Comparative study of electrochemical performance of 3D leaf-like MnO 2 and Mn 2 O 3 powder for supercapacitor application

In the present work, we report the difference between the electrochemical behavior of MnO 2 and Mn 2 O 3 , 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 MnO 2 and Mn 2 O 3 samples revealed the presence of orthorhombic and cubic phases, with the p n n m and Ia 3 space groups, respectively. The FE-SEM showed the 3D leaf-like structure of MnO 2 over the Ni foam and the agglomeration of the powder of the Mn 2 O 3 sample. The molecular fingerprint and chemical composition of the MnO 2 and Mn 2 O 3 has been confirmed from the Raman spectra and FTIR, respectively. The presence of Mn 4+ and Mn 3+ oxidation states in MnO 2 and Mn 2 O 3 , respectively, was verified by XPS results. The electrochemical performances indicate the maximum specific capacitance of MnO 2 and Mn 2 O 3 , 212 and 338 F/g, at the scan rate of 5 mV/s. Basic Mn 2 O 3 is also showing better capacity retention than MnO 2 after 500 cycles in 3 M KOH electrolyte.