Green synthesis of ZnO nanoparticles from Neem and Eucalyptus leaves extract for photocatalytic applications

Abstract

Green synthesis of Zinc oxide (ZnO) nanoparticles (NPs) from leaf extracts involves simple, stable, cost-effective, eco-friendly, economically viable, sustainable and feasible approach. This method is more beneficial than conventional methods like physical and chemical methods, as they are toxic, expensive, non-biocompatible and causes environmental contamination. The present work focuses on Neem, and Eucalyptus leaves mediated synthesis of ZnO NPs and its photocatalytic capability towards the degradation of methylene blue (MB) dye. Here, the phytochemicals present in the leaf extract play a binary role by acting as effective capping and reducing agents in the synthesis process. In this work, we have synthesized three samples of ZnO NPs; one is using Neem leaf extract (ZnO-Nee.), second one is using Eucalyptus leaf extract (ZnO-Euc.) and the third one is using both the leaves extract together (ZnO-N&E). The structural, morphological and optical properties were analysed using X-ray diffraction (XRD), UV–Vis, Raman, fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM) techniques. The structural data confirmed single hexagonal phase wurtzite crystalline structure for all the three samples. The absorption spectra showed variation in the band gap of three NPs, evaluated using Tauc method. Mixed morphology of polygon, rod and sphere is observed for all the NPs. The photocatalytic degradation of MB pollutant using ZnO photocatalyst followed green protocol and achieved an excellent result with slight variation in the photocatalytic efficiency percentage. The highest photocatalytic decomposition of MB pollutant is observed for ZnO-Nee. sample as 97.98%. This photocatalytic study can make the synthesised ZnO NP as an efficient agent for water pollution by varying physicochemical parameters.