Fabrication of tunable band gap carbon based zinc nanocomposites for enhanced capacitive behaviour

Abstract

This manuscript highlights the tunable properties of carbon nanospheres by controlling the concentration of zinc nitrate in them. Zinc nitrate has converted the phase of carbon spheres, which has also altered the optical, structural and electrochemical properties of carbon nanospheres by forming nanocomposites. Carbon nanospheres and their nanocomposites have been synthesized by using a two-step hydrothermal method. X-ray diffraction analysis of the as synthesized material revealed the formation of carbon spheres and their nanocomposites. It is also observed that the crystallinity of the as synthesized material increases as the concentration of Zn(NO3)2.6H2O increases. UV- visible measurements revealed a blue shift in the as-synthesized samples. With the increase in the concentration of zinc, the band gap was also found to increase from 0.6 eV to 4.7 eV. The morphological and microstructural analysis of the as-synthesized samples showed the formation of nanospheres for as-synthesized carbon, and nano flakes for carbon nanocomposites. Fourier-Transform Infrared Spectroscopy (FTIR) measurement provided the information about the molecular structure and vibrational bands present in the samples. Electrochemical analysis of the thin film revealed the capacitive behaviour of the material. The aerial capacitance and Nyquist plot represents the capacitive properties of the material. The present study on carbon nanospheres and their nanocomposites showed that the material is a potential candidate for the application in capacitors, supercapacitors and energy storage devices.