Effect of precipitating agent $\mathrm{NaOH}$ on the preparation of copper oxide nanostructures for electrochemical applications

Copper oxide ($\mathrm{CuO}$) nanostructures with different concentrations of sodium hydroxide for electrochemical applications such as supercapacitors have been synthesized using a simple and low-cost precipitation method. X-ray diffraction pattern confirmed the formation of $\mathrm{CuO}$ nanostructures without any impurities and further confirmed its highly crystalline, single phase, monoclinic nature. UV-diffuse reflectance spectral (UVDRS) studies provided the absorption edge of the material and the estimated band gap value for the nanostructures were calculated using Kubelka–Munk (KM) absorbance plot that are determined to be around $4.74$ – $4.84$ eV. Field emission scanning electron microscopy (FESEM) investigations revealed the morphology of the copper oxide nanocrystals and showed the increment of diameter of the $\mathrm{CuO}$ nanostructures. The electrochemical behavior of the $\mathrm{CuO}$ nanostructures were investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques which showed the stability, reversibility, symmetric and capacitive nature of the nanostructures.