Synthesis of MnO2/Carbon dots nanocomposite derived from rice Husk for supercapacitor electrodes

Abstract

This article reports the use of carbon dots (CDs) derived from rice husk that was composited with MnO2 to be applied as supercapacitor electrodes. CDs were synthesized by acid hydrolysis method with the addition of urea as nitrogen doping source. CDs produced were well dispersed in water and show a blue-green emission under UV light exposure. Photoluminescence test was carried out by excitation using a violet laser (405 nm) that showed a broad spectrum with the peak wavelength at 497 nm. The average particle size of CDs was found about 11 nm taken using particle size analyzer (PSA). MnO2/CDs nanocomposites were made by mixing MnO2 and CDs solution. X-ray Diffraction (XRD) analysis confirmed that the MnO2/CDs nanocomposites have been formed. Energy Dispersive X-ray Spectroscopy (EDXS) analysis confirmed the presence of any element that forming the nanocomposites. The electrodes were fabricated by coating the MnO2/CDs nanocomposites onto the glassy graphite electrode, then measured their electrochemical characteristics to determine the specific capacitance of the electrodes. The high specific capacitance value was found up to 300 F/g based on the cyclic voltammetry data.