Facile fabrication of Ag/C-TiO2nanoparticles with enhanced visible light photocatalytic activity for disinfection of Escherichia coli and Enterococcus faecalis

Abstract

This work aimed to investigate the promotive effect of Ag modification on C-TiO₂ for visible light photocatalytic disinfection of microorganisms. Ag/C-TiO₂ was prepared by a facile one-step synthesis approach through thermal oxidation of AgNO₃-impregnated TiC precursor. The self-doped carbon exists as both interstitial and substitutional carbon to collectively enhance the visible light photocatalytic absorption. The loaded silver nanoparticles were uniformly distributed on the TiO₂ surface in the Ag⁰ metallic state, further enhancing the visible light absorption due to surface plasmon resonance yet inhibiting the charge carrier recombination by conduction band electron trapping. The band structure and a tentative visible light photocatalytic disinfection mechanism of Ag/C-TiO₂ with four pathways were thus proposed, and the enhanced visible light photocatalytic performance was demonstrated for disinfection of Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) in comparison with C-TiO₂. This improvement was more pronounced with increasing Ag loading in the range of 0.5–5.0 wt%, which can be attributed to the improved visible light absorption and good charge carrier separation due to Ag modification as well as to the inherent bactericidal effect of metallic Ag.