Hydrothermal-assisted green synthesis of Ag-doped ZnO nanoparticles using Punica granatum peel extract for enhanced photocatalytic and antibacterial applications

Abstract

In the present study, ZnO nanoparticles doped with 5 and 8% Ag were synthesized using a green method with Punica granatum peel extract. Characterization of ZnO nanoparticles revealed a sharp peak in the UV–Vis spectra at 360–380 nm, spherical morphology in scanning electron microscope analysis, and microsphere edges with clear fringes and separations of 0.329 and 0.252 nm in transmission electron microscope analysis. The synthesized nanoparticles were utilized to investigate the photocatalytic degradation of crystal violet (CV) and methyl orange (MO) dyes in an aqueous environment under UV irradiation. The study demonstrated that 5% Ag-doped ZnO nanoparticles are highly efficient photocatalysts, achieving a 93% reduction in MO and an 88% decrease in CV concentration within a short duration of 90 min. The 5% Ag-doped ZnO composite exhibited a rate constant of 0.046 min⁻¹, significantly higher than that of pure ZnO (0.027 min⁻¹), while the 8% Ag-doped ZnO showed a slight decline in photocatalytic activity with a rate constant of 0.035 min⁻¹). Additionally, the antibacterial activity of the synthesized nanoparticles was tested against various Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. The 5% Ag-doped ZnO nanoparticles exhibited significantly enhanced antibacterial activity, as evidenced by a larger zone of inhibition, compared to both pristine ZnO- and 8% Ag-doped ZnO, indicating that 5% is the optimal doping concentration for maximum antibacterial efficacy. These findings highlight the strong antibacterial potential of the synthesized Ag-doped ZnO nanoparticles, with Punica granatum peel extract playing a critical role in increasing both antibacterial and photocatalytic activity.