A high-performance pseudocapacitive electrode based on CuO–MnO2 composite in redox-mediated electrolyte

Abstract

In the present work, a simple and cost-effective precipitation approach was carried out to fabricate CuO nano-needle, and its electrochemical performance was evaluated in a redox-mediated electrolyte (2 M KOH and 0.3 M K3Fe(CN)6). A high specific capacitance of 2519 F/g was recorded at a specific current of 8 A/g. However, the electrode suffered from poor rate capability as the specific capacitance was rapidly decreased to 100 and 1 F/g when the specific current was increased to 30 and 50 A/g, respectively. The CuO nanoparticles were further modified with MnO2 by a hydrothermal method, and the resulting CuO–MnO2 (CMO6) electrode delivered a high specific capacitance of 539 F/g even at very high specific current of 50 A/g. The as-synthesized electrode materials were structurally and morphologically characterized using X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the CuO and MnO2–CuO composites have been examined in detail. Synopsis Modification of pristine CuO nano-needles with MnO2 nanosheets improved the electrochemical performance of the material. The composite was able to deliver a high specific capacitance of 539 F/g even at very high specific current of 50 A/g.