Tea-phytochemicals functionalized Ag modified ZnO nanocomposites for visible light driven photocatalytic removal of organic water pollutants

Abstract

Biogenic synthesis of semiconductor nanoparticles (NPs) as well as metal-semiconductor nanocomposites (NCs) has become a subject of comprehensive interest and research due to its cost-effective and eco-friendly synthesis approach. In this regard, the current work focuses on the biosynthesis of Zinc oxide (ZnO) NPs and Silver-Zinc oxide (Ag-ZnO) NCs using the leaves extract of tea plant (Camellia sinensis). The as-synthesized samples were characterized by various optical, structural and elemental characterization techniques. The successful capping of tea-phytochemicals were confirmed from the bonding information through Fourier Transform Infrared Spectroscopic analysis, while the formation of ZnO NPs and Ag-ZnO NCs were established using x-ray Diffraction, Energy Dispersive x-ray and x-ray photoelectron spectroscopic techniques. Optical absorbance of ZnO NPs revealed the formation of smaller particle size (∼5.2 nm) as compared to bulk ZnO, while the absorbance of Ag-ZnO NCs depicted the presence of metallic Ag in the sample through surface plasmon resonance. The potential of as-synthesized samples were then tested through the photocatalytic and catalytic degradation of organic water pollutants, such as Methylene blue, Paracetamol drug and para-Nitro phenol. The results indicated that Ag deposition on ZnO nanostructure was beneficial in terms of both catalytic as well as photocatalytic degradation under dark condition and visible light irradiation, respectively. A commercially available light source was used for photodegradation process instead of solar irradiation. In addition, an attempt has also been made to explain the plausible pathway of Ag-ZnO NCs formation by the functionalization of tea-phytochemicals. To the best of Authors’ understanding, this is the first attempt so-far reporting a cost-effective biosynthesis process of Ag-ZnO NCs using tea-extracts and its photocatalytic activity under visible light for the degradation of common organic pollutants.