Porous nano-MnO2: large scale synthesis via a facile quick-redox procedure and application in a supercapacitor

Abstract

A new type of porous nano-MnO₂ for supercapacitors has been synthesized for the first time by a facile sonochemistry route from a quick-redox reaction between KMnO₄ and D-glucose. The crystal structure, morphology and chemical composition of the MnO₂ product were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The results show that the porous MnO₂ nanoparticles in the range 20–50 nm are interestingly composed of nanorods with diameters of about 2 nm and lengths of 4–8 nm. A possible growth mechanism of this nanostructure has been identified based on the experimental results. The electrochemical properties of the porous MnO₂ were investigated in a symmetric capacitor cell using both 1 M Na₂SO₄ and 9 M KOH aqueous solutions. The results indicate that the MnO₂ electrodes have a good capacitive performance in both cases.