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In the present study, we use commercial digitally printed ceramic tiles, functionnalized by AgNPs doped micro&#8722;TiO₂, to investigate the mechanism of Ag in the continouos photocatalytic antibacterial activity. The novelty of the research lies in the attempt to understand the mechanism of Ag, supported on TiO₂, able to exhibit the same antibacterial activity of a standard system containing Ag species, but here, totally embedded on the tile surface, and thus not free to move and damage the bacteria cell. UV/vis diffuse reflectance spectroscopy (DRS) of AgNPs&#8722;TiO₂ tiles indicated an enhanced visible light response, wherein a new absorption band was produced around 18,000&#8722;20,000 cm^&#8722;1 (i.e., in the 400&#8722;600 nm range) owing to the surface plasmon resonance (SPR) of AgNPs. The antibacterial photocatalytic experiments were conducted towards the inactivation of <i>E. coli</i> under solar light and indoor light. It was found that the degradation speed of <i>E. coli</i> in the presence of AgNPs&#8722;TiO₂ tiles is solar light-intensity depending. This justifies the semiconductor behavior of the material. Furthermore, the AgNPs&#8722;TiO₂ tiles exhibit a high ability for the inactivation of <i>E. coli</i> at a high load (10⁴&#8722;10⁷ colony-forming unit (CFU)/mL). Additionally, AgNPs&#8722;TiO₂ tiles showed a remarkable antibacterial activity under indoor light, which confirms the good photocatalytic ability of such tiles. On the basis of the reactive oxygen species (ROS) quenching experiments, O₂^{&#8226;&#8722;} species and h⁺ were more reactive for the inactivation of <i>E. coli</i> rather than ^&#8226;OH species. This is because of the different lifetime (bacteria are more likely oxidized by ROS with longer lifetime); in fact, O₂^{&#8226;&#8722;} and h⁺ exhibit a longer lifetime compared with ^&#8226;OH species. The generation of H₂O₂ as the most stable ROS molecule was also suggested.