NiFe2O4 nanoparticles as highly efficient catalyst for oxygen reduction reaction and energy storage in supercapacitor.

Nickel ferrite (NiFe 2 O 4) nanostructures (NSs) were synthesized via a low-cost and reproducible co-precipitation method. The as-synthesized material was annealed at different temperatures to investigate electrochemical performances for oxygen reduction reaction (ORR) and energy storage capacity. The X-ray diffraction (XRD) pattern confirmed the cubic structure of NiFe 2 O 4 (NF) NSs. The decreased agglomeration and increased particle size were observed by field effect scanning electron microscopy (FE-SEM) with annealing temperature. The presence of Ni–O and Fe–O bonds at tetrahedral and octahedral sites was confirmed by Fourier transform infrared (FTIR) spectroscopy. The electrochemical analysis studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) demonstrated that the NF NSs annealed at 900 °C exhibited impressive electrochemical activity with a specific capacitance of ∼136 F/g, outperforming samples synthesized at lower temperatures. Moreover, the electrode material displayed excellent long-term stability over 3000 cycles for ORR activity. The remarkable electrochemical performance of NF NSs at higher annealing temperatures highlights their potential for future energy storage and conversion devices. [Display omitted] • The NiFe 2 O 4 NPs were successfully synthesized by using a simple and economical co-precipitation method. • The cubic nature of the NF NPs was confirmed by XRD and HR-TEM analysis. • The NF annealed at 900 °C showing the highest capacitance of 136 F/g. • The NF NPs having excellent long-term stability over 3000 cycles. [ABSTRACT FROM AUTHOR]