title: Upper limit of nitrogen content in carbon materials.
abstract: Nitrogen-doped carbon materials (NDCs) play an important role in various fields. A great deal of effort has been devoted to obtaining carbon materials with a high nitrogen content; however, much is still unknown about the structure of the nitrogen-doped materials and the maximum nitrogen content possible for such compounds. Here, we demonstrate an interesting relationship between the N/C molar ratio and the N content of NDCs. The upper limit for the nitrogen content of NDCs that might be achieved was estimated and found to strongly depend on the carbonization temperature (14.32 wt% at 1000 °C and 21.66 wt% at 900 °C), irrespective of the precursor or preparation conditions. Simulations suggest that, especially in the carbon architectures obtained at high temperatures, nitrogen atoms are always located on separate hexagon moieties in a graphitic configuration, thereby yielding a critical N/C molar ratio very close to the value estimated from the experimental results.
authors.affiliation: Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan) http://mwatalab.xsrv.jp/
authors.forename: Shiguo
authors.initials: S
authors.lastname: Zhang
authors.forename: Seiji
authors.initials: S
authors.lastname: Tsuzuki
authors.forename: Kazuhide
authors.initials: K
authors.lastname: Ueno
authors.forename: Kaoru
authors.initials: K
authors.lastname: Dokko
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Watanabe
keywords: carbon; carbon nitride; materials science; nitrogen