Preparation and selected properties of composites of the C60-Pd conducting polymer and soluble single-wall carbon nanotubes
|Piotr Pieta 1, Emilia Grodzka 2, Krzysztof Winkler 2, Francis D'Souza 3, Wlodzimierz Kutner 1|
1. Polish Academy of Sciences, Institute of Physical Chemistry, Kasprzaka 44/52, Warszawa 01-224, Poland
A composite thin film of the novel electroactive fullerene-palladium (C60-Pd) polymer and single-wall carbon nanotubes, which were non-covalently modified by 1-pyrenebutiric acid (pyr-SWCNTs), was electrochemically prepared under multi-scan cyclic voltammetry (CV) conditions and its conductive, capacitance and visco-elasitic properties investigated. The film was prepared by using a mixed C60, pyr-SWCNTs, and palladium acetate solution of either mixed acetonitrile : toluene (1 : 4, v : v) or 1,2-dichlorobenzene solvent. A tetrabutylammonium salt, like 0.1 M (TBA)ClO4 or (TBA)PF6, was used as a supporting electrolyte. Mass changes of the deposited composite film were measured in situ by piezoelectric microgravimetry with the use of an electrochemical quartz crystal microbalance. The quartz crystal resonators with their electrodes coated by either the C60-Pd or C60-Pd/pyr-SWCNTs composite film were transferred to a blank supporting electrolyte solution, i.e., 0.1 M (TBA)ClO4 or (TBA)PF6 in acetonitrile, and current, resonance frequency changes, and dynamic resistance changes vs. scanned potential were simultaneously recorded in different potential ranges. Each polymer revealed electrochemical activity at potentials more negative than ca. -0.7 V. Both cathodic and anodic currents for the C60-Pd/pyr-SWCNTs films were almost twice as high as those for the C60-Pd films. The presence of pyr-SWCNTs in the polymer causes an increase of the electrode capacitance, as manifested by increased CV current. For the potential range 0 to -1.2 V changes of both resonance frequency and dynamic resistance are almost the same for the C60-Pd and C60-Pd/pyr-SWCNTs films. Distinct differences are seen, however, for potentials exceeding -1.2 V. That is, frequency rapidly decreases when the potential reaches the -1.2 V value in the negative excursion. However, this decrease is three times smaller for the C60-Pd/pyr-SWCNTs film than that for the C60-Pd film. This decrease of frequency is accompanied by the increase of dynamic resistance. Changes of dynamic resistance for the C60-Pd film are three times larger than those for the C60-Pd/pyr-SWCNTs film. This behavior suggests that for potentials more negative than -1.2 V the C60-Pd/pyr-SWCNTs film is more rigid than the C60-Pd film. Moreover, redox conductivity of the C60-Pd films doped with pyr-SWCNTs is higher than that of the undoped C60-Pd films. The redox conductivity values, determined from the highest slopes of the rising portions of cathodic CV curves in the range ca. -0.6 to -0.8 V, are 0.92 and 1.48 mS for the film of the C60-Pd and the C60-Pd/pyr-SWCNTs composite, respectively. In the Raman spectrum for the C60-Pd/pyr-SWCNTs film there are peaks characteristic both for pyr-SWCNTs (radial breathing modes, RBM) and C60-Pd indicating that, indeed, pyr-SWCNTs are incorporated into the film during electropolymerization of C60-Pd. Moreover, the RBM peaks for the pyr-SWCNTs film are deconvoluted in the spectrum of the composite due to different extent of aggregation of pyr-SWCNTs.
Presentation: Poster at SMCBS'2007 International Workshop, by Piotr Pieta
See On-line Journal of SMCBS'2007 International Workshop
Submitted: 2007-10-17 15:58 Revised: 2009-06-07 00:48