Electronic Structure and Field‐Emission Properties of Nitrogen‐Doped Carbon Nanotubes

Abstract

Nitrogen‐doped carbon nanotubes have been synthesized by thermal decomposition of acetonitrile vapor over Ni/Co catalysts with varied ratio of metals. X‐ray photoelectron spectroscopy revealed that nitrogen atoms are embedded into tube walls in two different forms at least: (1) three‐coordinated nitrogen and (2) pyridinic‐like nitrogen. The ratio between these forms depends on the catalyst composition. Electronic structure of nitrogen‐doped carbon nanotubes was examined by means of photoemission, X‐ray photoelectron, X‐ray emission and X‐ray absorption spectroscopy. Field electron emission characteristics of samples produced were correlated with nitrogen content. The experimental data was interpreted using results of quantum‐chemical semiempirical AM1 calculations on models of nitrogen‐containing carbon tubes. Incorporation of three‐coordinated nitrogen was found from calculation of the models using the transfer matrix approximation to improve the current‐voltage characteristics of carbon nanotubes.

Keywords:

• Nitrogen‐doped carbon nanotubes
• electronic structure
• X‐ray spectroscopy
• field emission
• quantum‐chemical calculation

Acknowledgment

We are thankful to Mr. O.G. Abrosimov for the TEM images to Dr. I.P. Asanov for the XPS data. The work was financially supported by European Office of Aerospace Research and Development (grant CRDF RUP1‐1501‐NO‐04) and by the bilateral program “Russian-German Laboratory at BESSY”.