Green Encapsulation of Metal Oxide and Noble Metal ZnO@Ag for Efficient Antibacterial and Catalytic Performance

The increasing demand for multifunctional nanomaterials has highlighted the significance of environmentally sustainable synthesis methods. This study presents an innovative green and efficient approach to the encapsulation of green silver (Ag) nanoparticles with metal oxide of zinc (Zn) to produce ZnO@Ag nanocomposite (NC), employing aqueous neem extract as both a stabilizer and reducing agent. NCs are materials synthesized with two or more components, with at least one component falling in then nanometer scale. Such combined materials bring the properties of both components together, resulting in unique properties distinct from those of individual materials. Thus, this study provides a strong mechanistic approach to the biosynthesis process of nanocomposites and their antibacterial and catalytic activities. The one-pot biosynthesis, performed in an ultrasonicated bath, produced uniformly dispersed nanoparticles in 1 h, representing a quick and efficient way to synthesize nanocomposites. UV–vis spectra revealed a broad absorption peak (320–500 nm), confirming ZnO@Ag integration, while FTIR unveiled neem-derived polyphenolic groups as stabilizers; TEM and HRTEM highlighted spherical nanostructures (25 ± 3 nm) with crystalline SAED patterns and a bioprotective phytochemical coating. The chemical states and surface composition of the ZnO@Ag nanocomposites were analyzed through XPS. The produced ZnO@Ag NC exhibited remarkable antibacterial effectiveness, producing inhibition zones of 30 and 29 mm against Staphylococcus aureus and Pseudomonas aeruginosa, respectively. Furthermore, the nanocomposite exhibited exceptional catalytic activity, effectively decomposing methylene blue (MB) and methyl orange (MO) dyes by 96 and 93%, respectively. Overall, this study demonstrates an ultrasonic-assisted approach of combining the properties of Ag and Zn metal oxides that integrates exceptional antibacterial and catalytic efficacy while adhering to green chemistry principles. This research identifies ZnO@Ag nanocomposite as a transformative innovation for health and environmental applications, offering a sustainable solution to worldwide issues of antibiotic resistance and pollutant cleanup.