Reactivity of Carbon Nanofibers with Fluorine Gas
Abstract
The present study highlights the reactivity of carbon nanofibers (CNFs) with fluorine gas. Highly purified and graphitized CNFs were treated under a stream of fluorine gas for 16 h at temperatures ranging from 380 to 480 °C. Different fluorination temperature zones have been revealed by direct physicochemical analysis such as XRD, Raman spectroscopy, EPR, and solid-state NMR (^(13)C and ^(19)F). The comparison between various parameters such as covalence of C−F bond, T_1 spin−lattice nuclear relaxation time, density, and environment of the dangling bonds, among others, allows the fluorination mechanism to be determined, i.e., the formation of (C_2F)_n type graphite fluoride as the precursor of richer (CF)_n compound. This is supported by TEM characterization as the fluorination proceeds from the external parts of the carbon nanofibers and then propagates through the core without a major structural change of the fluorinated parts. A low exfoliation of the sheets is necessary for extended fluorination and conversion into (CF)_n; this occurs for fluorination temperatures higher than 472 °C, with concomitant disappearance of the graphitic structure.
Additional Information
© 2007 American Chemical Society. Received 25 July 2006. Published online 23 December 2006. Published in print 1 January 2007. The authors thank MER Corporation, Tucson, AZ, for generously providing the CNFs and Dr. William Stone from the Service de Matière Condensée et Résonance Magnétique (Université Libre de Bruxelles, Belgium) for valuable discussions concerning this work.Additional details
- Eprint ID
- 74017
- DOI
- 10.1021/cm061731m
- Resolver ID
- CaltechAUTHORS:20170203-100737590
- Created
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2017-02-03Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field