Graphene is a single layer of graphite.A few-layer-graphene has been shown to be highly crystalline and semimetallic in its electronic properties.The atomically flat has been found to be ambipolar with a tiny,overlap betwwen valence and conduction bands.When a two-dimensional graphene sheet is reduced to a one-dimensional graphene sheet is reduced to a one-dimensional graphene baboribbon(GNR),As graphene width decreases both quantum confinement and edge effects become pronounced.In contrast to earlierstudies,which indicated that the electronic properties of GNRs were energy gaps in all GNRs.The calculations wre carried out with 12-14fused aromatic ring system and the widths of the GNRs were ~3nm.

   The very high mobility,gate voltage-controlled electron or hole carriers,and tuneable bandgap suggest that GNPs may be ideal for nanoscale electron-ics and have tiggered immense interest in the large-scale synthesis of GNRs.GNRs with energy gaps are beneficial for nanodevices compared with SWNTs where one-third of the nanotubes are expected to be metallic,this intrinsic semiconducative nature of GNRs may significantly simplify the favbrication of high performance fast semiconductor nanodevices.GNR synthesis on a relatively large scale has been realized recently,using a procedure similar to the purification and separation of SWNTs.The process starts by exfoliating expandable graphite made by intercalating ~350um scale graphite flakes with sulfuric acid and nitride acid at 1000℃ in forming gas for 1min,sonicating the resulting exfloliated material in a 1,2-dichloroethane solution of polyto disperse the GNRs,and centrifuging the suspension and few-layer graphene ribbons and sheets.

    The transpots measurement indicated that all sub-10nm GNRs were semiconductors,Very recently,two articles reported longgitudinal unzipping of CNTs,producing narrow and uniform GNRs.The first one suspended MWNTs in concentrated silfric acid by classic potassium permanganate oxidation that attacked C=C double bonds to afford GNRs.A chemical reduction step is required to restore electrial conductivity.The second one also started with MWNTs,but spread over Si wafer and coated with poly.The MWNT-embedded PMMA was peeled off and exposed to Ar plasma that etched away part of the MWNTs layer.GNRs with sub-10nm width have been prepared and suggest that large-scale well-aligned semiconductor nanodevices for practical applications may be possible.