Binder‐Free Gr/CuO/Ni(OH) ₂ Hybrid Electrode for Enhanced Supercapacitor Performance via Two‐Step Electrochemical Synthesis

Hybrid energy storage systems that combine capacitive and faradaic materials offer a promising way to bridge the performance gap between batteries and supercapacitors. In this work, CuO/Ni(OH) ₂ nanocomposites were produced on graphite electrode using a two‐step electrochemical deposition process that did not require the use of binders. Structural and morphological characterisations using interferometric profilometry, scanning electron microscopy (SEM), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS) and X‐ray Diffraction (XRD) confirmed the successful formation of the hybrid architecture. Electrochemical tests in 4 M KOH revealed that the Gr/CuO/Ni(OH) ₂ electrode delivered a high areal specific capacitance of 488.2 mF cm ⁻² at 0.2 mA cm ⁻² , excellent stability over 6000 cycles with a capacitance retention of 88.75% and superior performance compared to single‐component electrodes. The hybrid device Gr/CuO/Ni(OH) ₂ //AC exhibited an energy density of 14.97 μWh cm ⁻² at a power density of 0.179 mW cm ⁻² . Two hybrid supercapacitors connected in series successfully illuminated a red and a yellow LED for several minutes. These results confirm the strong synergistic effect and high application potential of the Gr/CuO/Ni(OH) ₂ nanocomposite for advanced supercapacitor systems.