NANO LETTERS
Comments on “NanoTeflons: Structure and EELS Characterization of Fluorinated Carbon Nanotubes and Nanofibers”
2004 Vol. 4, No. 5 999
Vinay Gupta Department of Physics, Ilmenau Technical UniVersity, Ilmenau 98684, Germany Received January 19, 2004; Revised Manuscript Received February 3, 2004
The above article1 reports, high-resolution electron energy loss spectroscopy (HREELS) studies with other characterizations on fluorinated carbon nanotubes and nanofibers of various diameters. It was concluded that these fluorinated compounds contained both ionic and covalent bonding, so could they be termed teflons since teflons have essentially covalent C-F bonding. In the abstract, it is stated that “EELS calculations using density functional theory confirmed the existence of covalent and ionic F bonded to the carbon within the tubes at ∼685 and 690 eV, respectively”, which is fundamentally wrong because covalent F-C bonding should be at 690 eV, whereas ionic bonding should be at 685 eV. Moreover, the computed values given in Figure 4, show ionic bonding at ∼681.5 eV (shown in red) and covalent bonding at ∼685 eV (shown in blue). These values are impractical and contradictory to the above statement of the authors. Further in the abstract, it is stated that “These values are in good agreement with those obtained experimentally”, which
10.1021/nl049885t CCC: $27.50 Published on Web 04/09/2004
© 2004 American Chemical Society
is also not possible since the calculated values of binding energies are themselves impractical. On page 493 (paragraph 3, line 7) it is stated that “The ELNES for the fluorine edge usually consists of a main peak centered at ∼688.5 eV and a shoulder located at ∼683.2 eV (Figure 2b). These energies can be attributed to the presence of ionic and covalently bonded F to the graphene sheet”. On page 493 (paragraph 5, line 5) it is stated that “The main peak centered at ∼688.5 eV should arise from the covalently bonded fluorine”. In the abstract, the binding energy for same covalently bonded fluorine was given as 685 eV. All these values contradict each other. References (1) Hayashi, T.; Terrones, M.; Scheu, C.; Kim, Y. A.; Ruhle, M.; Nakajima, T.; Endo, M. Nano Lett. 2002, 5, 491.
NL049885T
