Synergistic behavior between the plasmonic Ag metal and the mesoporous β-Bi2O3/SiO2 heterostructure for the photocatalytic destruction of bacterial cells under simulated sunlight illumination: Schottky junction electron-transfer pathway

Abstract

Undoubtedly, one of the most attractive alternative wastewater disinfection techniques is visible-light-driven photocatalysis. Unfortunately, the fast recombination of charge carriers still limits its practical application. This limitation can be addressed by developing a plasmon-induced nanocomposite photocatalyst by hybridizing the semiconductor with co-catalyst metallic nanoparticles (NPs). Herein, a Schottky junction Ag/β-Bi2O3/SiO2 (A/BO/SO) nanocomposite was constructed via a multistep method involving the immobilization of β-Bi2O3 and Ag NPs on the nanosilica surface. The characterization techniques demonstrated the ability of Ag/β-Bi2O3/SiO2 to extend the visible light absorption and boost the charge separation efficiency through the plasmonic actions of silver metal. It was revealed that the Ag/β-Bi2O3/SiO2 nanocomposite exhibited improved antimicrobial performance against the Staphylococcus aureus pathogen, in which 7-log of bacterial cells were inactivated within 120 min under simulated solar light illumination. These outcomes were ascribed to the synergistic impact of silica support, β-Bi2O3 semiconductor, and plasmonic Ag metal (electron acceptor) in one system. Besides, the Ag/β-Bi2O3/SiO2 nanocomposite displayed remarkable structural stability after five inactivation cycles, which is attributed to the mesoporous structure of the silica support. The mechanism studies revealed that •OH and •O2− are the main reactive species that drive the disinfection reaction, and the electrons' separation behavior is well matched with Schottky junction pathways. In conclusion, this work provided an efficient and stable photocatalyst with minimum energy consumption that can be applied in water disinfection for the removal of pathogenic microorganisms.