Microbial inactivation kinetics and mechanisms of carbon-doped TiO₂ (C-TiO₂) under visible light

Highlights: • Carbon modified TiO₂ photocatalysts prepared by sol–gel methods. • C-TiO₂ was highly effective in the inactivation of L. monocytogenes. • C-TiO₂ was shown to be more synergistic inactivation effect under visible light. • C-TiO₂ be useful in the development of alternative disinfectants for environmental application. - Abstract: In this study, titanium dioxide nanoparticles doped with carbon (C-TiO₂) were synthesized by means of sol–gel methods, and the synthesis was verified by means of X-ray photoelectron spectroscopy. The nanoparticles' photocatalytic disinfection activity of Listeria monocytogenes was tested under UV and visible light. The observed inactivation levels for 150 min of visible light exposure with and without UV cutoff filters were 2.10 and 2.45 log, respectively. We also found that traditional reactive oxygen species had insignificant actions on C-TiO₂ photocatalysts and that L. monocytogenes inactivation in the C-TiO₂ system under visible light was induced in large part by the midgap states (h_mid⁺) that was produced photochemically from the visible light response. C-TiO₂ was found to accelerate bacterial inactivation (of L. monocytogenes) in the presence of visible light. Our data suggests that the C-TiO₂ may be useful in the development of alternative disinfectants for environmental applications.