Pseudocapacitive behaviors of strontium-doped cobalt ferrite nanoparticles for supercapacitor applications

Abstract

Metal oxides are widely used as electrode materials due to their high potential for various applications. Specifically, spinel-structured cobalt ferrite is employed in various energy applications. Among the available conventional techniques to synthesize nano-ferrites, the sol-gel combustion approach is one of the simplest and most effective. In this work, strontium-doped cobalt ferrite nanoparticles are synthesized using the sol-gel combustion technique and annealed at various temperatures. Further, the prepared samples are characterized using XRD to identify the phase and crystallinity of the materials. It shows the average crystallite sizes of 33, 36, and 35 nm for various temperatures of 200 °C, 300 °C, and 500 °C, respectively. FESEM illustrated the clustered and homogeneous structure of the sample. From UV-Vis-NIR absorption spectroscopy, direct bandgap energy values are calculated using Tauc’s plot as 1.24, 1.21, and 1.20 eV. To examine electrochemical properties, galvanostatic measurements are used. The observed sample (Co0.8Sr0.2Fe2O4 at 300 °C) shows a supercapacitance value of 637 Fg−1 at 0.5 Ag−1 and retained 85.5 % after 1000 cycles at 5 Ag−1, showing 98.79 % coulombic efficiency after 5000 cycles at 15 Ag−1. The result indicates that doped nanoferrites are a promising electrode material for supercapacitor applications.