ZnO@NiO nanoparticles green synthesis, characterization, and catalytic application for biological and environmental

In this study, ZnO@NiO core-shell nanoparticles were successfully fabricated utilizing the pulse laser ablation in liquid (PLAIL) process. An Nd: YAG laser with a wavelength of 1064 nm and various laser energies (350,550,850) mJ/pulse was used to create the nanoparticles. The optical and physical properties, as well as the impact of laser energy were studied. Dynamic light scattering (DLS), atomic force microscopy (AFM), scanning electron microscopy (SEM), Transmission Electron Microcopy (TEM), UV-Vis spectroscopy, X-ray diffraction (XRD), and Contact angle (CA) measurements were used to characterize the nanoparticles. The optical and structural analyses proven the formation of ZnO@NiO nanoparticles with high crystallinity, uniform distribution, excellent colloidal stability and increased surface area. The results showed that the optical band gap energy of pure ZnO decreased when NiO nanoparticles are utilized as shells for zinc oxide nanoparticles. The nanoparticles exhibited a spherical shape and a uniform distribution, with an average size of around 27.72 nm and high surface roughness. The zeta potential of ZnO@NiO NPs was (-37) mV, referring excellent stability of the nanoparticles. The CA of the NPs in the suspension was low between 60° and 65°. The antibacterial efficiency of ZnO@NiO NPs against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, as well as their photocatalytic activity in the degradation of methylene blue (MB) dye was comprehensively assessed. The ZnO@NiO nanoparticles demonstrated potent antibacterial action against E. coli and S. aureus, as well as effective photocatalytic dissolution of the MB dye. The antibacterial efficiency was notably higher against S. aureus than E. coli. This can be attributed to the more complex structure of bacterial cell walls. The creation of ZnO@NiO core/shell heterojunction greatly decreased the rate of recombination of the photoinduced electron-holes pairs, prolonged carrier lifespan and effective charge separation. These features promoted the production of reactive oxygen species (ROS) upon sunlight exposure, which oxidizes MB dye molecules effectively and showed high degradation efficacy over time. These results demonstrate the potential of ZnO@NiO nanomaterials prepared by the ecologically friendly PLAIL method as an extremely attractive option for utilize as antibacterial agents and photocatalysts in biomedicine and water treatment applications.