ELECTRODEPOSITION AND ELECTROCHEMICAL-BEHAVIOR OF PALLADIUM PARTICLES AT POLYANILINE AND POLYPYRROLE FILMS

The electrodeposition of palladium particles at electronically insulating polyaniline and conducting polypyrrole films in aqueous solution has been investigated. The number density of particles and their overall surface area was calculated from current transients recorded during deposition at constant potential. Both were found to depend strongly on the palladium deposition overpotential. Hydrogen adsorption and desorption, as well as hydrogen evolution, were found to take place readily on the palladium particles at polyaniline in its reduced, electronically insulating, state. Hydrogen oxidation, however, was only observed concurrently with oxidation of polyaniline to its electronically conducting state. Oxygen reduction was found to occur on Pd-loaded polyaniline films at higher rates than similarly loaded vitreous carbon electrodes, due to larger real surface area of Pd obtained at polyaniline.