Facile synthesis of well-ordered manganese oxide nanosheet arrays on carbon cloth for high-performance supercapacitors

Abstract

Well-ordered manganese oxide (MnO₂) nanosheet arrays (NSAs) were grown directly on carbon cloth via a simple in situ redox replacement reaction between potassium permanganate (KMnO₄) and carbon cloth without any other oxidant or reductant addition. The morphology of MnO₂ NSAs was examined by scanning and transmission electron microscopy and the phase structure of nanosheets (NSs) was analyzed by X-ray diffraction spectroscopy. Based on a series of time-dependent experiments, a possible growth process for this structure was proposed. The MnO₂ NSAs supported on carbon cloth were directly used as integrated electrodes for electrochemical capacitors. The ordered MnO₂ NSAs yielded high-capacitance performance with a high specific capacitance of 2.16 F cm⁻² at a charge and discharge current density of 5 mA cm⁻² and 1.01 F cm⁻² at 20 mA cm⁻² with a cycling ability (61.4% of the initial specific capacitance remains after 3000 cycles). The MnO₂ nanosheet arrays with large surface area and high degree of ordering, combined with the flexible carbon cloth substrate can offer great promise for large-scale supercapacitor applications.