Effect of Substrate on Polyaniline Film Properties A Cyclic Voltammetry and Impedance Study

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Abstract
The electrochemical properties of polyaniline (PANI) films, grown using multicycling methods, but using two different upper limits, have been examined in detail at three different substrates [Au, Pt, and glassy carbon (GC)]. Overall, type I films are only weakly dependent on the substrate employed. Even so, impedance measurements have shown that type I PANI films (grown by cycling between 0 and ca. 1 V in ), formed on Pt and Au, exhibit the most rapid growth rate, while the highest film pseudocapacitance per unit charge is seen for Pt substrates. Type I PANI has a porosity of 45–50% when formed on Pt and Au, but the porosity is much higher (ca. 77%) on GC, inversely correlated with film growth rate. The substrate has a more pronounced effect on the electrochemical properties of type II PANI films (grown by cycling between 0 and 1.7 V in solution). This is because type I films are formed at potentials at which PANI is conducting, while type II are formed primarily when PANI is insulating. Therefore, type I film growth occurs predominantly at the conducting PANI/solution interface, while growth of type II films occurs primarily at the underlying metal/solution interface, causing the substrate properties to become more significant. The growth rate of type II PANI is most rapid on GC, due to the absence of a barrier oxide film, vs. on Pt and Au. © 2000 The Electrochemical Society. All rights reserved.

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