Enhanced alpha-Mn2O3 nanorods synthesized by one-pot hydrothermal route for supercapacitors

Abstract

Pseudo-capacitors are the emerging energy storage devices which forms a bridge between batteries and conventional capacitors. In the present work, alpha-Mn2O3 nanorods have been synthesized by one-pot acid-assisted hydrothermal method for supercapacitor applications. The alpha-Mn(2)O(3)nanorod electrode is characterized by X-ray diffraction, SAED, Transmission Electron Microscopy (TEM), EDX and tested for supercapacitor application. XRD results indicate polycrystalline nature of alpha-Mn2O3. TEM results reveal an optimum nanorod diameter of 7 nm and length of 100 nm with high aspect ratio of 1:4. The high aspect ratio obtained by acid assisted one-pot hydrothermal route and the possible growth mechanism are explored. The structural and morphological investigations reveal that the acid implementation and suitable reaction temperature plays a crucial factor in the formation of homogeneous alpha-Mn2O3 nanorods. The cyclic voltammetry redox kinetics indicates pseudo-capacitive behavior with an excellent specific capacitance of 1377 F g(-1) at 5 mVs(-1). The galvanostatic charge-discharge investigations reveal an excellent 69% capacitance retention even after 1000 cycles. Ex-situ SEM, XRD and impedance spectroscopy investigations have been carried out to understand the nature of alpha-Mn2O3 nanorod after 1000 cycles. The synergetic effect of nanorod architecture, nanoparticle presence has been discussed in terms of excellent supercapacitive behavior.