Sulfur-doped titanium dioxide exhibits a strong visible-light-induced antibacterial effect. The new photocatalyst can effectively kill Micrococcus lylae, a common Gram-positive bacterium. The relationship between sulfur concentration and the bactericidal activity of S-doped TiO2 was investigated. Results from DMPO spin-trapping electron spin resonance measurements confirm the formation of hydroxyl radicals, which is the origin of the considerable bactericidal activity under visible light irradiation.

Urgent development of effective and low-cost disinfecting technologies is needed to address the problems caused by an outbreak of harmful microorganisms. In this work, we report an effective photocatalytic disinfection of E. coli K-12 by using a AgBr-Ag-Bi(2)WO(6) nanojunction system as a catalyst under visible light (lambda >or= 400 nm) irradiation. The visible-light-driven (VLD) AgBr-Ag-Bi(2)WO(6) nanojunction could completely inactivate 5 x 10(7) cfu mL(-1) E. coli K-12 within 15 min, which was superior to other VLD photocatalysts such as Bi(2)WO(6) superstructure, Ag-Bi(2)WO(6) and AgBr-Ag-TiO(2) composite. Moreover, the photochemical mechanism of bactericidal action for the AgBr-Ag-Bi(2)WO(6) nanojunction was investigated by using different scavengers. It was found that the diffusing hydroxyl radicals generated both by the oxidative pathway and the reductive pathway play an important role in the photocatalytic disinfection. Moreover, direct contact between the AgBr-Ag-Bi(2)WO(6) nanojunction and bacterial cells was not necessary for the photocatalytic disinfection of E. coli K-12. Finally, the photocatalytic destruction of the bacterial cells was directly observed by TEM images and further confirmed by the determination of potassium ion (K(+)) leakage from the killed bacteria. This work provides a potential effective VLD photocatalyst to disinfect the bacterial cells, even to destruct the biofilm that can provide shelter and substratum for microorganisms and resist to disinfection.