A facile one-pot synthesis of highly efficient ZnO nanoparticles with enhanced photocatalytic and antibacterial performance

An eco-friendly approach was employed to synthesize ZnO, Y@ZnO (yttrium-doped ZnO), AC@ZnO (Activated Charcoal-doped ZnO), and Y@AC@ZnO (yttrium and Activated Charcoal-co-doped ZnO) nanoparticles (NPs) using Hybanthus enneaspermus leaf extract. Comprehensive characterization of these synthesized materials using various analytical techniques confirmed their wurtzite structure. The crystallite sizes for ZnO, Y@ZnO, AC@ZnO, and Y@AC@ZnO NPs were found to be 37, 38, 40, and 42 nm, respectively. UV–visible spectroscopy revealed absorbance peaks between 335 and 355 nm, correlating to energy band gaps of 3.76, 3.70, 3.68, and 3.65 eV. Photoluminescence (PL) spectra exhibited notable blue, green, and red emissions upon excitation at 410, 493, and 522 nm for ZnO, Y@ZnO, AC@ZnO, and Y@AC@ZnO NPs, respectively. Morphological analysis indicated high porosity in the NPs, with dopants influencing the size and shape of the nanoparticles. These materials were tested as photocatalysts for the decomposition of methylene blue (MB) under UV light, showing that decomposition efficiency was significantly dependent on UV exposure duration. The highest decomposition efficiency of 85.3% was achieved using Y@AC@ZnO. The photocatalytic decomposition followed a first-order reaction, with reaction rate constants for MB decomposition in the presence of ZnO, Y@ZnO, AC@ZnO, and Y@AC@ZnO NPs being 0.0523, 0.0736, 0.969, and 0.1145 min^-1, respectively. The synthesized ZnO nanoparticles were tested for antibacterial activity against Vibrio, Pseudomonas, and E. coli using the agar disk diffusion method. ZnO, Y@ZnO, AC@ZnO, and Y@AC@ZnO NPs exhibited superior antibacterial activity compared to standard antibiotics, with Vibrio showing greater sensitivity to the Y@AC@ZnO NPs than Pseudomonas and E. coli.