Temperature Programmed Desorption for Nitrogen Species in Carbon Structure : Investigation of the Decomposition Process of the Nitrogen Species

Herein, the decomposition temperatures and gases of nitrogen species formed in carbon materials were investigated via high-temperature temperature-programmed desorption (TPD) analysis of nitrogen-doped carbon with a shell-like structure of several layers of graphene as a model material, and the decomposition behavior of nitrogen species was elucidated. The decomposition temperatures and decomposition gas of six nitrogen species (N1–N6), distinguished using X-ray photoelectron spectroscopy, were determined. The N1 and N2 (pyridinic Ns) species desorbed HCN by their decomposition, whose temperatures were estimated to be 960–1120 °C. The N3 (pyrrolic N) species exhibited the lowest thermal stability among the nitrogen species and desorbed HCN via decomposition at 850–990 °C. The N4–N6 (quaternary N) species decomposed as N 2 , and the N 2 desorption reaction was predicted to proceed at the edge sites based on the density functional theory calculations. The kinetic analysis of the TPD spectra indicates that the reaction rate of N 2 desorption was determined by both the amount of quaternary N and the number of edge sites