Green fabrication of NiFe₂O₄@rGO nanocomposites for efficient electrochemical energy storage

To meet the demands for sustainable and eco-friendly energy sources, researchers are focusing on the green synthesis of novel nanomaterials for energy storage. In the present study, nickel ferrite nanoparticles (NiF-NPs) were synthesized from the Fagonia arabica plant extract, followed by the formation of nickel ferrite nanocomposites with rGO (NiF-NCs). Structural characterization was performed by XRD, FTIR spectroscopy, SEM and EDX techniques. The electroanalytical tools, namely, CV, GCD and EIS, were employed to investigate the electrochemical properties of green-synthesized nanomaterials. NiF-NCs demonstrated improved electrochemical performance as compared to NiF-NPs. NiF-NCs exhibited a superior specific capacity (Q _s) of 136.8 C g^-1 at a current density of 1 A g^-1. Dunn's graph showed diffusive and capacitive-controlled current contributions. To analyze the practical applications of NiF-NCs, they were used against an activated carbon (AC) electrode in an asymmetric supercapacitor device, where they delivered a remarkable Q _s of 100.6 C g^-1 at 0.5 A g^-1. The determined value of specific energy (E _s) was 20.6 Wh kg^-1, and the specific power (P _s) was 835.9 W kg^-1. A coulombic efficiency of 99% and a capacitance retention 40% were recorded after running 10 000 GCD cycles. The excellent electrochemical properties and cycling stability reported in this work highlight NiF-NCs as an attractive and efficient nanomaterial for future energy storage technologies.