Disentangling Vacancy Oxidation on Metallicity-Sorted Carbon Nanotubes

Duncan J. Mowbray (Korresp. Autor*in), Alejandro Perez Paz, Rosa Georgina Ruiz Soria, Markus Sauer, Paolo Lacovig, Matteo Dalmiglio, Silvano Lizzit, Kazuhiro Yanagi, Andrea Goldoni, Thomas Pichler, Paola Ayala, Angel Rubio

Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

Abstract

Pristine single-walled carbon nanotubes (SWCNTs) are rather inert to O 2 and N 2, which for low doses chemisorb only on defect sites or vacancies of the SWCNTs at the ppm level. However, very low doping has a major effect on the electronic properties and conductivity of the SWCNTs. Already at low O 2 doses (80 L), the X-ray photoelectron spectroscopy (XPS) O 1s signal becomes saturated, indicating nearly all of the SWCNT's vacancies have been oxidized. As a result, probing vacancy oxidation on SWCNTs via XPS yields spectra with rather low signal-to-noise ratios, even for metallicity-sorted SWCNTs. We show that, even under these conditions, the first-principles density functional theory calculated Kohn-Sham O 1s binding energies may be used to assign the XPS O 1s spectra for oxidized vacancies on SWCNTs into its individual components. This allows one to determine the specific functional groups or bonding environments measured. We find the XPS O 1s signal is mostly due to three O-containing functional groups on SWCNT vacancies: epoxy (C 2>O), carbonyl (C 2>C=O), and ketene (C=C=O), as ordered by abundance. Upon oxidation of nearly all of the SWCNT's vacancies, the central peak's intensity for the metallic SWCNT sample is 60% greater than that for the semiconducting SWCNT sample. This suggests a greater abundance of O-containing defect structures on the metallic SWCNT sample. For both metallic and semiconducting SWCNTs, we find O 2 does not contribute to the measured XPS O 1s spectra.

OriginalspracheEnglisch
Seiten (von - bis)18316-18322
Seitenumfang7
FachzeitschriftThe Journal of Physical Chemistry Part C (Nanomaterials and Interfaces)
Jahrgang120
Ausgabenummer32
DOIs
PublikationsstatusVeröffentlicht - 18 Aug. 2016

ÖFOS 2012

  • 103018 Materialphysik

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