Structural and Compositional Regulation of Nitrogen-Doped Carbon Nanotubes with Nitrogen-Containing Aromatic Precursors

Nitrogen-doped carbon nanotubes (NCNTs) have been catalytically synthesized from five different nitrogen-containing aromatic precursors by injection chemical vapor deposition (CVD) in the temperature range of 550-850 degrees C. The doped nitrogen mainly exists as pyridinic or graphitic nitrogen with the total content of 2-9 at. % depending on the precursor and preparation condition. Over 60% carbon and nitrogen atoms could be converted to NCNTs products for all the precursors, indicating the high efficiency and potential for scale-up of the injection CVD method. The oxidation processes of the NCNTs products have been illustrated in detail with the in situ thermogravimetry-differential scanning calorimetry-mass spectrum coupling technique, and the results clearly indicate the successful incorporation of nitrogen into the nanotubes as supported by X-ray photoelectron spectroscopy. There is a dependent correlation between the pre-existing C-N bond in the precursor and the N incorporation in the corresponding NCNTs product. This suggests a general preparation strategy of NCNTs for scale-up and regulation of nitrogen content and status.