“…Nonetheless, to the best of our knowledge, there are only a limited number of studies on synthesis, characterization and electrochemical performance approach used for CuO nanoparticles in comparison to other metal oxides in the transition series such as ZnO [56], TiO 2 [57], SnO 2 [58], and Fe 2 O 3 [59], Mn 2 O 3 [38]. Some physical and chemical techniques have recently been described for synthesizing CuO nanoparticles, including sonochemical method [60], one-step solid-state reaction method at ambient temperature [61], electrochemical method [62], and sol-gel technique. The sol-gel process enables control over important structural factors like as morphology, particle size, crystallinity, and composition.…”