Influence of different buffer gases on synthesis of few-layered graphene by arc discharge method

Few-layered graphene sheets were synthesized by direct current arc discharge using different buffer gases. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and four-probe method. Moreover, the hydrophobility and the field emission properties of the sprayed-coating graphene films prepared by a direct solution process were studied. As a result, the generation of graphene sheets shows strong dependence on the composition of buffer gases and containing H2 buffer gases are necessary to prepare few-layered graphene sheets. The graphene sheets produced in H2–He buffer gases have better crystallinity and higher specific surface area compared with those produced in others containing H2 buffer gases. The as-obtained graphene sheets are mainly no more than 5 layers and their lateral dimensions are about 40–200 nm. The graphene sheets show excellent thermal stability and there is only less than 3 wt.% weight loss up to 800 °C in N2 atmosphere. The graphene sheets can be easily dispersed into ethanol and the as-obtained suspension can be stable for more than two months. The sprayed graphene films show good hydrophobility and a typical cold cathode field emission behavior.