▎ 摘　　要

Graphene emitters with high enhancement factor and ultra low emission field were exfoliated from carbon fibers in carbon cloth. This method made the graphene sheets to stay on the carbon fiber and were used, in situ, as emitters. Due to their high multistage enhancement factor and intrinsic good contact, electron emission from these graphene sheets required ultra low emission field. The threshold-field corresponding to emission current density of 1 mA/cm(2) was about 0.7V/mu m. This high enhancement factor was attributed to the effects of the high aspect ratio of graphene sheets and the geometry of carbon cloth. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4758291]