Synergistic Enhancement of Charge Storage in Cr₂O₃–CuO Heterostructured Nanocomposites for High–Performance Supercapacitor Electrodes

The quest for electrode materials that simultaneously offer high specific capacitance, rapid charge-discharge kinetics, and prolonged operational stability continues to drive innovation in supercapacitor technology. This work presents a comprehensive electrochemical investigation of Cr₂O₃–CuO nanocomposites as advanced electrode materials for energy storage applications. The electrochemical performance of pristine Cr₂O₃ nanoparticles, CuO nanosheets, and their heterostructured nanocomposite was systematically evaluated through cyclic voltammetry, galvanostatic charge-discharge measurements, quantitative capacitance-diffusion contribution analysis, electrochemical impedance spectroscopy, and accelerated cycling tests. The Cr₂O₃–CuO nanocomposite exhibited remarkable specific capacitance values of 182.8 F g⁻¹ derived from cyclic voltammetry and 604.4 F g⁻¹ from galvanostatic charge-discharge analysis, substantially surpassing the performance of the individual oxide components. Quantitative analysis of the charge storage mechanism revealed a predominantly surface-controlled capacitive process contributing 90.9% to the total capacitance, indicating rapid kinetics favorable for high-power applications. The nanocomposite demonstrated exceptional electrochemical durability, retaining 87.5% of its initial capacitance after 2000 consecutive charge-discharge cycles. Electrochemical impedance spectroscopy confirmed significantly reduced charge-transfer resistance and enhanced ionic diffusion characteristics in the composite electrode. The superior electrochemical performance arises from the synergistic interplay between Cr₂O₃ nanoparticles and CuO nanosheets, which creates an interconnected network facilitating efficient electron transport, promotes electrolyte accessibility to electroactive sites, and provides abundant redox-active interfaces. These findings establish Cr₂O₃–CuO nanocomposites as highly promising electrode materials for next-generation supercapacitor devices requiring both high energy and power densities.