The formation of polypyrrole at iron from 1-butyl-3-methylimidazolium hexafluorophosphate

The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, was used to deposit adherent and highly conducting polypyrrole coatings at pure iron using a simple potentiostatic technique. Adherent and highly conducting polypyrrole films were formed at the iron substrate using potentials in the range from 1.0 to 1.4 V and with pyrrole concentrations between 0.1 and 0.3 mol dm(-3). An increase in the applied potential, or the concentration of the monomer, gave rise to an increase in the rate of polymer growth. The polypyrrole-coated iron electrodes were electroactive and remained highly conducting and stable in the ionic liquid. Using electrochemical impedance spectroscopy, the charge-transfer resistance of the uncoated iron electrode was determined as 1.25 x 10(4) Omega cm(2) compared to the much lower resistance of 1.90 x 10(2) Omega cm(2) measured for the highly conducting polypyrrole-coated electrode in the ionic liquid. (C) 2004 The Electrochemical Society.