Unleashing the potential of Vitex negundo leaves: innovative fabrication of Cu-Ag-ZnO nanocomposite for enhanced photocatalytic degradation of caffeine and Congo red dye coupled with antimicrobial efficacy

Abstract

In this work, we reported here the design and facile fabrication of copper, silver-co-doped zinc oxide nanocomposite (Cu-Ag-ZnO NC) using leaves extract for their application in photocatalytic degradation of emerging pollutants, i.e., Caffeine and Congo red dye. Anthropogenic contaminants, specifically caffeine and Congo red dye, are frequently detected in aquatic environments. Caffeine is most commonly used in personal care products and important pharmaceuticals, while Congo red is a common dye used for coloring fabric in the textile industry. These toxic compounds came out in freshwater as effluent from industrial and academic institutions. These contaminants into water bodies, posing a significant risk to both flora and fauna. To address this environmental challenge, our study focuses on developing eco-friendly NC via green methodology using plant-based extract as stabilizing and capping agent. Herein, utilizing Vitex negundo leave extract, we successfully isolated Cu-Ag-ZnO NCs under ambient reaction conditions. The isolated material was thoroughly characterized using various advanced analytical techniques prior to their evaluation as an effective photocatalyst and antimicrobial agent. X-ray diffraction (XRD) analysis revealed distinct crystalline peaks characteristic of ZnO within the NC besides the presence of copper and silver as dopants. The crystallite size of the Cu-Ag-ZnO NCs was determined to be 35.23 nm. Furthermore, scanning electron microscopy (SEM) clearly illustrated the spherical morphology of NC with an average particle size of 21.851 nm. This trimetallic co-doped material exhibited excellent antimicrobial (Gram-positive and Gram-negative) and antifungal activities, determined by minimum inhibitory concentration (MIC) method. Cu-Ag-ZnO NC exhibited strong antibacterial action against Gram-positive bacterial strains, i.e., S. aureus and E. coli having MIC value of 0.488 µg/mL in comparison to 3.78 µg/mL of standard, i.e., Chloramphenicol. The green synthesized Cu-Ag-ZnO NC also exhibited an amazing antifungal activity against A. niger having a MIC value of 0.976 µg/mL in comparison to 15.625 µg/mL of the standard drug, i.e., Nystatin. Furthermore, Cu-Ag-ZnO NC exhibited impressive photocatalytic activity under UV irradiation, achieving over 95% and 88% degradation of caffeine and Congo red respectively within 25 min. The noted reusability of NC is up to seven and six times for caffeine and Congo red degradation, respectively. In a nutshell, it is delineated that more frustrated materials due to entropic enhancement and band gap alteration are potential active materials toward catalysis as well as biological applications. The study delves into their efficiency, durability, and environmental sustainability, positioning such NCs as promising candidates for eco-friendly solutions in various fields.

Graphical abstract