Carbon nanotube separation by electronic type using a single surfactant-based density-induced separation method

Hyerim Choi, Won Jung Yoon, Heather Yang, Woo Jae Kim

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We demonstrate a simple and efficient method for separating metallic from semiconducting singlewalled carbon nanotubes (SWNTs) using density-gradient ultracentrifugation. Density differences between metallic and semiconducting SWNTs, which enable SWNT separation by electronic type, are created using a single surfactant, i.e., sodium dodecyl sulfate (SDS), rather than a complex mixtures of surfactant, as is used in current separation schemes. SDS strongly adsorbs onto the surface of metallic SWNTs over semiconducting SWNTs by the mirror-charge phenomenon. Therefore, metallic SWNT-SDS assemblies have relatively smaller buoyant densities than semiconducting SWNT-SDS assemblies; thus, the metallic assemblies are easily collected at the most buoyant top fractions, whereas the semiconducting assemblies are collected at the bottom fractions. We also demonstrate that this protocol is valid regardless of the SWNT production method; that is, SWNTs grown by high-pressure carbon monoxide conversion (HiPco) and the arc discharge method. Optical absorption shows that the heavy bottom fractions consist of highly pure semiconducting nanotubes, whereas the buoyant top fractions consist of highly pure metallic nanotubes. In addition, films made of the separated metallic SWNTs exhibit lower sheet resistances than unsorted SWNTs by 53% for arc discharged and 64% for HiPco SWNTs, as expected.

Original languageEnglish
Pages (from-to)9165-9168
Number of pages4
JournalJournal of Nanoscience and Nanotechnology
Issue number12
StatePublished - 1 Dec 2014

Bibliographical note

Publisher Copyright:
Copyright © 2014 American Scientific Publishers All rights reserved.


  • Density-gradient ultracentrifugation (DGU)
  • Metallic SWNTs
  • SDS
  • Semiconducting SWNTs
  • Single surfactant
  • SWNT separation


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