Investigation of pseudocapacitance effect and frequency dependence of ac impedance in polyaniline–polyoxometalate hybrids

In polyaniline (PAni) prepared by interfacial polymerization, the conductivity increases with temperature due to the heating induced molecular arrangement which is favorable for charge delocalisation. The hydroxyl groups present in the polyoxometalates-doped PAni hybrids play a vital role in the conductivity mechanism of these materials. The appearance of pseudocapacitance loop at low frequency region is due to the temperature-assisted formation of oxonium ions and the protonation of polymer by this at the electrode–electrolyte interface and it is in agreement with the TGA studies. From the frequency dependant conductivity measurements at high temperatures, it is found that, PAni obeys the correlated barrier hopping model whereas its hybrids follow overlapping large polaron tunneling model.