Enhanced supercapacitive performance of CuO/Cu2O/Cu nanostructures: a comparative study before and after plasma functionalization

CuO/Cu2O nanostructures were developed on copper substrates through an anodization process in a sodium hydroxide solution, with durations ranging from 0 to 900 s. This study examines how anodization improved the surface activity of the material, which was further enhanced by a two-hour (N2) plasma treatment. The influence of anodization time on the final layers’ structural, morphological and electrochemical properties was investigated. A cubic phase of CuO/Cu2O films was observed from X-ray diffraction (XRD) measurement. Surface roughness and nanostructure density were increased when anodization time was increased, this was confirmed by scanning electron microscopy (SEM). Further electrochemical performance was evaluated by cyclic voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and electrochemical Impedance spectroscopy (EIS). With an areal capacitance of 1250 mF.cm− 2, the sample that was anodized for 600 s and treated with (N2) plasma (Cu-600s-N2) showed the best supercapacitive behavior out of all the samples that were tested. The contributions of diffusion-controlled and capacitive mechanisms to the total amount of charge storage were examined using Dunn’s method. After plasma treatment, EIS measurements also revealed improved electronic conductivity and a sharp rise in electron lifetime from 64 ms to 1592 ms. These findings highlight the metal oxide nanostructures treated with (N2) plasma’s great potential for cutting-edge energy storage applications. The graphical abstract depicts the synthesis of CuO/Cu2O nanostructures through anodization followed by (N2) plasma treatment, highlighting the enhancement in surface morphology and supercapacitive performance, especially for the Cu-600s-N2 sample.