A Multifunctional Biocide/Sporocide and Photocatalyst Based on Titanium Dioxide (TiO₂) Codoped with Silver, Carbon, and Sulfur

Composite nanostructured samples of Ag (0.5−20%)/(C, S)-TiO₂ were synthesized and characterized by EDX, XRD, FT-IR, UV−vis, BET, XPS, and zeta potential measurements. Photocatalytic and biocidal tests revealed that the amount of the codoped silver (Ag⁺) in (C, S)-TiO₂ played a crucial, distinctive role in the photodegradation of gas-phase acetaldehyde as well as in the inactivation of Escherichia coli cells and Bacillus subtilis spores. Very interestingly, Ag/(C, S)-TiO₂ nanoparticles (crystallite size <10 nm) have shown very strong antimicrobial properties without light activation against both E. coli (log kill >8) and B. subtilis spores (log kill >5) for 30 min exposures, compared with P25-TiO₂. Thus, for the first time, we have demonstrated that titanium dioxide (an environmentally friendly photocatalyst) codoped with silver, carbon, and sulfur can serve as a multifunctional generic biocide as well as a visible light activated photocatalyst.