Electroless silver deposition on polypyrrole and poly(3,4-ethylenedioxythiophene): The reaction/diffusion balance

Processes of spontaneous metallic silver deposition from AgNO3 solutions on electrodes coated by semi-oxidised conducting polymers: polypyrrole and poly(3,4-ethylenedioxythiophene) were studied. Kinetic information was obtained from open circuit potential transients, showing that for slightly oxidised polymers in quiescent solution the rate of Ag(I) reduction is dependent on Ag(I) ion diffusion in solution. In stirred solutions or for more oxidised polymers the initial step of the process is controlled by new phase (Ag on conducting polymer) formation, as shown using rotating disk electrode voltammetry. The influence of Ag(I) concentration, conditioning time, kind of polymer and its thickness on the amount of accumulated silver was analysed. The reaction-diffusion balance determines where the silver is deposited in the polymer. Although both polymers can be penetrated by Ag+ ions, the highest amount of Ag is detected on the polymer surface, as laser ablation coupled with mass spectrometry experiments has shown.