Single-step synthesis of Mn3N2, MnxON and Mn3O4 nanoparticles by thermal plasma arc discharge technique and their comparative study as electrode material for supercapacitor application

Abstract

In the present study, single-step synthesis of single-phase manganese nitride (Mn3N2), mixed phase manganese oxynitride (MnxON) and manganese oxide (Mn3O4) nanoparticles (NPs) was carried out using the thermal plasma arc discharge (TPAD) method. The experiments were carried out using nitrogen (N2), ammonia (NH3) and oxygen (O2) gas atmospheres at different plasma powers 2, 4 and 6 kW. The phase and elemental compositions of the prepared nanoparticles were examined using X-Ray Diffraction (XRD) and Energy Dispersive X-ray Spectroscopy (EDX) analysis. All the synthesized powder samples have nearly spherical morphology, which are determined by using Field Emission Scanning Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis. The surface area of the prepared NPs was investigated using Brunauer-Emmett-Teller (BET) analysis, and the obtained results are 40.1, 19.4 and 11.8 m2g−1 for Mn3N2, MnxON and Mn3O4 NPs respectively. The Mn3N2 NPs showed superior storage performance with an outstanding specific capacitance of 508.4 F/g at 1 A/g with pseudocapacitive behavior compared to the mixed and oxide NPs 335.1 and 150 F/g respectively. The Mn3N2 electrode exhibited higher cycling stability with 84.2% capacitance retention after 5000 cycles at a current density of 5 A/g. These results demonstrated that the plasma-prepared single-phase Mn3N2, which is used as a potential electrode material for supercapacitors applications.