Preparation and capacitance behavior of manganese oxide hollow structures with different morphologies via template-engaged redox etching

Abstract

A variety of amorphous manganese oxide electrode materials with uniform nonspherical hollow interiors are prepared via sacrificial template-engaged redox etching of the corresponding shape-controlled Cu2O nanocrystals in KMnO4 aqueous solution at room temperature. The obtained materials are characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption. The amorphous manganese oxide hollow materials not only well inherit the size and shape of Cu2O nonspherical precursor, but also show a manganese average oxidation state of 3.7 and large specific surface area (about 198 m2 g−1). The electrochemical measurements show that the capacitance of the as-prepared amorphous manganese oxide electrode materials with uniform nonspherical hollow interiors is connects with their specific surface area. The amorphous manganese oxide star hollow architecture exhibits not only high specific capacitance of 366 F g−1 at a scan rate of 5 mV s−1, but also relatively good cycle stability (93.1% capacitance retention after 1000 cycles at a scan rate of 20 mV s−1), which make it have a potential application as a supercapacitor electrode material.