Synthesis, characterization, and the influence of energy of irradiation on optical properties of ZnO nanostructures

Zinc oxide nanoparticles (NPs) are synthesized by the sol–gel method for optoelectronics, photonic, and medical applications. The as-synthesized NPs are irradiated with lasers with wavelengths of 1064 nm and 532 nm in an attempt to improve the particles' structural and functional properties. The NPs are characterized by means of X-ray diffraction, scanning and transmission electron microscopy techniques, atomic force microscopy, and ultraviolet–visible spectroscopy. The structural analysis shows that the particles have a polycrystalline hexagonal structure of the space group (P6(3)mc). The average crystallite size of nanoparticles varies in the range of 13–15 nm after and before irradiation by a laser beam. The morphological characterization revealed the formation of agglomerates of NPs in the range of 42–46 nm A shift is observed in the absorption spectra after irradiation with a laser beam. This shift is due to the effect of irradiation on the sample’s electronic structure. This effect is confirmed by a decrease in the bandgap energy. The optical parameters are also deduced and discussed. The irradiation of ZnO nanoparticles by laser beams of wavelength 1064 nm and 532 nm decreases the size of the crystallites which increases their antibacterial activity. The biological activity of the NPS and in improving the efficacy of antibiotics are tested and analyzed. Results emphasized the positive role of ZnO-NPs in the above-mentioned application.