Rare Earth metal oxide nanoparticle-infused polymer nanocomposites for enhanced supercapacitor electrodes

•Gd2O3/CP nanocomposite synthesized by oxidative polymerization with Gd2O3 (20 %).•SEM shows particle sizes: 300–500 nm for Gd2O3/PPy, 600–800 nm for Gd2O3/PIn.•GCD confirms pseudo-capacitance mechanism at Gd2O3/CP-CF-H2SO4 interface.•Specific capacitance: Gd2O3/PPy (341.61 F/g), Gd2O3/PIn (305.56 F/g) at 5 mV/s.•Interface capacitance: Gd2O3/PPy (13 mF, 23 mF), Gd2O3/PIn (14 mF, 8.7 mF). The contemporary energy shortage has spurred scientists to explore other options. In this regard, there's significant interest in utilizing electrochemical energy sources for converting and storing energy. Here, a fresh endeavor involves utilizing a set of semiconducting rare earth Gd2O3/conducting polymers (CP) (CP= polypyrrole, polyindole) for energy storage purposes. The synthesis method involves the straightforward oxidative polymerization of either indole or pyrrole to produce Gd2O3/PIn or Gd2O3/PPy, respectively. The integrity of the garnets synthesized was verified through XRD, Raman, XPS, FESEM, and TEM analysis, ensuring their phase purity and morphology. The scanning electron microscopy (SEM) analysis reveals the particle morphology, with sizes ranging from 100 to 800 nanometers. FTIR and Raman spectroscopy further validate the integration of Gd2O3 into the conducting polymer matrix. XRD shows broad peaks for amorphous structures in Gd2O3/PPy and Gd2O3/PIn nanocomposites. To evaluate its performance in supercapacitors, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and impedance spectroscopy (EIS) were employed using a three-electrode configuration. The rectangular CV curves indicate the pseudo-capacitance mechanism of the Gd2O3/CP nanocomposite-coated carbon fiber electrode in an H2SO4 electrolyte. Specific capacitance (SC) values for Gd2O3/PPy and Gd2O3/PIn binary nanocomposite electrodes are determined as 341.61 F/g and 305.56 F/g, respectively, from GCD curves. In hybrid energy systems, especially electric automobiles, the Gd2O3/PPy and Gd2O3/PIn nanocomposite-coated carbon fiber electrode has a potential of up to 1.8 V and short charging and discharging durations, implying fast-charging and extended lifespan. The easy oxidative polymerization process utilized to produce gadolinium oxide/conducting polymer nanocomposites for supercapacitors is the main breakthrough of this research.