Triethanolamine–ethoxylate (TEA-EO) assisted hydrothermal synthesis of hierarchical β-MnO2 nanorods: effect of surface morphology on capacitive performance

Abstract

Abstract In this study we are presenting the synthesis of MnO2 nanorods using hydrothermal method assisted by facile tri-ethanolamine-ethoxylate. Structural (x-ray diffraction, Rietveld refinement), functional (Fourier Transform Infrared spectroscopy and x-ray Photoelectron Spectroscopy) and morphological (Field emission scanning electron microscope, Transmission electron microscopy) characterization conform the β-MnO2 nanostructure with a rod-like morphology and uniform thickness. The morphological variations of the nanorod thickness can be easily controlled by simply monitoring the reaction temperature. Comparative investigations of β-MnO2 samples synthesized at two different reaction temperatures (viz. 100 °C and 120 °C) used as a supercapacitive electrode material have been performed with the aid of different electrochemical techniques. With different electrolytes (Li2SO4 and Na2SO4), supercapacitor device is tested using Cyclic voltammetry, impedance spectroscopy and galvanostatic charge discharge. Interestingly, the low temperature synthesized β-MnO2 nanorods sample exhibit superior electrochemical performance in 1 mol l−1 Li2SO4 electrolyte in terms of high specific capacitance (462 Fg−1 at10 mVs−1), energy density (9.72 WhKg−1), and outstanding cyclic stability (90.26% over 2000 cycles).