Behaviour of poly(pyrrole) and poly(N‐methylpyrrole) electrodes in acetonitrile

The impedance of poly(pyrrole) (PP) and poly( N ‐methylpyrrole) (PMP) films on platinum in an acetonitrile, LiClO 4 solution has been measured. At potentials more positive than a characteristic value, the electrodes exhibit porous behaviour and the impedance is determined by the double‐layer capacitance and the solution resistance inside the pores. At more negative potentials, the PP and PMP electrodes behave like flat‐plate electrodes and two impedance contributions can be distinguished, i.e. a material contribution (material resistance and material capacitance) and a contribution from the interphase polymer‐electrolyte (faradaic resistance and double‐layer capacitance).