Synthesis and characterization of zinc oxide nanoparticles and activated charcoal based nanocomposite for supercapacitor electrode application

Abstract

In this study, zinc oxide (ZnO) nanoparticles (NPs) have been synthesized at room temperature by co-precipitation method. It has been used as an electrode material by making composite with activated charcoal (AC) powder for its application in energy storage devices such as a supercapacitor. For synthesis of ZnO nanoparticles, zinc nitrate hexahydrate {Zn(NO3)2} and sodium hydroxide (NaOH) have been used as an initial precursor. The ZnO nanopowder obtained by using co-precipitation has been calcined at 400, 500, and 600 °C for 2 h. The nanoparticles have been characterized using Synchrotron radiation based angle dispersive X-ray diffraction (ADXRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Supercapacitor cells have been fabricated by using of zinc oxide nanoparticles-activated carbon (AC) nanocomposite electrode in different composition (weight ratios) from 1:1 to 1:2. Electrochemical properties of the prepared nanocomposite electrodes and fabricated supercapacitor cells have been characterized using a.c. impedance, cyclic voltammetry (CV) and charge discharge (CD) techniques by using 6 M KOH and 1 M NaOH as an electrolyte. The ZnO–activated carbon nanocomposite electrode with 6 M KOH showed a maximum capacitance of 479.6 mF cm−2, which is equivalent to single electrode specific capacitance of 342.6 F g−1. Similarly, the ZnO–activated carbon nanocomposite electrode with 1 M NaOH showed a maximum capacitance of 456.5 mF cm−2, which is equivalent to single electrode specific capacitance of 326.1 F g−1. The electrochemical behavior of the neat ZnO nanoparticles has also been studied. The specific capacitance of the supercapacitor is stable up to 2000 cycles at 100 mV cm−2, which shows that the device has good life cycle and electrochemical reversibility with 6 M KOH and 1 M NaOH electrolyte.