ABSTRACT The combustion synthesis approach has been used to successfully synthesize pure NiFe 2 O 4 and chromium‐doped NiFe 2 O 4 , that is, Ni (1− x ) Fe 2 O 4 :xCr 3+ (1 ≤ x ≤ 4 mol%), to enhance the electrochemical performance. Various techniques were employed to characterize the synthesized samples such as X‐Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), X‐Ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), and Energy dispersive X‐ray analysis (EDAX). The formation of the cubic phase was confirmed by matching the XRD patterns of the samples with ICSD card number 00–003‐0875. FESEM and EDAX analyses confirmed the presence of a porous surface morphology and precise elemental composition. The FTIR spectra exhibited an absorption peak at around 527 cm −1 , indicative of the tetrahedral FeO bond in NiFe 2 O 4 . The Ni2p core level spectra displayed from the XPS shift in binding energy as a result of Cr doping, which confirms the incorporation of Cr 3+ ions in NiFe 2 O 4 . The electrochemical properties of the fabricated electrode were investigated using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) which confirmed the superior performance of the 3 mol% Cr‐doped NiFe 2 O 4 (N4) electrode. It delivered a specific capacitance of 745.6 F g −1 at a current density of 4 A g −1 , with a bulk resistance ( R b ) of 1.37 Ω. After 4000 cycles at 20 A g −1 , the electrode retained 79.86% of its initial capacitance and maintained 60.48% of its specific capacitance at higher current densities. These findings underscore the effectiveness of Cr 3+ doping in improving the electrochemical characteristics of NiFe 2 O 4 nanoparticles, establishing them to be potential candidates for high‐performance supercapacitor applications.
Sharma et al. (2026) studied this question.