How ambient reactive oxygen species regulation by Z-scheme heterojunction contributes to cell membrane damage and metabolism inhibition in solar-driven photocatalytic disinfection

Photocatalytic disinfection is of great interest due to its high environmental sustainability and low energy cost. However, the roles of catalyst structure and oxidation pathways in cell inactivation remain still unclear. Herein, flower-like BiOCl/BiOI was structured for photocatalytic Escherichia coli (E. coli) extermination, highlighting the roles played by the Z-scheme heterojunction and reactive oxygen species (ROS) regulation. The hydroxyl radicals generated by BiOCl was successfully combined with superoxide radicals and singlet oxygen generated by BiOI in BiOCl/BiOI structuring. Such a synergistic effect was optimized by ratio of Cl: I = 1: 1, which eliminated the E. coli most efficiently, achieving complete and recyclable disinfection (over 99 %) in 30 min. The cell inactivation was achieved jointly by intracellular ROS accumulation, the cell membrane damage, and inhibition of membrane repair. The oxidative stress from ambient ROS was conducted to intracellular imbalance, exceeding the capacity of intracellular regulation. These results confirm that the synergistic effect of ROS can be regulated to reach the optimal ambience for killing bacteria, analyze the mechanism of cellular disturbance in photocatalytic disinfection. This work connected the regulation of photocatalytic effects via different oxidation pathways to the mechanisms of cell deactivation.