Coral‐Structured CuO/Cu 2 O on Copper Foil as a Binder‐Free Electrode for Dopamine Sensing and Supercapacitor Applications

Abstract The present investigation utilizes a chemical oxidation technique to generate CuO/Cu 2 O coral structures on Cu foils, designed for application as electrodes in sensing and supercapacitor applications. The Cu(OH) 2 nanobelts obtained upon chemical oxidation are further oxidized at 500 °C in an Ar atmosphere, dehydrating into a mixed oxide of CuO/Cu 2 O. As the annealing temperature increases, the belt‐like morphology transforms into coral‐like structures, improving electrode performance. Structural and compositional characteristics are investigated using X‐ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and energy dispersive X‐ray spectroscopy. Electrochemical behavior is studied through cyclic voltammetry, galvanostatic charge‐discharge, linear sweep voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The CuO/Cu 2 O electrodes sintered at 500 °C function as sensors capable of detecting low levels of dopamine, with a limit of detection of 0.507 µM and a sensitivity of 1.03 µA/µM.cm 2 . Simultaneously, the electrodes exhibit an areal capacitance of 1104 mF/cm 2 at a current density of 1 mA/cm 2 and show excellent cyclic stability, retaining 92% of their initial capacitance after 5000 cycles. Notably, the CuO/Cu 2 O electrodes developed on Cu foil demonstrate excellent mechanical flexibility, making them ideal for flexible, binder‐free energy storage and sensing devices.