Nitrogen doping effects on the structure behavior and the field emission performance of double-walled carbon nanotubes

The nitrogen (N) doping effect and field emission properties of double-walled carbon nanotubes (DWCNTs) were investigated. Diameter transformation and defect generation in the N-doped DWCNTs mainly depend on the amount of nitrogen employed. By applying N-doping into DWCNTs (1.5 N at.%), the average diameters of the DWCNTs were increased from 1.7 to 2.4 nm, and the crystallinity (I-G/I-D) was decreased from 13.5 to 5. Field emission properties were enhanced by the N doping into DWCNTs. The turn-on field, corresponding to a current density of 0.1 mu A/cm(2), was about 0.9V/mu m for the N-doped DWCNTs (1.5 N at.%). The field enhancement factor of the N-doped DWCNTs was higher than that of the undoped DWCNTs. It was found that the field emission properties were controlled by pyridine-like N in the graphite due to N-doping. (C) 2008 Elsevier Ltd. All rights reserved.