Hydrothermal growth of magnesium ferrite rose nanoflowers on Nickel foam; application in high-performance asymmetric supercapacitors

Herein, for the first time, magnesium ferrite rose nanoflowers (MFRNs) were directly grown on nickel foam through a facile two-step hydrothermal and post-annealing method. FESEM studies showed that MFRNs have a micro to nano architecture from microflower bundles to nanopetals. The rose flowers consist of sheet-like petals with a thickness of 22–44 nm. A mechanism was proposed for the growth of nanostructures, and then they were studied by different electrochemical techniques of cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) for possible application in supercapacitor electrodes. The MFRNs/NiF electrode showed a specific capacitance of 240 F g⁻¹ (or 121 mF cm⁻²) at a scan rate of 20 mV s⁻¹. Furthermore, the charge–discharge voltammetric studies showed that the excessive cycling not only does not lead to performance degradation but higher capacitances due to enhanced contribution of the pseudocapacitor. Lastly, the electrode performance was tested in two-electrode configuration and it proved a promising electrode in asymmetric supercapacitors.