Visible-light photocatalysis of organic contaminants and disinfection using biomimetic-synthesized TiO2-Ag-AgCl composite

The design and production of highly efficient photocatalysts are required to resolve environmental issues. Herein, a TiO2-Ag-AgCl photocatalyst is fabricated using polydopamine-mediated biomimetic mineralization. The as-prepared composite is able to degrade Rhodamine B (RhB) and ciprofloxacin (CIP) efficiently, and has strong bactericidal capability against E. coli upon the irradiation of visible light. Moreover, TiO2-Ag-AgCl composite can efficiently destruct existing E. coli biofilm. The trapping experiment and electron paramagnetic resonance (ESR) analysis show that h+ and O2– are dominating reactive oxygen species (ROS) during the elimination of organic pollutants and E. coli. Also, the cellular response to ROS damage is determined using RNA-seq transcriptomics analysis. Some chemotaxis-related outer membrane genes, such as ompA, ahpC, ypfH and ompX, were up-regulated; especially ypfH is first found to be related to cellular defense against photo-disinfection. The current work presents a novel method to synthesize a promising photocatalyst to degrade organic pollutants and disinfect bacteria in water.