High pressure study of nitrogen doped carbon nanotubes using Raman spectroscopy and synchrotron X-ray diffraction

• Published in: Arabian journal of chemistry 2020-01, Vol.13 (1), p.3008-3016
• Main Authors: Shi, Weiguang, Liu, Hao, Dong, Zhaohui, Mi, Zhongying, Shieh, Sean R., Sun, Xueliang, Liu, Xiaoyang
• Format: Article
• Language: English
• Subjects: High pressure behaviours; M-carbon phase; Nitrogen doped carbon nanotube; Phase transformation; Raman spectroscopy; Synchrotron radiation
• ISSN: 1878-5352; 1878-5379
• DOI: 10.1016/j.arabjc.2018.08.010

[Display omitted] In this study, nitrogen-doped carbon nanotubes (CNx-NTs) with a 8.4% nitrogen content were investigated under high pressure using Raman spectroscopy as well as X ray diffraction (XRD) with synchrotron radiation. For comparison purpose, high pressure behaviors of carbon nanotubes (CNTs) without nitrogen were studied as well. Two phase transformations were identified in CNx-NTs, which can be assigned to tube shape change from circular to ellipse-like and then to flatten shape. In strong contrast, no obvious phase transition was found in CNTs. In addition to the tube shape change, a high pressure M-carbon phase was also evidenced by XRD. Both CNTs and CNx-NTs showed axial dependent compressibility under high pressure. Furthermore, this study found the CNx-NTs acted more complexly than carbon in other forms such as single wall CNTs, multiwall CNTs, and graphite, suggesting the doping of nitrogen in addition to the wall thickness affect the properties of CNx-NTs under high pressure. Especially the doping of nitrogen could also help to extend the appearance of M-carbon phase to lower pressure range. Finally, the TEM images also show the retrieved CNx-NTs were partially amorphousized, which was believed due to the high pressure M-carbon phase formed at high pressure.