Electron Paramagnetic Resonance Investigation of Purified Catalyst-free Single-Walled Carbon Nanotubes

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• 作者：Mujtaba Zaka ; Yasuhiro Ito ; Huiliang Wang ; Wenjing Yan ; Alex Robertson ; Yimin A. Wu ; Mark H. Rümmeli ; David Staunton ; Takeshi Hashimoto ; John J. L. Morton ; Arzhang Ardavan ; G. Andrew D. Briggs ; Jamie H. Warner
• 刊名：ACS Nano
• 出版年：2010
• 出版时间：December 28, 2010
• 年：2010
• 卷：4
• 期：12
• 页码：7708-7716
• 全文大小：637K
• 年卷期：0
• ISSN：1936-086X

文摘

Electron paramagnetic resonance of single-walled carbon nanotubes (SWCNTs) has been bedevilled by the presence of paramagnetic impurities. To address this, SWCNTs produced by laser ablation with a nonmagnetic PtRhRe catalyst were purified through a multiple step centrifugation process in order to remove amorphous carbon and catalyst impurities. Centrifugation of a SWCNT solution resulted in sedimentation of carbon nanotube bundles containing clusters of catalyst particles, while isolated nanotubes with reduced catalyst particle content remained in the supernatant. Further ultracentrifugation resulted in highly purified SWCNT samples with a narrow diameter distribution and almost no detectable catalyst particles. Electron paramagnetic resonance (EPR) signals were detected only for samples which contained catalyst particles, with the ultracentrifuged SWCNTs showing no EPR signal at X-band (9.4 GHz) and fields < 0.4 T.