Upper Limit of Nitrogen Content in Carbon Materials

• Published in: Angewandte Chemie International Edition 2015-01, Vol.54 (4), p.1302-1306
• Main Authors: Zhang, Shiguo, Tsuzuki, Seiji, Ueno, Kazuhide, Dokko, Kaoru, Watanabe, Masayoshi
• Format: Article
• Language: English
• Subjects: Carbon; carbon nitride; Carbonization; Doping; Hexagons; materials science; nitrogen; Nitrogen atoms; Precursors; Simulation
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201410234

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. Doping control: The relationship between the nitrogen/carbon molar ratio and nitrogen content in nitrogen‐doped carbon materials (NDCs) has been found to depend only on the carbonization temperature, being irrespective of the precursor, carbon type, and preparation conditions. The upper limit for the nitrogen content was explained by an energetically favorable graphitic N‐doping configuration.