Manganese oxide embedded polypyrrole nanocomposites for electrochemical supercapacitor

MnO2 embedded PPy nanocomposite (MnO2/PPy) thin film electrodes were electrochemically synthesized over polished graphite susbtrates. Growing PPy polymer chains provides large surface area template that enables MnO2 to form as nanoparticles embeded within polymer matrix. Co-deposition of MnO2 and PPy has a complimentary action in which porous PPy matrix provides high active surface area for the MnO2 nanoparticles and, on the other hand, MnO2 nanoparticles nucleated over polymer chains contribute to enhanced conductivity and stability of the nanocomposite material by interlinking the PPy polymer chains. The MnO2/PPy nanocornposite thin film electrodes show significant improvement in the redox performance as cyclic voltarnmetric studies have shown. Specific capacitance of the nanocomposite is remarkably high (similar to 620 F g(-1)) in comparision to its constituents MnO2 (similar to 225 F g(-1)) and PPy (similar to 250 F g(-1)). Photoelectron spectroscopy studies show that hydrated manganese oxide in the nanocomposite exists in the mixed Mn(II) to Mn(IV) oxidation states. Accordingly, chemical structures of MnO2 and PPy constituents in the nanocornposite are not influenced by the co-cleposition process. The MnO2/PPy nanocornposite electrode material however shows significantly improved high specific capacitity, charge-discharge stability and the redox performance properties suitable for application in the high energy density supercapcitors. (C) 2008 Published by Elsevier Ltd.