Enhanced green luminescence properties of cu doped ZnO nano-flowers and their improved antibacterial activities

Abstract

The copper doped ZnO (CuxZn1-xO, where x = 0, 0.01, 0.02, 0.04, 0.05) nanoflowers were produced by using co-precipitation process. Hexagonal wurtzite nanocrystalline phase of both pure and Cu-doped samples was confirmed by X-ray diffraction analysis. Field emission scanning electron microscopy results confirmed the emergence of fully dispersed nanoflower like morphologies in the Cu-doped ZnO and uniform dispersion of particles. Band gap energies of the prepared samples were calculated using the Tauc?s plot. All of the generated samples? room temperature photoluminescent spectra show two emission peaks, one excitonic peak in the UV region and another broad defect level peak in the visible area. The yellow and green luminescence characteristics of both pure and doped samples were analysed via the PL spectra in visible light region, making them appropriate for optoelectronic applications. The antibacterial potential of the produced nanostructures against the bacterial strains of Enterococcus Faecalis (gram positive) and Pseudomonas Aeruginosa (gram negative) were assessed. When compared to the pure ZnO nanostructures, the doped samples exhibit enhanced antibacterial activity. For the samples with 5 at.%Cu, the greatest zone of inhibition against Pseudomonas Aeruginosa was noted to be 25mm. For the samples doped with 5 at.% Cu, the largest zone of inhibition against Enterococcus Faecalis was 21mm. The findings indicate that the obtained samples have higher antibacterial potential against gram negative than gram positive bacteria. The prepared doped ZnO nanoflowers were therefore recommended as excellent green nanophosphors for the production of white LEDs and effective nanoantibiotics against gram-negative bacteria.