Rapid microwave-assisted synthesis of ZnO nanoflowers, characterization and antibacterial activity

Abstract In this work, zinc oxide (ZnO) flower-like nanostructures were synthesized using a rapid microwave-assisted method, and their antibacterial activity was evaluated against Escherichia coli ( E. coli ). The composition, crystal structure and morphology of the as-synthesized ZnO nanostructures were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and nitrogen physisorption analysis, Brunauer–Emmett–Teller (BET). Electron microscopy confirmed the flower-like morphology, revealing structures ranging from 0.4 to 1.2 μm in size, that were composed of individual nanoparticles with sizes between 27 and 49 nm. The XRD analysis revealed a pattern of sharp peaks, confirming a highly crystalline, pure wurtzite phase with an average crystallite size of 24 nm. The BET analysis indicated a high specific surface area of 14.60 m 2 /g and a mesoporous structure with an average pore size of 10.42 nm, which provides numerous accessible active sites for surface interactions. The ZnO nanostructures demonstrated excellent antibacterial activity against E. coli , as evidenced by a substantial inhibition zone of around 24 mm in total diameter around the pellet. Consequently, the high surface area, hierarchical morphology and proven antibacterial efficacy of the prepared ZnO nanostructures make them highly promising candidates for applications in advanced wastewater treatment and high-performance gas sensing nanodevices.