Nickel-doped CuO/Cu/Cu2O nanocomposite as an efficient electrode for electrochemical non-enzymatic glucose sensor and asymmetric supercapacitor

Nickel-doped CuO/Cu/Cu2O nanocomposites were prepared by simple precipitation method. Nickel was doped at three different concentrations of 2 mM (Ni-Cu2O/CuO/Cu (NCO-1)), 4 mM (Ni-CuO/Cu/Cu2O (NCO-2)), and 6 mM (Ni-Cu2O/Cu (NCO-3) and was used as an electrode material for glucose sensing and energy storage applications. The X-ray diffraction spectroscopy (XRD) confirms the formation of different phases of CuO, Cu2O, and Cu in the NCO nanocomposites. Among the NCO samples, the NCO-2 nanocomposite showed two different surface morphologies of spherical-shaped nanoparticles with an average size of 35.97 nm and nanoflakes with an average length of 64.75 nm and a width of 25.21 nm. The X-ray photoelectron spectroscopy (XPS) analysis of NCO-2 confirms the presence of mixed oxidation states of Cu2+, Cu1+, Cu-0, and Ni2+. The electrochemical performance of NCO-2 nanocomposite is high compared to the other NCO composite which shows glucose detection sensitivity of 208.5 mu A mM(-1) cm(-2) and Limit of detection (LOD) of above 0.7 mu M for a linear range of 0.01 to 8 mM. Also, in supercapacitor application, the NCO-2 electrode material exhibits a high specific capacitance of 338.98 F g(-1) at the current density of 1 A g(-1) in 1-M KOH electrolyte compared to the other NCO composites. The aqueous asymmetric supercapacitor (ASC) device of cell configuration AC//Ni-doped CuO/Cu/Cu2O was fabricated which showed an energy density of 10.03 Wh kg(-1) and power density of 874.58 W kg(-1) at current density 1 A g(-1). The device showed excellent cyclic stability with a capacitance retention of 87.61% and good coulombic efficiency of 94.28% after 5000 cycles. [GRAPHICS] .