Facile synthesis of CuO nanosheets as electrode for supercapacitor with long cyclic stability in novel methyl imidazole-based ionic liquid electrolyte

Hierarchical CuO nanosheets were synthesized through a facile, eco-friendly reflux deposition approach for supercapacitor electrode material for energy storage. The resultant CuO nanosheets were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption isotherm techniques. The supercapacitor behavior of CuO nanosheets was investigated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy in novel 0.1 M aqueous 1-(1'-methyl-2'-oxo-propyl)-3-dimethylimidazolium chloride [MOPMIM][Cl] ionic liquid as an electrolyte. The result demonstrate that CuO nanosheets exhibit specific capacitance of 180 F g(-1) at 10 mV s(-1) scan rate which is the highest value in ionic liquid electrolyte and 87% specific capacitance retention after 5000th cycle. The electrochemical performance proves CuO nanosheets as electrode with ionic liquid electrolyte for developing green chemistry approach in supercapacitor.