Improving the antibacterial efficiency of ZnO nanopowders through simultaneous anionic (F) and cationic (Ag) doping

• The paper deals with enhancement of antibacterial activity of ZnO nanopowders by a novel double doping.
• This is the first report on Ag + F doped ZnO nanopowder.
• All physical properties of the samples are correlated well with the antibacterial efficacy.

Ag and (Ag + F) doped ZnO nanopowders were synthesized using combustion method by varying the F doping level (5, 10, 15 and 20 at.%) and keeping a constant Ag doping level (2 at.%). The obtained samples were characterized for their structural, optical, surface morphological and antibacterial properties. XRD results showed that all the samples exhibited preferential orientation along the (101) plane. The variation in the crystallite size with the increase in F doping level is explained on the basis of the Zener pinning effect. FTIR and photoluminescence studies confirmed the incorporation of Ag and F into the ZnO lattice. The carrier concentration was found to increase with the increase in F doping level up to 10 at.% as evidenced by the blue shift in the NBE peak. From the studies, it was found that 10 at.% of F doping is optimal to achieve better antibacterial efficiency against three different bacteria viz. Staphylococcus aureus, Escherichia coli and Salmonella typhi. The influence of the shape and size of the ZnO:Ag:F nano grains on the antibacterial activity is analyzed using the SEM and TEM images.

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