Voltamperommetric study of chemically made polyaniline powder with cavity microelectrode technique

Chemically synthesized polyaniline powder (PANi) was investigated with a cavity microelectrode (CME) in aqueous electrolyte. With this technique, it is shown that high scan rates (up to 400 V s−1) can be reached even if working on powder materials. Thus, a complete voltammetric study was done on PANi powder and our results were compared with literature data, especially those obtained by working on thin films. The electrochemical behavior of the PANi powder with such a microelectrode is found to be similar to the one of a thin film material with a kinetic constant for the electronic transfer close to 8 s−1 and a charge transfer coefficient of 0.46. A detailed mechanism is then proposed to explain first, the different shapes observed during the oxidation and reduction reactions, and second, the evolution of kinetic parameters (peak intensity, peak potential, and exchanged charge) versus the scan rate. The peak broadening for scan rates higher than 10 V s−1 is explained with the help of electrode polarization.