Electrochemical synthesis of polypyrrole films on copper electrodes in acidic and neutral aqueous media

The use of appropriate electrolyte allows to deposit Polypyrrole (PPy) films on oxidizable metals such as copper by electrochemical oxidation of Pyrrole. In this work, oxalic acid, sodium oxalate, sodium/potassium tartrate and sodium salicylate are used as electrolytes and compared in terms of easiness for polypyrrole deposition, and film characteristics. Electrochemical measurements in presence of these electrolytes with and without pyrrole demonstrate that copper can be efficiently passivated before polypyrrole electrodeposition. Moreover, FT-IR experiments reveal the chemical constitution of the thin passivating layer formed prior to the pyrrole electropolymerization and preventing copper corrosion without inhibiting the polymer formation: in oxalic acid medium, the presence of Cu(I) oxalate is clearly evidenced as the only passivating agent, whereas the weak transmission intensities of the spectra obtained with samples polarized in oxalate and tartrate media suggest thin layers thus non-fully identified and the salicylate medium is the only one for which one can distinguish successively the formation of the thin layer constituted of copper (II) ions complexed by the salicylate anion and then, the formed polypyrrole.