Films of single-wall carbon nanotubes (SWCNTs) were cast from suspensions in several solvents on the surface of a Pt or Au electrode. Cyclic voltammetry of the films in MeCN did not show well-resolved waves (as distinct from films of C 60 prepared in a similar manner). However, the increase in the effective capacitance of the electrode with a SWCNT film at 0.5 V vs. an AgQRE was 283 F/g, which is about twice that of carbon electrodes in nonaqueous solvents. © 1999 The Electrochemical Society. S1099-0062(99)06-057-5. All rights reserved.Manuscript submitted June 9, 1999; revised manuscript received July 30, 1999. Available electronically September 7, 1999.We describe here, for the first time, studies of thin films of single-wall carbon nanotubes (SWCNT) deposited on Pt or Au electrode surfaces and their voltammetric response. SWCNTs are interesting materials, since their electronic properties are significantly modulated by slight structural variations in diameter and the helicity of the carbon atoms in the wall. 1,2 We were interested in comparing the behavior of such SWCNT films with those of the fullerenes, C 60 and C 70 . 3,4 We show that, while these films give no distinct voltammetric peaks, probably because of a broad tube size distribution, they show a very high "effective capacitance" which might make them of interest as electrodes in supercapacitors.Films of the fullerenes can be cast from solutions of C 60 or C 70 in benzene or other solvents. However, SWCNTs are insoluble in all solvents; therefore films had to be cast from SWCNTs in benzene, acetonitrile (MeCN), acetone, or water containing sodium dodecylsulfate (SDS, 0.5 g in 100 mL) after strong sonication. A greater amount of SWCNTs could be dispersed in SDS solution than in other solvents due to the self-aggregation of surfactant molecules into micelles. Thin films of SWCNTs c were prepared by evaporation on a Pt or Au electrode surface of a few microliters of a suspension similar to a procedure used for the C 60 studies. 3,4 When the thin films were cast from SDS solutions, the electrodes were kept in an oven (104°C) for about 45 min before transfer into a dry box where electrochemical experiments were conducted in MeCN under a helium atmosphere. A CH Instruments model 660 was employed for the cyclic voltammetric (CV) measurements in MeCN solutions containing 0.1 M tetra-n-butylammonium hexafluorophosphate (TBAPF 6 ). A platinum mesh served as the counter electrode, and a silver wire was used as a quasi-reference electrode.Films prepared from C 60 suspensions were studied first to compare their CV characteristics to those films prepared from solutions of C 60 in benzene, which produce well-defined waves. These C 60 suspensions in solvents like water/SDS and MeCN produced films that showed essentially identical CV behavior to those cast from solutions (Fig. 1). For example, the reduction C 60 j C 60 -j C 60 2-and corresponding oxidation peaks were well-defined over the given potential region. A third reduction wave (not shown) was observed at more...

Individual members of a family of highly absorptive porphyrins bearing symmetrically positioned flexible side chains form discotic liquid crystalline mesophases at modest temperature ranges. The order of this phase is preserved when a thin layer of this self‐assembled material is cooled to room temperature. Exposure of such films to visible excitation, with or without an externally applied electrical field, produces photovoltaic effects and/or charge trapping. The latter effect constitutes the basis for optoelectronic information storage.

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