Electrodepositions and capacitive properties of hybrid films of polyaniline and manganese dioxide with fibrous morphologies

Electrocodepositions were conducted in solutions of aniline and MnSO4 through potential cycling to afford hybrid films of polyaniline (PANI) and manganese dioxide (PANI/MnO2). The films obtained displayed characteristic redox peaks of PANI on cyclic voltammograms in acidic aqueous solution. While in 1.0 M NaNO3 at pH 1, the films showed pseudocapacitive behaviors from 0 to 0.65 V vs. SCE. MnO2 was detected through XRD and XPS measurements on the films. The codeposition of PANI with MnO2 had dramatic effects on morphologies of the obtained hybrid films that displayed fibrous morphologies instead of granular one of PANI. Hybrid film PM50 obtained in the presence of 50 mM Mn2+ displayed a specific capacitance of 532 F g−1 at 2.4 mA cm−2 discharging current, 26% higher than that of similarly prepared PANI. It showed a coulombic efficiency (η) of 97.5% over 1200 cycles with 76% specific capacitance maintained.