A new CuO/TiO2 nanocomposite: An emerging and high energy efficient electrode material for aqueous asymmetric supercapacitors

The key to energy conversion and storage for supercapacitors is the development of easy-to-prepare electrode materials with high capacity performance. We have synthesized a series of nanocomposites based on copper oxide (CuO) and titanium dioxide (TiO2), symbolized as CuO/TiO2 with varying wt% Firstly, the current research uses a low-cost wet chemical method for high-performance asymmetric supercapacitor (ASC) ratios of CuO. Nanocomposites formation and morphological evaluations were confirmed via a series of characterization techniques, e.g., SEM, XRD, Raman, and XPS certified the highly crystalline nature and purity of the samples. The electrochemical properties were tested using the conventional three and two-electrode system that exhibited an excellent energy storage performance even at a low current of 1 A g−1. The TiO2-30 % CuO electrode had a greater specific capacitance of 553 F g−1 than pure CuO (226 F g−1) and TiO2 (115 F g−1) at the constant discharge current density of 1 A g−1. Moreover, an ASC was assembled by utilizing a TiO2-30 % CuO electrode and activated carbon (AC) as positive and negative electrodes respectively. The TiO2-30 % CuO//AC ASC delivered a high energy density of 34 Wh kg−1 at 800 W kg−1 and retained 18 Wh kg−1 when the specific power increased to 4800 W kg−1 at 1 A g−1. Our ASC exhibited excellent stability of 96 % retention after 10,000 cycles with superb rate capability at a wide voltage frame of 1.6 V. According to density functional theory calculations, CuO/TiO2 improved the material's electrical conductivity and electrochemical performance. The data suggested that the CuO/TiO2 nanocomposites, with optimum concentration of CuO, could be used as a good supercapacitor electrode material in the future.