Application of Two-dimensional P-type ZnO Powder Illuminated By Visible Light for the Inhibition of Gram-positive and Gram-negative Bacteria in Water

Abstract

Bacteria affect food quality in developing countries by spreading through contaminated soils and water. Antibiotics are used indiscriminately to eliminate Gram-positive and Gram-negative bacteria, with varying degrees of success. The use of nanomaterials with bactericidal properties can minimize the overuse of antibiotics. In this study, a two-dimensional p-type ZnO powder was successfully synthesized and its bactericidal properties were demonstrated. The XRD and Raman spectroscopy results indicated the presence of wurtzite-phase ZnO with Oi as the predominant native defect, resulting in p-type conductivity. SEM analysis confirmed the two-dimensional morphology, and optoelectronic characterization revealed a bandgap of 3.17 eV. Despite this high bandgap value, a plasmonic effect was generated on the surface of two-dimensional ZnO, which enhanced its bactericidal properties when the powders were in contact with bacteria. From an initial colony level of 5.5 × 105 CFU/mL, a significant decrease in the number of Gram-positive bacteria to 1.15 × 105 CFU/mL was observed, whereas the number of Gram-negative bacteria slightly increased to 1.45 × 106 CFU/mL. The observed inhibition rates were higher than those achieved with the broad-spectrum antibiotic, as validated in this study. The use of two-dimensional ZnO may provide a sustainable solution for the eradication of waterborne pathogens using visible light alone.