Selective doping of pyridinic nitrogen in carbon materials has attracted attention due to its significant properties for various applications such as catalysts and electrodes. However, selective doping of pyridinic nitrogen together with controlling skeletal structure is challenging in the absence of catalysts. In this work, four precursors including four fused aromatic rings and pyridinic nitrogen were simply carbonized in the absence of catalysts in order to attain mass synthesis at low cost and a high percentage of pyridinic nitrogen in carbon materials with controlled edges. Among four precursors, dibenzo[f,h] quinoline (DQ) showed an extremely high percentage of pyridinic nitrogen (96 and 86%) after heat treatment at 923 and 973 K, respectively. Experimental spectroscopic analyses combined with calculated spectroscopic analyses using density functional theory calculations unveiled that the C-H next to the pyridinic nitrogen in DQ generated gulf edge structures with controlled pyridinic nitrogen after carbonization. By comparing the reactivities among the four precursors, three main factors required for maintaining the pyridinic nitrogen in carbon materials with controlled edges, such as (1) high thermal stability of the pyridinic nitrogen, (2) the presence of one pyridinic nitrogen in one ring, and (3) the formation of gulf edges including pyridinic nitrogen to protect the pyridinic nitrogen by the C-H groups on the gulf edges, were revealed.

Synthesis of carbon materials with extremely high pyridinic-nitrogen content and controlled edges from aromatic compounds with highly symmetric skeletons
    Abstract
        Graphical abstract
    1 Introduction
    2 Methods
        2.1 Experimental
        2.2 Calculations
            2.2.1 Molecular dynamics simulation with a reactive force field
            2.2.2 DFT calculations
    3 Results and discussion
        3.1 Combustion elemental analyses
        3.2 XPS analyses
        3.3 IR analyses
            3.3.1 DQ
            3.3.2 DQX
            3.3.3 QQ
            3.3.4 DP
        3.4 Raman analyses
        3.5 13C NMR analyses
        3.6 DFT calculations
            3.6.1 Calculations of formation energy
                3.6.1.1 Dehydrogenation (Scission of C–H bonding) 
                3.6.1.2 Hydrogenation (formation of N–H bonding) 
                3.6.1.3 Formation of C–N bonding 
            3.6.2 Orbital energies and Mulliken charge
            3.6.3 Clar’s rule and bond length
        3.7 Screening precursors by ReaxFF
        3.8 Probable reaction route
        3.9 Factors that govern the percentage of pyridinic N
    4 Conclusion
    Anchor 31
    Acknowledgements 
    References

• Taisei Taguchi(Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1‑33 Yayoi, Inage, Chiba 263‑8522, Japan)
• Syun Gohda(Nippon Shokubai Co., Ltd., 5‑8 Nishiotabi, Suita, Osaka 564‑0034, Japan)
• Kazuma Gotoh(Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology (JAIST), 1‑1 Asahidai, Nomi, Ishikawa 923‑1292, Japan)
• Satoshi Sato(Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1‑33 Yayoi, Inage, Chiba 263‑8522, Japan)
• Yasuhiro Yamada(Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1‑33 Yayoi, Inage, Chiba 263‑8522, Japan)