▎ 摘　　要

Large-scale, substrate-free graphene, with few-layered sheets, is synthesized by the CVD of methane over cobalt supported on magnesium oxides at 1000 degrees C in a gas flow of argon. Typically, 50 mg of the few-layered graphene materials over 500 mg of the Co/MgO catalysts are synthesized under our experimental conditions. Randomly aggregated, thin, crumpled graphene sheets stacked closely together are produced. Both carbon (94.6 at.-%) and oxygen (5.4 at.-%) are present in the graphene sheets. The oxygen may originate from air adsorbed on the graphene sheets. Our results indicate the presence of localized sp(3) defects within the sp(2) carbon network and small sp(2) domains in the few-layered graphene particles.