Characterization of CNTs and CNTs/MnO2 composite for supercapacitor application

Abstract

Manganese oxide (MnO2) was deposited on multiwalled carbon nanotubes (MWCNTs) via electrochemical deposition technique. Morphological and structural characterizations were examined using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Raman Spectroscopy. Cyclic voltammetry and Galvanostatic charge-discharge measurements were performed to study the electrochemical properties. 0.2 M Na2SO4 was used as an electrolyte for both experiments. For the purpose of the comparison, CNTs with different morphologies and water plasma treatment times were produced and optimized according to their capacitance performance. Results show that vertically aligned CNTs have improved capacitive performance than random aligned ones and that water plasma treatment cleans the amorphous carbon between nanotubes and increase the capacitance of CNTs from 0.19 to 1 mFcm-2. Finally, addition of 2-3 nm MnO2 layer on CNTs improve the capacitance significanltly from 1 to 4.5 mFcm-2 (465 Fg-1). Therefore, results demonstrate that MnO2/MWCNT composite is a promising material to use as an electrode in supercapacitors.