Abstract: Conductive and functional polypyrrole (PPy) film was prepared by incorporation of anthraquinonesulphonate (AQS) as dopant during the electropolymerization of pyrrole on a glassy carbon electrode in aqueous solution. The electrochemical behavior of AQS in PPy matrix in various pH buffer solutions and electrocatalytic reduction of oxygen on the resulting polymer film at the optimized pH of 5.5 were studied by using cyclic voltammetry (CV) and rotating disk electrode (RDE) technique. The results showed that PPy not only lowed the AQS reaction potential and the peak potential separation but also increased the redox peak currents. The value of ionization constant for H2AQ/HAQ- is 9.5. The CV and RDE studies showed the involvement of two electrons in oxygen reduction and H2AQ is responsible for the enhanced catalytic activity. The catalytic reaction is in agreement with an electrochemical-chemical mechanism. The AQS/PPy composite film-modified electrode was found to exhibit reproducible results.

Key words: anthraquinonesulphonate, polypyrrole, modified electrode, oxygen reduction, electrochemistry, electrocatalysis