Structural control and structural analyses of defects in carbon materials

Controlling the types of defects in carbon materials is essential for improving the properties for various applications. However, controlling defect structures in carbon materials is challenging in the absence of catalysts. We have recently synthesized carbon materials with an exceptionally high percentage of pyridinic nitrogen at 973 K (92%), pyrrolic nitrogen at 873 K (94%), tertiary nitrogen at 973 K (92–98%), pentagons-heptagons at 873–973 K (90%), pentagons at 773 K (96% retained from the precursor), edges with one sp2C–H on one benzene ring (SOLO) at 823 K (100%), and zigzag/armchair edges at 775 K (100% retained from the precursor) without using catalysts by the simple heat treatment of the precursors in ampoules. Since catalysts are unnecessary and mass synthesis is possible, these carbon materials are expected to be useful for various applications. To precisely analyze the structures of the carbon materials in a short time, we used a combination of X-ray photoelectron, infrared, Raman, and nuclear magnetic resonance spectroscopy with density functional theory calculations of these spectra, combustion elemental analysis, and molecular dynamics simulations with a reactive force field. These results resolved the reasons for the previously reported ambiguous assignments of the spectral analyses of carbon materials with complicated structures.