▎ 摘　　要

We present a simple and convenient route to freestanding graphene nanosheets and large-area/patterned graphene nanofilms by thermal annealing of an indium (In) and graphite mixture. In particles mixed with graphite powder catalytically oxidize the graphite powder and produce carbon oxide gases. The carbon oxide gases are then catalytically graphitized to form graphene nanostructures on In. The morphologies of the graphene nanostructures can be controlled by the In geometry: vertically-standing graphene nanosheets are synthesized using In particles and a graphene nanofilm is grown on a thin In layer. In is then completely removed, and thus high-purity graphene is finally produced. The graphene nanosheets exhibited excellent field-emission performance due to high-density edges. In addition, the graphene nanofilms show electrical conductivities comparable to or better than that of reduced graphene oxide. Furthermore, a large-area or a patterned graphene nanofilm is synthesized using a uniform or a pre-patterned In layer, respectively.