Journal of Materials Science ( IF 3.5 ) Pub Date : 2021-07-12 , DOI: 10.1007/s10853-021-06283-5 Tomofumi Kato 1 , Yasuhiro Yamada 1 , Hayato Sato 1 , Satoshi Sato 1 , Yasushi Nishikawa 2 , Toshiya Otomo 3
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X-ray photoelectron spectroscopy (XPS) is among the most powerful techniques to analyse structures of nitrogen-doped carbon materials. However, reported assignments of (1) graphitic nitrogen (N)/substitutional N, quaternary N (Q–N), or tertiary amine (T–N) and (2) pyrrolic N/secondary amine or T–N are questionable. Most reports assign peaks at ca. 401 eV as Q–N or graphitic N, whereas raw materials in most of those works contain neither counter anion nor halogen. Besides, the peak at ca. 400 eV has been assigned as pyrrolic N, but the presence of N–H is generally not confirmed. In this work, it was clarified that one of the reasons for the prevailing ambiguous assignments is the presence of N in heptagonal and pentagonal rings. The peaks at 400.1–401.2 eV were determined to be T–N, but not Q–N by analyzing graphitized polyimide (with the oxygen content of 0.01 at% or lower and the hydrogen content of 0 at%) using Raman spectroscopy, XPS, X-ray diffraction, total neutron scattering, elemental analysis, and molecular dynamics simulation. Besides, it was revealed that the peak at 400.1 eV originated from T–N on 5-membered rings or 7- and 5-membered rings, but not pyrrolic N because graphite including no hydrogen was used for analysis.
Graphical abstract
中文翻译：
碳材料的N1s X射线光电子能谱中石墨和吡咯氮峰的起源：季氮，叔胺，还是仲胺？
X 射线光电子能谱 (XPS) 是分析掺氮碳材料结构的最强大技术之一。然而，(1) 石墨氮 (N)/取代 N、季 N (Q–N) 或叔胺 (T–N) 和 (2) 吡咯 N/仲胺或 T–N 的报告分配是有问题的。大多数报告将峰值指定为大约。401 eV 作为 Q-N 或石墨 N，而大多数这些作品中的原材料既不含抗衡阴离子也不含卤素。此外，在大约峰值。400 eV 已被指定为吡咯 N，但 N-H 的存在通常未被证实。在这项工作中，澄清了普遍存在的模糊分配的原因之一是 N 在七边形和五边形环中的存在。400.1-401.2 eV 的峰被确定为 T-N，通过使用拉曼光谱、XPS、X 射线衍射、总中子散射、元素分析和分子动力学分析石墨化聚酰亚胺（氧含量为 0.01 at% 或更低，氢含量为 0 at%），而不是 Q-N模拟。此外，还发现 400.1 eV 处的峰源自 5 元环或 7 和 5 元环上的 T-N，而不是吡咯 N，因为用于分析的石墨不含氢。
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