Electrocatalytic activity of polypyrrole films incorporating palladium particles

This work exploits the electroless precipitation approach for the incorporation of palladium in polypyrrole (PPy). Electrochemical and morphological analysis of PPy films prepared on Pt, under potentiostatic and potentiodynamic control, reveal the influence of the electrosynthesis conditions on the bulk and surface properties of the polymer. It is shown that, besides the pH of the PdCl2 containing solutions, those PPy characteristics play an important role on the rate of the Pd uptake process. The resulting Pd(0)/Pdox ratio, size and surface distribution of the metallic particles on the film surface are analysed in detail and correlated to the electrocatalytic activity disclosed by the modified PPy electrodes towards the oxidation of hydrazine in KCl solution. In comparison to palladium thin coatings, a superior behaviour is achieved for PPy rough surfaces able to create uniform dispersions of sub-micron Pd particles, but the employment of polymer films with less coarse surfaces and/or an increasing in the amount and size of the Pd particles is disadvantageous for catalytic purposes.