Enhanced Antibacterial Activity and Photo-Catalytic Properties of ZnO Nanoparticles: <i>Pedalium Murex</i> Plant Extract-Assisted Synthesis

Abstract

Semiconductor ZnO samples with two different morphologies such as nanoparticles (ZnO-NPs) and nano-sheets (ZnO-NSs) was successfully prepared by microwave heating (MHM) and modified sol-gel (SGM) method, respectively using <i>Pedalium Murex</i> plant extract as the bio-reducing agent. Structural, purity and morphology of the samples was examined by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. Optical property analysis and band gap calculation were carried out by UV-Visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy techniques. Kubelka-Munk method was used to measure band band gap of the samples and it shows 3.42 eV and 3.23 eV for ZnO-NPs and ZnO-NSs, respectively. The antibacterial activities of ZnO-NPs and ZnO-NSs against both gram positive (<i>Bacillus subtilis</i>, <i>Staphylococcus aureus</i>) as well as gram negative bacteria (<i>Proteus mirabilis</i>, <i>Salmonella typhi</i>) were tested by modified disc diffusion method and showed important antibacterial activity against <i>P. mirabilis</i> and <i>S. typhi.</i> The photocatalytic activity of ZnO nano-catalysts (ZnO-NPs and ZnO-NSs) for the degradation of methylene blue (MB) dye was studied under solar lighting and the results showed that the samples ZnO-NPs with smaller particle size considerable degradation of MB than ZnO-NSs.