty alloy catalysts has been attracting intensive efforts. Herein, with the introduction of a liquid Cu-Ag alloy, precise engineering of nucleation and growth of graphene has been achieved. Moreover, by properly modulating the composition of the Cu-Ag alloy, the shape evolution of graphene single crystals is also detected and thus results in controllable formation of round-shaped graphene arrays. We further explain the growth mechanism of graphene on the liquid Cu-Ag catalysts by binding energy between graphene and metal surfaces. It is believed that the high-quality graphene array growth on a liquid alloy may turn on new territory for controlling surface engineering of the catalyst and paving the way toward industrial production and commercial applications.