Antibacterial and photocatalytic activities of sonochemically prepared ZnO and Ag–ZnO

ZnO and Ag–ZnO (0.5 at.%) nanocrystals have been prepared by sonochemical method and characterized by X-ray diffraction, energy dispersive X-ray analysis, scanning electron micrographs, UV–visible diffuse reflectance spectra, photoluminescence spectra, and impedance spectra. Ag-doping sharpens the band gap absorption, enhances the visible emission and increases the charge transfer resistance. The synthesized ZnO photocatalytically detoxifies cyanide in alkaline medium. The bactericidal activities of the prepared oxides, tested with Escherichia coli, are larger than that of commercial ZnO nanoparticles (Sigma–Aldrich). While the antibacterial efficiencies of the prepared ZnO and Ag–ZnO do not differ significantly, their photocatalytic activities to degrade dyes, tested with methyl orange, rhodamine B, and methylene blue, could not be generalized; photocatalysis is also substrate specific. Further, agglomeration of the nanoparticles in dye solution may lead to such results.

Research highlights▶ Sonochemically prepared ZnO and Ag–ZnO show larger bactericidal activity. ▶ Ag-doping sharpens band gap absorption. ▶ Ag-doping enhances visible emission. ▶ Ag-doping increases charge transfer resistance. ▶ Photocatalytic activities of ZnO and Ag–ZnO to degrade dyes also depend on the dye.