Synthesis of ZnO nanoparticles with different morphologies using a microwave-based method and their antimicrobial activity

Zinc oxide nanoparticles (ZnONPs) are versatile nanomaterial that has consistently attracted research attention. This work presents a simple and cost-effective method for synthesizing ZnONPs using a microwave-based method. ZnONPs with different morphologies can be obtained by varying the sodium hydroxide (NaOH) reactant concentration. The synthesized products were morphologically and structurally investigated using field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray diffractometry (XRD). Additionally, the optical characteristics of the synthesized products were confirmed with UV–vis and Raman spectroscopy. The UV–vis spectra exhibit a prominent absorption band characteristic of ZnO. The FTIR spectra of ZnONPs in the 300–4,000 cm −1 range consist of bands corresponding to specific functional groups of biomolecules and metal oxides. The obtained XRD diffraction peaks can be assigned to a hexagonal wurtzite ZnO structure. The FTIR absorption peaks in the 495–850 cm −1 range confirm the structure of ZnONPs. According to the antimicrobial testing results, the products show growth inhibition against Gram-positive Staphylococcus aureus and Bacillus subtilis , as well as Gram-negative Escherichia coli and Klebsiella pneumoniae bacteria. Therefore, ZnONPs of all morphologies could be applied as antimicrobial agents.