Plasmon-Sensitized Silica-Titanium Aerogels as Potential Photocatalysts for Organic Pollutants and Bacterial Strains

Photocatalysis reactions are of great interest as an effective tool against the profusely increasing population of antibiotic-resistant bacteria species. In particular, the promising evidence on plasmon-sensitized titanium dioxide (TiO₂) photocatalysis inspired us to investigate their antibacterial activity stemming from the photogenerated reactive oxygen species (ROS). Herein, TiO₂ nanostructures were grown in situ within a silica (SiO₂) aerogel matrix with high surface area and porosity, and their ROS-related phototoxic effects against Escherichia coli bacteria were investigated under solar- and visible-light irradiations. Photodegradation profiles obtained from Rhodamine B (RhB) organic dye used as a chemical probe proved that the types of ROS produced by SiO₂/TiO₂ aerogels varied depending on the electromagnetic spectrum portion that was used during material irradiation. Further, the SiO₂/TiO₂ aerogel matrix was decorated with silver-gold nanostars (Ag@Au NSs) to enhance its photocatalytic efficiency under visible light irradiations. Our design showed that plasmon-enriched composite aerogels efficiently boosted ROS production under visible light exposures and that the structures containing Ag@Au NSs showed a much more effective antibacterial effect compared to their counterparts.