▎ 摘　　要

Controlled growth of circular single-crystalline graphene domains has been achieved by atmospheric pressure chemical vapor deposition (APCVD) using solid copper as substrate, thereby demonstrating that the shape of the graphene grains can potentially be precisely tuned by optimizing growth parameters. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show that the round domains have smooth, clean edges that permit seamless merging of adjacent graphene. Transmission electron microscopy (TEM) and Raman spectra together indicate that the graphene film is mostly monolayer, and electron diffraction reveals that these domains are single crystals. The growth and merging of these circular graphene domains to yield single-crystal graphene films enable us to elucidate the nucleation and growth mechanism of graphene on solid copper foil substrates.