A growth mechanism investigation on the anodic deposition of nanoporous gold supported manganese oxide nanostructures for high performance flexible supercapacitors

Abstract

A detailed study of the growth mechanism of manganese oxides nanostructures grown on nanoporous gold films (NPG) was carried out. A thin layer of manganese oxide nanostructure was uniformly plated into the nanopores of NPG by anodic deposition from a dilute solution of Mn(CH3COO)2 (manganese acetate) onto polyethylene terephthalate (PET) flexible films. The morphology of the electrodes depended on the deposition current density, which greatly influenced the electrochemical performance of the capacitor. The investigation of growth mechanism of such manganese oxides/nanoporous gold (MnOx/NPG) hybrid electrodes configuration revealed that smaller current density acts on NPG for the oxidation reaction of Mn2+ ion and easy nucleation of the manganese oxide acts on the chemically active internal surface of NPG substrate. Compared with continuous coating of MnOx/Au electrodes, the morphology for manganese oxides grown on NPG substrates tends to be open and porous nanostructure in a wider range of electrodeposition current density. Electrochemical analysis of MnOx/NPG nanostructured electrodes revealed that they exhibited higher capacitance and low charge transfer resistances. In addition, the low deposition current densities studied (0.05 and 0.1 mA cm−2) for a thin nanowire and fibrous morphology exhibited enhanced electrochemical performance. The largest value obtained was 432 F g−1 for deposits at 0.1 mA cm−2.