Synthesis and Characterization of the Ag-doped TiO2

In this study, the photo-deposition method was used to introduce Ag onto the surface of TiO2 to synthesize an Ag-TiO2 composite. The effects of the varying amounts of AgNO3 precursor and annealing time periods on the Ag content in the composites, as well as their antibacterial characteristics under visible light conditions were studied. SEM analysis revealed the spherical morphology of the Ag-TiO2 composite. Compared with TiO2, the Ag particles were too small to be observed. An XPS analysis of the Ag-TiO2 surface confirmed the Ag content and showed the peak intensities for elements such as Ag, Ti, O, C, and Si. The highest Ag content was observed when 33.3 wt.% of AgNO3 and an annealing time of 6 h were employed; this was the optimum annealing time for Ti-Ag-O bonding, in that the lowest number of O bonds and the highest number of Ag bonds were confirmed by XPS analysis. Superior antibacterial properties against Bacillus and Escherichia coli, in addition to the widest inhibition zones were exhibited by the Ag-TiO2 composite with an increased Ag content in a disk diffusion test, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%.