COMPARATIVE-EVALUATION OF ELECTRODEPOSITION OF POLYPYRROLE ON LEAD-DIOXIDE-COATED GLASSY-CARBON AND OF LEAD DIOXIDE ON POLYPYRROLE-COATED GLASSY-CARBON ELECTRODES

Electrodeposition of lead dioxide and polypyrrole on glassy carbon, of lead dioxide on polypyrrole-coated glassy carbon, and of polypyrrole on lead-dioxide-coated glassy carbon electrodes was carried out by a potentiodynamic method. The morphological features of each phase were studied using scanning electron microscopy (SEM). The electrochemical activity of the phase was evaluated using cyclic voltammetry. It was found that polypyrrole-coated glassy carbon is relatively less active than lead-dioxide-coated glassy carbon electrodes with regard to further deposition on these surfaces. SEM and cyclic voltammetric studies reveal that polypyrrole growth takes place uniformly on both lead dioxide nuclei and bare glassy carbon surfaces in the case of lead-dioxide-coated glassy carbon electrodes. However, electrodeposition of lead dioxide on polypyrrole-coated glassy carbon proceeds only on active polypyrrole hemispheres, although a substantial portion of the bare glassy carbon substrate is still available for deposition. The exclusion of the bare glassy carbon surface from further deposition of lead dioxide on polypyrrole-coated glassy carbon electrode may be due to the initial growth of an invisible passive two-dimensional polypyrrole layer.