Comparative study of electrochemical performance of 3D leaf-like MnO2 and Mn2O3 powder for supercapacitor application

In the present work, we report the difference between the electrochemical behavior of MnO2 and Mn2O3, which are synthesized in the presence and absence of Ni foam, respectively, using simple and facile hydrothermal method. The X-ray diffraction (XRD) patterns of MnO2 and Mn2O3 samples revealed the presence of orthorhombic and cubic phases, with the p n n m and Ia3¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline{3 }$$\end{document} space groups, respectively. The FE-SEM showed the 3D leaf-like structure of MnO2 over the Ni foam and the agglomeration of the powder of the Mn2O3 sample. The molecular fingerprint and chemical composition of the MnO2 and Mn2O3 has been confirmed from the Raman spectra and FTIR, respectively. The presence of Mn4+ and Mn3+ oxidation states in MnO2 and Mn2O3, respectively, was verified by XPS results. The electrochemical performances indicate the maximum specific capacitance of MnO2 and Mn2O3, 212 and 338 F/g, at the scan rate of 5 mV/s. Basic Mn2O3 is also showing better capacity retention than MnO2 after 500 cycles in 3 M KOH electrolyte.