Study of Structure and Electrochemical Properties of LaFeO₃ and La₂FeO₄ as Electrode Materials for Super-Capacitor Application ^†

Perovskite oxides have introduced a new advancement in the field of energy storage technologies, because of their outstanding properties. Perovskite oxides are a diverse and exciting class of compounds that have attracted a lot of interest. Perovskite oxides have attracted considerable interest as potential electrode materials for supercapacitors due to their unique structure, compositional flexibility, and intrinsic oxygen vacancy. Synthesized single-phase perovskite LaFeO₃ and its 2D equivalent Ruddlesden-Popper oxide La₂FeO₄ were obtained via a solid-state reaction method. X-ray diffraction and field emission scanning electron microscopy techniques have been used to study the crystal structure and surface morphology of the produced materials, respectively. The optical band gap for LaFeO₃ is 2.10 eV, while for La₂FeO₄, it is 2.04 eV, as determined by UV-vis measurements. Electrochemical impedance spectroscopy (EIS), charge/discharge analysis, and cyclic voltammetry have been used to study the electrochemical characteristics. Both of the samples exhibited typical pseudocapacitor behavior, as indicated by the presence of a redox peak in cyclic voltammetry, which was recorded in the potential window of 0 to −1 V. For both the compounds, the faradic charge transfer resistance (R_ct) was determined to be ~1 Ω. After 100 cycles of the charge/discharge testing, the specific capacitance in a 3M KOH electrolyte solution is found to be 6 Fg-1 and 10 Fg-1, respectively for LaFeO₃ and La₂FeO₄.