Optimizing La2MnXO6 Double Perovskite for Superior Electrochemical Efficiency in Supercapacitors

Double perovskite oxides (POs) are effective electrode materials for supercapacitors (SCs). Nevertheless, adapting their unique architectures to boost the electrochemical performance remains tricky. Herein, we present exceptional La2MnXO6 (X = Co, Fe) double perovskites as SC electrode materials. The sol-gel method has prepared La2MnCoO6 (LMCO) and La2MnFeO6 (LMFO) nanorods. XRD revealed that LMCO and LMFO have monoclinic crystal structures with lattice constants of a = 5.517 & Aring;, b = 5.528 & Aring;, c = 7.805 & Aring;, beta = 89.926 degrees, and a = 5.549 & Aring;, b = 5.557 & Aring;, c = 7.783 & Aring;, beta = 89.931 degrees, respectively. Scanning electron microscopy indicated the existence of uniformly distributed nanorods. The bandgap using Tauc's plot was determined as 1.38 and 1.24 eV for La2MnCoO6 and La2MnFeO6, respectively. Fourier-transform infrared spectroscopy further characterized the prepared LMCO and LMFO nanorods. X-ray photoelectron spectroscopy investigation confirmed the existence of La3+, Mn3+, Fe3+, O2-, and La3+, Mn3+, Co3+, O2- ions on the surface of La2MnFeO6 and La2MnFeO6, respectively. The specific capacitance achieved was 333.86 and 880.5 F/g @ 2.5 A/g for La2MnCoO6 and La2MnFeO6, respectively, using 1 M KOH electrolyte. La2MnFeO6 demonstrated excellent energy and power density of 30.5 Wh/kg and 625 W/kg. The asymmetric CV curve shape proved that we have battery-type SC behavior due to the indication of redox reactions. Furthermore, Dunn's technique evaluated the percentage contribution of capacitive and diffusion behavior. Our strategy using LMCO and LMFO nanorods material improved specific capacitance activity and significantly offered a facile guideline for targeting double perovskite electrodes for SC applications.