Synthesis and Characterization of Fe-Zn Bimetallic Nanoparticles via Two-Step Laser Ablation and Their Antibacterial Activity

In this study, Nd: YAG laser at a wavelength of (1064 nm), energies of (300 and 400 mJ), and a pulse repetition rate of (3 Hz) was used to synthesize metallic nanoparticles from iron and zinc individually using a one-step pulsed laser ablation approach, followed by the two-step synthesis of bimetallic nanoparticles. The physical properties of the synthesized nanoparticles were then investigated using UV-visible (UV-Vis), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) techniques. The results of characterization of the obtained NPs confirmed the formation of core-shell nanocomposites, as evidenced by the increased absorbance intensity of these samples, resulting from increased size averages and surface roughness, in addition to the formation of the Fe2O4Zn nanocomposite resulting from the two-step ablation process. The increased absorbance and size of the nanoparticles suggest an enhanced interaction with light, which could be advantageous for applications requiring strong optical properties. UV-Vis analysis showed that the ablation energy (400 mJ) resulted in higher absorption intensity for all samples and that the absorption intensity of the core-shell nanoparticles was the highest in comparison. The energy gap values generally ranged within the range (3.2 – 3.4 eV). XRD results revealed a polycrystalline structure with a hexagonal phase for both iron oxide nanoparticles and zinc oxide nanoparticles, the average crystalline sizes (59.6 nm) and (73.1 nm), respectively, and a cubic phase for the bimetallic (core-shell) nanocomposites, with increased average sizes of (85.2 nm) and (82.12 nm). FESEM results showed rough surfaces for these nanoparticles, as well as the presence of clusters and agglomerates, with an average size within the nanoscale range (90 nm). This increase in size, in turn, led to increased absorption compared to iron oxide and zinc oxide nanoparticles. The nanoscale of the synthesized nanoparticles led to their antibacterial activity, as all synthesized nanoparticles showed an effect on two types of bacteria, one Gram-positive and the other Gram-negative, where the inhibition ranges ranged within the range (12 – 18 mm), which indicates that the structural and optical properties of the core-shell nanocomposites may contribute to their effectiveness as potential alternatives to traditional antibiotics to inhibit bacteria.