Triethanolamine–ethoxylate (TEA-EO) assisted hydrothermal synthesis of hierarchical β-MnO<sub>2</sub> nanorods: effect of surface morphology on capacitive performance
Yogesh Kumar, Santosh J. Uke, Ashwani Kumar, S P Merdikar, Meenal Gupta, Awalendra K. Thakur, Patrizia Bocchetta, Anshu Gupta, Vinay Kumar, Yogesh Kumar
Abstract
Abstract In this study we are presenting the synthesis of MnO 2 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 -MnO 2 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 -MnO 2 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 (Li 2 SO 4 and Na 2 SO 4 ), supercapacitor device is tested using Cyclic voltammetry, impedance spectroscopy and galvanostatic charge discharge. Interestingly, the low temperature synthesized β -MnO 2 nanorods sample exhibit superior electrochemical performance in 1 mol l −1 Li 2 SO 4 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).