Study of structural, antibacterial, and photocatalytic activities of plant extract-assisted Ag/ZnO nanoparticles prepared by green-assisted co-precipitation

In the present work, pure ZnO and Ag-modified ZnO nanoparticles were synthesized using a co-precipitation method assisted by Crocus sativus leaf extract as a natural reducing agent and a stabilizer. The X-ray diffraction pattern revealed that a hexagonal wurtzite structure was formed and the average crystallite size the range of 20–25 nm. As one can see, the energy of the band gaps decreased from 3.18 eV (pure ZnO) to 2.26 eV in the case of Ag-doped samples. It shows that the doping of Ag in pristene ZnO leads to an effective decrease the band gap of composite material.The photocatalytic activity was assessed by the degradation of methylene blue (MB) dye in the presence of the sun rays, where 10% Ag-doped ZnO had a maximum degradation efficiency of 98% after 120 min. The increased activity is explained by the better separation of charges and the higher production of reactive oxygen species (ROS) because of the addition of Ag. Moreover, the Ag-doped ZnO nanoparticles showed a high level of antibacterial activity against Escherichia coli, and the maximum zone of inhibition was 35 mm. The new aspect of this work is that the photocatalytic and antibacterial properties are synergistically enhanced through environmentally-friendly green synthesis and optimized Ag doping. These results demonstrate the possible use of Ag-doped ZnO nanoparticles in environmental remediation and biomedical applications.