In situ electrodeposition of conducting polymer/metal oxide composites on iron electrode for energy storage applications

Conducting polymers and their metals or metal oxides-based composites are promising for applications in aerospace engineering, construction, computer chips, electronic circuits, energy storage systems, catalysis of reaction and so on. Supercapacitor electrodes and devices comprising polymers/metal oxides composites are envisaged to bridge the gap between existing carbon-based supercapacitors and batteries to form units of intermediate specific energy. In this work, polyaniline (PAni) and its composite with MnO2 were successfully deposited by electrochemical method. Simultaneous polymerization of aniline to PAni, and in situ formation and incorporation of MnO2 into the PAni matrix, and their deposition on Fe substrate took place during the cycling of potential in oxalic acid solution containing aniline and a salt of manganese. Elemental characterization and investigation of morphology and microstructure of the deposits were performed by infra-red, UV–visible reflectance and energy dispersive X-ray spectroscopy and scanning electron microscopy. The band gap energy of PAni was substantially higher compared to PAni/MnO2 composite. The specific capacitance of the electrodes prepared was investigated using cyclic voltammetry and charge–discharge test by chronopotentiometry. Fe-PAni and Fe-PAni/MnO2 composite modified electrodes exhibited excellent supercapacitive property, energy density and power density compared to their bulk Fe electrodes in aqueous sodium sulfate solution.