CuO–PAA hybrid films: Chemical synthesis and supercapacitor behavior

We report the synthesis of CuO–Poly (acrylic) acid (PAA) hybrid thin films by a cost-effective spin coating technique for supercapacitor application. Coated films were annealed at 300, 400 and 500 °C, to study the annealing effect on the supercapacitor behavior. Further films were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform-Raman spectroscopy (FT-Raman) and Fourier transform-Infrared spectroscopy (FT-IR) techniques. Energy dispersive spectroscopy (EDS) shows the formation of amorphous blend of CuO and Cu2O phases at 300 °C. Further, films annealed at 400 and 500 °C exhibit polycrystalline phase pure CuO with monoclinic structure. The scanning electron microscopy (SEM) micrographs show the transition of island-like structure to CuO crystals surrounded by PAA grafted composite ring with increase in annealing temperature. The possible growth mechanism of PAA and CuO bonding is discussed. Cyclic voltammetry (CV) is employed to calculate the specific capacitance (Csp) in 1 M H2SO4 electrolyte. It is observed that the Csp increases from 41 to136 F g−1 with increase in annealing temperature.