Double layer and redox capacitances of polyaniline electrodes in aqueous trichloroacetic acid

The high and low frequency capacitances of the polyaniline layer in contact with aqueous electrolyte (0.5 M CCl3COOH) were analyzed as a function of the redox slate of the polymer, temperature, and a polymer film thickness. The corresponding double layer and redox capacitances were discussed in terms of physical models, and some relevant parameters were determined. Furthermore, the middle frequency adsorption capacitance was shown to contribute to the electrical/electrochemical characteristics of the polymer electrode. The magnitude and dynamics of changes in the double layer and adsorption capacitances due to redox/conductivity state switching of polyaniline were characterized using the LH function approach. The redox capacitances of the conducting polyaniline are of the order of 10(2)-10(3) F cm(-3). This is by factors of the order of 10(1) and 10(2) higher than the adsorption and double layer capacitances, respectively. (C) 1999 The Electrochemical Society. S0013-4651(98)05-93-9. All rights reserved.