| Carbon nanotube (CNT) is one dimensional carbon material with tubular structure, which has excellent electrical, thermal and mechanical properties, large aspect ratio and low work function, being regarded as one of ideal field emission materials. In this paper, we study the field emission property of CNTs from three aspects, including field emission properties of CNT, especially single walled carbon nanotubes (SWCNTs) on indium tin oxide glass (ITO glass), field emission performance with different substrate, field emission properties of CNTs composed with graphene and other sp2 carbon nanomaterials.The first chapter is introduction about CNT. Information about CNTs, including structure, property, preparation, application and characterization method, is introduced. Field emission theory and latest study developments of CNT field emission are also mentioned.The second chapter is the study on field emission properties of CNT on ITO glass, especially the preparation of SWGNT and their field emission. Chemical vapor deposition was used to prepare SWCNT with different hydrogen (H2) flow, catalyst and volume of ethanol, and their field emission was studied. SWCNT was also prepared by arc discharge, and field emission property was compared with purchased MWCNT using screen printing.The third chapter is about the study of field emission performance on different substrate. Four kinds of CNTs with different diameter and length were used on NF substrate, and the result shows CNT with small diameter and short length has best field emission property. In the experiment, ITO glass, nickel foil (Ni) and nickel foam (NF) substrates were used, and CNT on NF has the best field emission performance with low turn-on electric field and very high field enhancement factor. The enhancement field emission property of CNT/NF is attributed to the special structure of NF, which has better electrical conduction and heat dissipation than flat substrate, and NF composite a multistage structure with CNT, largely enhanced field enhancement factor.The fourth chapter is field emission properties of CNTs composed with graphene and other sp2 carbon nanomaterials. CNT/graphene hybrid and CNT/graphene mixture were prepared by two methode, and their field emission properties were studied. CNT/graphene hybrid prepared by water-process has better field emission for the well-orgnized conductive network. The mass ratio of CNT and graphene was also studied, emphasizing the importance of both CNTs and graphene in the cathode. A model was built to analysis the reason of graphene improving CNT field emission. Graphite and reduced graphite oxide (r-graO) composite with CNT also enhanced field emission property.The fifth chapter is summary and outlook of the study in this paper. |
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