Polythiophene, polyaniline and polypyrrole electrodes modified by electrodeposition of Pt and Pt+Pb for formic acid electrooxidation

The electrosynthesis of polythiophene (PTh), polyaniline (PANI) and polypyr role (PPy) films modified by dispersion of Pt or Pt + Pb and its employment in the electrocatalytic oxidation of HCOOH are studied and compared. The i nfluence of parameters such as polymer film thickness, the number of disper sed Pt particles, the amount of Pb deposited and the presence of Pb2+ in th e electrolyte on the electrooxidation of HCOOH is investigated. Electrode s ystems including the polymer and a mixture of Pt and Pb particles show a be tter electrocatalytic activity than electrodes having a polymer-Pt combinat ion or bulk Pt electrodes. Furthermore, during the electrooxidation of HCOO H using polymer-(Pt + Pb) electrodes the presence of fewer poisoning specie s is observed, indicating that the role of Pb in these electrode systems is in agreement with the Pb adatom effect observed when bulk Pt electrodes ar e used. However, the presence of Pb(rr) in the electrolyte is not required for the PTh-(Pt + Pb) electrode system and, in addition, a better electroca talytic effect is obtained in this case. With application of an appropriate E/t program the activity is unchanged over a long time.