Structure, cation valence states and electrochemical properties of nanostructured Mn3O4

Nanostructured Mn3O4 with an average crystallite of 10 nm is synthesized by the controlled reduction of potassium permanganate using hydrazine. The phase purity, average crystallite/particle size, morphology and state of agglomeration were studied using X-ray diffraction (XRD), Transmission Electron microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses. Nitrogen sorption studies give a specific surface area of 62 m(2)/g and also reveal the mesoporous nature. The presence of Mn4+ ions is inferred from the Fourier Transform Infra-Red (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS) studies. The decrease in the c/a ratio obtained from XRD analysis also indicates the presence of Mn4+ ions. Electrochemical analysis was done on a symmetric capacitor with nanostructured Mn3O4 as the active material and 6 M KOH solution as the electrolyte. Cyclic voltammograms revealed pseudocapcitive behavior with specific capacitance values falling sharply with scan rate. The power density and energy density values obtained from chornopotentiograms are fairly large and indicate the potential application in the field of supercapacitors. (C) 2015 Elsevier Ltd. All rights reserved.