Electrochemical performance of NiFe2O4 nanostructures incorporating activated carbon as an efficient electrode material

The quest for cost-efficient electro-active materials exhibiting high specific capacitance is currently a key focus in energy-related research. Owing to their high capacitance values, metal oxides (MOs) are preferably being utilized for energy storage applications as electrode materials in supercapacitors. However, the electrochemical performance of MOs is hindered due to less specific surface area and high tendency towards aggregation. Therefore, tuning in electrochemical activity of MOs is essential. In this framework, NiFe₂O₄ was prepared using a facile and cost-effective citrate-gel followed by auto-ignition method, and was incorporated with activated carbon contents to tune the electrochemical performance. Formation of inverse spinel structure of NFO and its stability throughout the compositions was examined using X-ray diffraction analysis. Well-dispersed, spherical and porous morphological features were visualized using a field emission scanning electron microscope. The electrochemical analysis was conducted using CH instruments 660 E via freshly prepared 4 M KOH solution. Cyclic voltammetry was carried out at constant potential window of 0.25–0.65 V and different scan rates (0.009–0.08 Vs^-1). The pseudo-capacitive behavior was perceived from occurrences of oxidation/reduction peaks. In addition, charge/discharge curves revealed cyclic stability over long range cycles. Specific capacitance, discharge time, energy and power density values were also measured for all the compositions and NFO with 1% activated carbon was found to be the most suitable candidate for use as electrode materials in the present work.