Chemically synthesized ZnFe2O4 electrodes for electrochemical oxygen evolution reaction and supercapacitor applications

The spinel ferrites are versatile group of metal oxides with good photoelectrochemical and unique magnetic properties, as well as low cost, biocompatible and huge abundance. The magnetic as well as photoelectrochemical properties have been extensively examined. Herein, we have synthesized zinc ferrite (ZnFe 2 O 4 ) thin films on nickel foam via spray pyrolysis method at substrate temperatures of 300, 400, and 500 °C. The physicochemical properties of ZnFe 2 O 4 films were investigated using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and fourier transform infrared spectroscopy (FT-IR) spectroscopy. Electrochemical properties oxygen evolution reaction and supercapacitive performance of ZnFe 2 O 4 thin films were investigated through linear sweep voltammetry, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The ZnFe 2 O 4 thin film synthesized at 400 °C exhibited an overpotential of 319 mV at a current density of 50 mA/cm 2 with a Tafel slope of 115 mV/dec. Furthermore, it also showed a specific capacitance of 335 F/g at 1 mA/cm 2 current density in 1 M KOH electrolyte.