Green synthesis of ZnO and CuO NPs using Ficus benghalensis leaf extract and their comparative study for electrode materials for high performance supercapacitor application

In this paper, we present green synthesis of zinc oxide (ZnO) nanoparticle (NPs) and copper oxide (CuO) NPs using leaf extract of Ficus benghalensis (banyan tree) and their study for high performance supercapacitor application. Herein, we have used 1 mL freshly prepared leaf extract of Ficus benghalensis as capping/stabilizing agent for the synthesis of ZnO and CuO NPs. These synthesized NPs have been characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), powder X-ray diffraction (PXRD) and fourier transform infrared spectroscopy (FTIR). The SEM images of ZnO and CuO NPs show morphology of both the nanoparticles. The EDS, FT-IR and XRD data are used for the structural characterization of nanoparticles. The presence of phytochemicals (organic compounds) at the surface of nanoparticles confirms their capping/stabilizing role in the synthesis of the nanoparticles. The cyclic voltammetry (CV) study has been done for getting specific capacitance (Cs) for supercapacitor application. The obtained values of specific capacitance (Cs) for ZnO NPs are 6.318 F g(-1) at 20 mV/s, 4.363 F g(-1) at 40 mV/s , 3.611 F g(-1) at 60 mV/s, 3.222 F g(-1) at 80 mV/s and 2.972 F g(-1) at 100 mV/s respectively. In the same manner, the obtained values of specific capacitance for CuO NPs are 2.144 F g(-1) at 20 mV/s, 1.916 F g(-1) at 40 mV/s, 1.846 F g(-1) at 60 mV/s, 1.775 F g(-1) at 80 mV/s and 1.725 F g(-1) at 100 mV/s respectively. The values of energy density have been calculated for both ZnO NPs and CuO NPs. The calculated values of energy density for ZnO NPs at the abovementioned scan rates are 1.0620 Wh/kg, 0.7334 Wh/kg, 0.6070 Wh/kg, 0.5416 Wh/kg and 0.4996 Wh/kg respectively. Similarly, the calculated values of energy density for CuO NPs are found to be.0.1904 Wh/kg, 0.1701 Wh/kg, 0.1639 Wh/kg, 0.1576 Wh/kg, and 0.1532 Wh/kg respectively. (C) 2021 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Global Conference on Recent Advances in Sustainable Materials 2021.