Preparation and characterization of NiFe₂O₄ thin films for supercapacitor applications

ABSTRACT

Mesoporous NiFe₂O₄ thin films have been prepared by chemical spray pyrolysis. The films are characterized by XRD, FESEM, EDAX, UV-Visible spectroscopy, DC electrical resistivity and electrochemical measurements. XRD result shows the cubic crystal structure with Fd-3 m (227) space group. Crystallite size is found in the range of 14–21 nm. FESEM showed crack free, well defined, uniform, mesoporous spherical grain-like surface morphology. EDAX study confirmed nearly stoichiometric deposition. The optical absorption studies confirmed direct allowed type transition with bandgap in the range of 2.09–2.29 eV. The films showed room temperature electrical resistivity of 2.34 × 10⁴ Ωcm. The NiFe₂O₄ thin film spray deposited at 450°C exhibited a specific capacitance of 591 Fg⁻¹ at a scan rate of 5 mV·s⁻¹ from CV and specific capacitance of 632 Fg⁻¹ at a current density of 0.5 Ag⁻¹ from GCD. These findings recommend a constructive route towards the preparation of NiFe₂O₄ electrodes for high-performance electrochemical supercapacitors.

KEYWORDS:

• Spray pyrolysis
• NiFe₂O₄
• supercapacitor
• electrochemical impedance spectroscopy

Disclosure statement

No potential conflict of interest was reported by the author(s).