Electrochemical properties of CoFe2O4 thin film electrodes prepared by spray pyrolysis

CoFe2O4 thin films have been prepared by chemical spray pyrolysis at various substrate temperatures and were characterized for structural, morphological, compositional, optical, electrical and electrochemical properties. X-ray diffraction studies confirmed the spinel cubic phase formation with crystallite size in the range of 15 to 23 nm. Field emission scanning electron microscopy images showed porous spherical granular like surface morphology. Optical bandgap was observed in the range of 2.33 eV to 2.54 eV with direct allowed type tran-sitions. The electrical resistivity measurement confirmed semiconducting behaviour. CoFe2O4 electrode prepared at 425 degrees C showed specific capacitance of 543 Fg- 1 at scan rate of 5 mVs- 1 from cyclic voltammetry and 575 Fg- 1 at current density of 0.5 Ag-1 from galvanostatic charge-discharge within potential window of 0 V to 0.55 V in aqueous 1 M KOH electrolyte. The specific energy and specific power of CoFe2O4 thin film prepared at 425 degrees C were found to be 17.86 Whkg-1 and 1108 Wkg-1 respectively at current density of 4 Ag-1. CoFe2O4 thin film prepared at 425 degrees C exhibited 93.03% retention of its specific capacitance after 1000 cycles at a current density of 1 Ag-1. Electrochemical impedance spectroscopy analysis confirmed the superior electrochemical properties of CoFe2O4 thin films. The good electrochemical performance suggests use of CoFe2O4 thin films for supercapacitors.

Automated summary

CoFe2O4 thin films were prepared using chemical spray pyrolysis and characterized for their structural, morphological, compositional, optical, electrical, and electrochemical properties. The films exhibited the spinel cubic phase with a crystallite size ranging from 15 to 23 nm. They showed a porous spherical granular surface morphology. The films had an optical bandgap of 2.33 eV to 2.54 eV and demonstrated semiconducting behavior. The CoFe2O4 thin film prepared at 425 degrees C showed excellent electrochemical properties, making it a potential candidate for supercapacitors.