Green synthesis of silver and copper-doped zinc oxide nanoflowers using Leucophyllum frutescens leaf extract for photodegradation of methylene blue dye and antibacterial applications†

Abstract

The present work unveils a process to synthesize silver (Ag) and copper (Cu) doped zinc oxide (ZnO) nanoflowers for photocatalytic and antibacterial applications. Leucophyllum frutescens leaf extract (LFLE) was used for the rapid and efficient green synthesis of nanoparticles (NPs). The current study provides new insight into the fabrication of uniform exotic NPs with tunable size and shape that control their photocatalytic and therapeutic potential. UV-visible and photoluminescent spectroscopy exhibited the optical properties. The energy bandgap of 3.36 eV in the ZnONPs was reduced to 3.26, 3.21, and 3.24 eV, in Ag@ZnONPs, Cu@ZnONPs, and Ag–Cu@ZnONPs, respectively as calculated from the Tauc plots. Field-emission scanning electron microscope and high-resolution transmission electron microscope images revealed the flower-shaped morphology of the NPs. At the same time, energy dispersive spectra and elemental mapping confirmed the presence of Zn, O, Ag, and Cu in the respective NPs. X-ray diffraction confirmed the crystalline nature with the average crystallite size being 12.75 nm, 11.22 nm, 13.14 nm, and 13.23 nm for ZnONPs, Ag@ZnONPs, Cu@ZnONPs, and Ag–Cu@ZnONPs. Photocatalytic degradation of methylene blue dye was maximum in the Ag–Cu@ZnONPs that closely fitted with the pseudo-first-order reaction kinetics. Additionally, the Ag@ZnONPs with a higher aspect ratio due to smaller size resulted in superior antibacterial activity and synergy with antibiotics against Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa. The results confirm the nanobiotechnological potential of L. frutescens which can be used for environmental remediation.