Nitrogen controlled iron catalyst phase during carbon nanotube growth

Author(s)
Bernhard C. Bayer, Carsten Baehtz, Piran R. Kidambi, Robert S. Weatherup, Clemens Mangler, Jani Kotakoski, Caroline J. L. Goddard, Sabina Caneva, Andrea Cabrero-Vilatela, Jannik C. Meyer, Stephan Hofmann
Abstract

Close control over the active catalyst phase and hence carbon nanotube structure remains challenging in catalytic chemical vapor deposition since multiple competing active catalyst phases typically co-exist under realistic synthesis conditions. Here, using in-situ X-ray diffractometry, we show that the phase of supported iron catalyst particles can be reliably controlled via the addition of NH3 during nanotube synthesis. Unlike polydisperse catalyst phase mixtures during H-2 diluted nanotube growth, nitrogen addition controllably leads to phase-pure gamma-Fe during pre-treatment and to phase-pure Fe3C during growth. We rationalize these findings in the context of ternary Fe-C-N phase diagram calculations and, thus, highlight the use of pre-treatment- and add-gases as a key parameter towards controlled carbon nanotube growth.

Organisation(s)
Physics of Nanostructured Materials
External organisation(s)
University of Cambridge, Helmholtz-Zentrum Dresden-Rossendorf
Journal
Applied Physics Letters
Volume
105
No. of pages
5
ISSN
0003-6951
DOI
https://doi.org/10.1063/1.4897950
Publication date
10-2014
Peer reviewed
Yes
Austrian Fields of Science 2012
210006 Nanotechnology, 103008 Experimental physics, 103009 Solid state physics
Keywords
ASJC Scopus subject areas
Physics and Astronomy (miscellaneous)
Portal url
https://ucris.univie.ac.at/portal/en/publications/nitrogen-controlled-iron-catalyst-phase-during-carbon-nanotube-growth(8140e3eb-bd25-4772-9e36-8b21c33c9cb7).html