Fabrication and evaluation of hybrid supercapacitor consisting of nano cobalt oxide and manganese oxide deposited electrochemically on nanoporous Au-Electrode

This report describes the binder free super capacitance characteristics of cobalt and manganese oxides deposited by electrochemical deposition as layered and hybrid fashion on nanoporous Au current collectors, which is obtained by simple etching process by dipping 18 k gold foil in nitric acid as etchant. Structural and morphology of the materials are characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Field electron scanning electron microscope (FESEM). The specific capacitance values of the layered and hybrid electrodes are 1215 and 1334 Fg(-1) at the scan rate of 5 mVs(-1) respectively. The synergistic effect of the hybrid metal oxides displayed good volumetric capacitance (428 mFcm(-3)), which is 2 times greater than that of the layered electrode. Further, the hybrid electrode exhibits 82.3 degrees phase angle with lower time constant of 4 s in contrast to the layered electrode. The energy and power densities of layered and hybrid electrodes are found to be 24.37 Whkg(-1) at 450 Wkg(-1) and 48.1 Whkg(-1) at 460 Wkg(-1) respectively. Further, the practical use of the fabricated hybrid supercapacitor device is demonstrated. On charging three supercapacitor devices connected in series with 9.1 V dc power supply, the fabricated device illuminated a commercially available 2 V LED for 4.4 min. (C) 2019 Elsevier Ltd. All rights reserved.