Mechanism of Reductive C60 Electropolymerization in the Presence of Dioxygen and Application of the Resulting Fullerene Polymer for Preparation of a Conducting Composite with Single-Wall Ca

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• 作者：Piotr Pieta ; Grazyna Z. Zukowska ; Sushanta K. Das ; Francis D’ ; Souza ; Andreas Petr ; Lothar Dunsch ; Wlodzimierz Kutner
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：May 13, 2010
• 年：2010
• 卷：114
• 期：18
• 页码：8150-8160
• 全文大小：538K
• 年卷期：v.114,no.18(May 13, 2010)
• ISSN：1932-7455

文摘

The superoxide anion radical, O₂^•−, induced C₆₀ electropolymerization mechanism was refined by simultaneous cyclic voltammetric (CV) and vis-NIR spectroelectrochemical as well as mass spectrometric (MALDI-TOF) characterization of the one- and two-electron reduction products of C₆₀ in the presence of O₂ in a mixed organic solvent solution. The C₆₀ polymer (C₆₀-O) film was also investigated by Raman spectroscopy and imaged by atomic force microscopy (AFM) both at the early and advanced polymerization stage. While the spectroelectrochemical behavior of the C₆₀/C₆₀^•− couple in the presence of O₂ was similar to that in its absence, at more negative potentials corresponding to C₆₀²⁻ and O₂^•− formation C₆₀²⁻ participated in a chemical follow-up reaction resulting in a product lacking any diagnostic absorption band in the vis-NIR range. Although the main peak in the MS spectrum of the one-electron reduction product was that of C₆₀ at m/z of 720, several additional peaks in the m/z range of 739−760 appeared, indicating generation of C₆₀O^•− and C₆₀O₂^•− followed by their protonation. Interestingly, the MS spectrum of the product of two-electron reduction of C₆₀ revealed several peaks in the m/z range of 1297−1465. These peaks correspond to the oxygen-containing fullerene protonated dimers, which lose the C_n (n = 1, 2) or C_2n (n = 2−5) fragments upon ionization. Apparently, products of the C₆₀²⁻ and O₂^•− interaction spontaneously dimerize in the electrode vicinity. Importantly, oxygen is built into the dimeric molecule in the initial stage of electropolymerization. The Raman spectroscopy measurements and AFM surface imaging of the C₆₀-O film revealed that the first CV cycle resulted in an electrodeposition of dimers. With the increase of the number of CV cycles, the extent of polymerization increased and the polymer structure became highly heterogeneous. Finally, an electrophoretically deposited film of the HiPCO single-wall carbon nanotubes (pyr-SWCNTs) noncovalently surface modified with 1-pyrenebutyric acid was coated by electropolymerization with the C₆₀-O film under CV conditions to result in a polymer−CNT composite material. AFM imaging of this film showed that tangles of the pyr-SWCNTs bundles, coated with the C₆₀-O globules, were formed. The electrochemical and viscoelastic properties of the pyr-SWCNTs|C₆₀-O film were unraveled by simultaneously performed CV and piezoelectric microgravimetry (PM) measurements in a blank (TBA)ClO₄ acetonitrile solution. Specific capacitance of the electrode coated with this composite film was 184 F g⁻¹, a value comparable to those for other SWNT composite film coated electrodes, suggesting a plausible application of this material in developing supercapacitors.