Disentangling Vacancy Oxidation on Metallicity-Sorted Carbon Nanotubes

Autor(en)

Duncan J. Mowbray, 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

Abstrakt

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.

Organisation(en)

Elektronische Materialeigenschaften

Externe Organisation(en)

University of the Basque Country, Elettra Sincrotrone Trieste, Tokyo Metropolitan University, Yachay Tech University, Max-Planck-Institut für Struktur und Dynamik der Materie, Universität Hamburg

Journal

The Journal of Physical Chemistry Part C (Nanomaterials and Interfaces)

Band

120

Seiten

18316-18322

Anzahl der Seiten

7

ISSN

1932-7447

DOI

https://doi.org/10.1021/acs.jpcc.6b06163

Publikationsdatum

08-2016

Peer-reviewed

Ja

ÖFOS 2012

103018 Materialphysik

Schlagwörter

ASJC Scopus Sachgebiete

Electronic, Optical and Magnetic Materials, Allgemeine Energie, Surfaces, Coatings and Films, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/77be3d5c-41f4-4dc6-9408-013ede2067d0