Preparation and electrochemical capacitance of MnO2 thin films doped by CuBi2O4

Manganese dioxide (MnO2) and CuBi2O4-doped MnO2 thin films with different nanostructures were deposited on indium tin oxide (ITO) glass and Ti foil substrates by using a chemical bath deposition (CBD) technique. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron microscopy (XPS). The effects of doping and substrates on electrochemical properties of MnO2 and CuBi2O4-doped MnO2 thin films on ITO glass and Ti foil were investigated. Capacitive properties of MnO2 and CuBi2O4-doped MnO2 thin films electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 0.1 M Na2SO4 aqueous solution as electrolyte. Specific capacitance, obtained from electrochemical measurement for the CuBi2O4-doped MnO2, exhibited a higher value of 338 F g−1 compared to the MnO2 exhibiting value of 135 F g−1. In addition, CuBi2O4-doped MnO2 thin films on an ITO electrode had a better and satisfactory specific capacitance value, and exhibited more excellent electrochemical stability and reversibility than Ti foil substrates.