Fluorinated carbon nanotubes

T. Nakajima, S. Kasamatsu, Y. Matsuo, Synthesis and characterization of fluorinated carbon nanotubes, European Journal of Solid State Inorganic Chemestry, vol. 33, pp. 831-840,1996. 

A carbon-deposited film was prepared from the alumina film with 30-nm channels by the CVD technique using propylene. Fluorination was carried out by direct reaction of the film with dry fluorine gas (purity 99.7%). The film was placed in a nickel reactor and was allowed to react with 0.1 MPa of fluorine gas for 5 days at a predetennined temperature in the range of 50 to 200°C. Then the fluorinated carbon nanotubes were separated by dissolving the alumina film with HF. A schematic drawing of the fluorination process is given in Fig. 10.1.15. 

Reaction conditions, compositions and XRD data of fluorinated carbon nanotubes... 

The reaction of fluorinated carbon nanotubes with alcoholates yields ether-bridged stmctures. The analogous reaction with primary amines provides species... 

In a like manner fluorinated carbon nanotubes and fibers can be formed. These materials are the subject of a great deal of interest, owing in part to their variable electronic properties. ... 

Fedoseeva, Y. V., Bulusheva, L. G., Okotrub, A. V., Vyalikh, D. V., Fonseca, A. 2010. High reactivity of carbon nanotubes and fluorinated carbon nanotubes irradiated by Ar+ ions. Phys. Status Solidi B 247 (11-12) 2691-2694. 

Li Y, Chen YF, Feng YY, Zhao SL, Lii P, Yuan XY, Feng W (2012) Progress of synthesizing methods and properties of fluorinated carbon nanotubes. Sci China Technol Sci 53(5) 1225-1233... 

Conductivity of the anode is important to MF C performance. One method that has been suecess-fully used to increase conductivity and current densities of MFC is the application of the eonductive polymer polyaniline (Schroder etal., 2003). However, performance was only improved temporarily as polyaniline was shown to be unstable and susceptible to microbial degradation (Niessen et al., 2004). While these findings would seemingly limit polyaniline s potential contribution to future MFC designs research has suggested that it may be possible to improve both the stability and performance of polyaniline by making composites combined with fluorine, carbon nanotubes (Qiao et al., 2007) and titanium dioxide (Qiao et al., 2008). 

Gu Z, Peng H, Hauge RH, Smalley RE, Margrave JL (2002) Cutting single-wall carbon nanotubes through fluorination. Nano Lett. 2 1009-1013. 

The fluorination of carbon nanotubes was first reported by Margrave and is traditionally performed by using elemental fluorine in the presence of small amounts of HF which serves as catalyst [24]. The loading turns out to be very high, with one fluorine atom every two carbon atoms. 

Fig. 3.7 Fluorination and further substitution of pristine carbon nanotubes.

Taking into consideration that only the inner wall surface of carbon nanotubes is exposed to atmosphere in the stage of carbon-deposited alumina film, it would be possible to modify only the inner surface if the carbon-deposited alumina film is chemically treated. On the basis of this concept, Hattori et al. tried to fluorinate only the inner surface of carbon nanotubes (42). It is well known that fluorination is quite an effective way to introduce strong hydrophobicity to carbonaceous materials, and it perturbs the carbon it electron system (43,44). Thus, by the selective fluorination of nanotube s inner surface, it would be possible to produce carbon nanotubes whose inner surface is highly hydrophobic and electrically insulating while their outer... 

Fig. 10.1.15 Schematic diagram of the fluorination process of carbon nanotube.

Fig. 10.1.17 Cls XPS spectra of (a) the fluorinated carbon deposited film and (b) the carbon nanotubes from the film (fluorination temperature 175°C). (From Ref. 42.)...

In order to examine the chemical state on the carbon surface, x-ray photoelectron spectroscopy (XPS) analysis was performed for both the fluorinated carbon-coated AAO film and the liberated nanotubes from this fluorinated film. In the resulting XPS Cls spectrum of the fluorinated film (Figure 3.11a), the most intense component is the peak assigned to the covalent C-F bond (about 290eV),... 

The fluorinated carbon-coated AAO film has an interesting adsorption characteristic that has not been reported so far. Figure 3.12 shows N2 adsorption/desorption isotherms at -196°C for the pristine carbon-coated AAO film and the films fluorinated at different temperatures [119]. The isotherm of the pristine film is characterized by the presence of a sharp rise and a hysteresis in a high relative pressure range. Such a steep increase can be ascribed to the capillary condensation of N2 gas into the nanochannels of the AAO films, that is, the inner space of the nanotubes embedded in the AAO films. The amount of N2 adsorbed by the condensation into the fluorinated channels is lower than that of the pristine one. Moreover, the amount drastically decreases with an increase in the severity of fluorination. Since TEM observation revealed that the inner structure of the fluorinated CNTs was not different from that of the pristine nanotubes, the reason why the N2 isotherm was so changed as in Figure 3.12 cannot be attributed to the alteration of the pore texture upon the... 

Hattori, Y., Watanabe, Y., Kawasaki, S., Okino, F., Pradhan, B.K., Kyotani, T., Tomita, A., and Touhara, H. Carbon-alloying of the rear surfaces of nanotubes by direct fluorination. Carbon 37, 1999 1033-1038. 

BINDING OF A FLUORINE ATOM TO THE SIDEWALL OF SINGLE-WALLED CARBON NANOTUBES... 

Finally, gold-plated copper turnings catalysed the fluorination of aromatic hydrocarbons at 550K 20 gold has also been the means of making carbon nanotubes from ethyne (5% Au/SiC -A Cfy 823 K)21 and chloromethylsilanes.22... 

Jaffe RL (2003) Quantum chemistry study of fullerene and carbon nanotube fluorination. J. Phys. Chem. B 107 10378-10388... 

Fig. 5. TEM image of carbon nanotube fluorinated at room temperature, Stage 1 C5 3F (reproduced with permission from Eur. J. Solid State Inorg. Chem., 33 (1996) 831 [27]).

Fullerene Cgo is easily fluorinated by elemental fluorine at temperatures less than 100°C [29,30] probably because of its nearly spherical surface and exposed it bonding. Direct fluorination of organic compounds by fluorine gas demonstrated that fluorine was preferentially bonded to a carbon atom with a high electron density [31,32], This may be a main reason why fullerene C60 is more easily fluorinated than graphite. On the contrary, the fluorination behavior of carbon nanotube is similar to that of graphite as already shown. 

---