Phase evolution of electrodeposited manganese oxide for supercapacitor applications

Abstract

Energy is of paramount importance in our everyday lives and energy storage technologies are needed to solve the global energy problems largely. In this work, manganese oxide (MnxOy) films were electrodeposited chronoamperometrically on stainless steel (ss) and fluorine doped tin oxide (FTO) substrates at different step potentials. The effect of the deposition potential and temperature treatment on the phase and supercapacitive properties of the MnxOy were studied. At a step potential of less than 1.2 V no deposition was achieved while at 1.2 V, the as deposited oxide showed a bit of amorphousness with vestiges of Mn(OH)2 as evident from the x-ray diffraction (XRD) studies. At higher potentials (1.4 and 1.6 V), the as-deposited oxide appeared as the MnO2 phase. However, higher temperature treatment (600 °C) of all the deposits obtained at the various potentials resulted to Mn2O3 phase. The scanning electron microscopy (SEM) of the films showed that the as-deposited and the 400 °C annealed electrodes are porous while they become more compact and cemented at 600 °C. The obtained bandgap energies ranged from 1.26–2.65 eV for the films deposited at differing potentials and heat treatments. The electrochemical analysis shows the highest specific capacitance of 455 F g−1 for the 1.2 V@400 °C electrode while the Mn2O3 electrodes are more stable. The electrodes exhibited good potentials for supercapacitor application. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.