Effect of synthesis route on the electrochemical performance of CoMnFeO4 nanoparticles as a novel supercapacitor electrode material

Abstract

In this study, CoMnFeO4 ternary metal oxide nanoparticles are prepared via hydrothermal and sol-gel ignition methods. Their structures are investigated and characterized by FT-IR, XRD, XPS, BET, SEM, EDX and HR-TEM analysis. Also, magnetic properties of nanoparticles synthesized by two methods are compared on a vibrant sample magnetometer (VSM) with maximum saturation magnetization values found to be 28.83 emu g−1 and 23.17 emu g−1, respectively. SEM and HR-TEM results reveal that the mean particles size of hydrothermally synthesized (about 25 nm) nanoparticles is smaller and more uniform than that of their counterparts synthesized by sol-gel ignition method (about 65 nm). Their supercapacitor behaviors are studied and compared by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) methods. The hydrothermally synthesized sample shows higher specific capacitance of about 770 F g−1 (at 1 A g−1) in 3 M KOH while this value for the sample synthesized by sol-gel ignition approach is about 150 F g−1. The higher specific capacitance can be attributed to smaller particle size, more electroactive sites due to higher specific surface area, and quantum size effects. Also, some initial mechanistic studies are performed to achieve a deeper insight into the electrochemical behavior of the nanoparticles implying that the oxidation-reduction process of nanoparticles is generally quasi-reversible and diffusion-controlled. So, by considering the higher performance, the hydrothermal approach developed here is beneficial from cost, time and environmental points of view.