Effect of pyrolysis temperature of ionic liquid precursor on local structure and magnetic properties of nitrogen-containing graphitic carbon materials

Nitrogen-doped graphitic carbon materials were synthesized from 1-butyl-3-methylimidazolium tricyanomethanide ([BMIm][TCM]) ionic liquid at a wide range of pyrolysis temperatures and the relationship between their chemical composition, local structure, and the position of the magnetic moment was investigated. The nitrogen content of the nitrogen-doped graphitic carbon solid was maximum at a pyrolysis temperature of 250 ◦C, and the maximum nitrogen composition at carbon = 1 was 0.39. The content of N-C=N type nitrogen was the highest in the pyrolysis sample at 250 ◦C, but it decreased sharply with increasing pyrolysis temperature, and an increase the relative ratio of graphitic nitrogen and pyrrolic nitrogen was observed. At pyrolysis temperatures above 400 °C, a decrease in the nitrogen content of all bonds was observed, while an increase in magnetic moment was observed up to about 600 °C, and no correlation was found between the N content and magnetic moment.