Ag bridged step-scheme MoS2/Bi4O5Br2 heterojunction for enhanced visible light driven photocatalytic disinfection activity

Photocatalytic disinfection is one of the emerging green technologies for pathogenic microorganisms inactivation in water. Herein, a novel step-scheme Ag QDs/MoS2/Bi4O5Br2 heterojunction was successfully synthesized by a facile mechanical assembly route and applied in disinfection under visible light irradiation. Comparing to the pristine Bi4O5Br2, the Ag QDs/MoS2/Bi4O5Br2 heterojunction displays superior photocatalytic disinfection ability. In particular, the 1-Ag QDs/MoS2/Bi4O5Br2 heterojunction exhibits the most powerful disinfection capacity, which can completely inactivate the 7-log10 cfu/mL bacterial under 120 min irradiation. Additionally, the photocatalytic disinfection mechanism was intensively investigated with several techniques, such as biological macromolecules electrophoresis, fluorescent staining, and EPR. In this system, the h+, ·OH, and ·O2− are the major reactive species that led to the broken of the cell membrane, leakage of intracellular biomolecules and final death of bacteria. Additionally, the enhanced photocatalytic disinfection ability of 1-Ag QDs/MoS2/Bi4O5Br2 heterojunction is attributed to the improved light capture ability, efficient migration and transfer of photogenerated charge carriers and larger specific surface area. This work provides a novel approach to design step-scheme Bi4O5Br2-based heterojunction for pathogenic bacteria disinfection with abundant solar light.