Investigation on the electrochemical performance of hausmannite Mn3O4 nanoparticles by ultrasonic irradiation assisted co-precipitation method for supercapacitor electrodes

Spinel type manganese oxide (Mn3O4) nanoparticles were synthesized by ultrasonic irradiation assisted co-precipitation method using PEG and NaOH. The formation of tetragonal hausmannite phase (Mn3O4) with spinel structure was confirmed from XRD and FTIR studies. The average crystallite size of Mn3O4 nanoparticles was determined from Scherrer formula (39.9 nm) and Williamson–Hall relation (36.5 nm). The presence of elements, the overall oxidation state of manganese (Mn2+, Mn3+ and Mn4+) and chemical composition of these nanoparticles were determined from Mn 2p, Mn 3s and O 1s spectra using XPS. The spherically shaped morphology of these nanoparticles was analysed by SEM. The expected chemical composition of Mn3O4 nanoparticles was analysed by EDS. The electrochemical performance of these Mn3O4 nanoparticles was studied by CV, CP and AC impedance analysis. The maximum specific capacitance of Mn3O4 nanoparticles was found to be 296 F/g at a current density of 1 A/g2. Nyquist plot shows lower value of resistance that indicates the good electrical conductivity of the Mn3O4 electrode, which accounts for the improved electrochemical performance of the supercapacitors. Hence, the use of surfactant and the presence of ultrasonic irradiation in the synthesis process plays a dominant role in the electrochemical performance of Mn3O4 supercapacitors