Biosafe Bi2O2Se ultrathin nanosheet for water disinfection via solar-induced photothermal synergistic effect.

Solar-induced sterilization via photothermal synergy has attracted enormous attention due to its zero-energy consumption and the elimination of hazardous chemical disinfectant. Herein, we successfully synthesized a super biosafety Bi2O2Se with crossed nanosheet structure (Bi2O2Se-CN) for the sterilization of Escherichia coli (E. coli) via solar-induced photothermal synergistic effect. In comparison to bulk Bi2O2Se, the lower light reflection and more efficient photogenerated charge carrier separation under visible-infrared light irradiation resulted in the excellent sterilization effect of Bi2O2Se-CN, with a sterilization efficiency of 99.9% under the synergistic effect of light and heat. The crossed ultrathin nanosheet structure and suitable band gap width of Bi2O2Se-CN are fundamental reasons for its enhanced light absorption and charge carrier separation efficiency. Mechanistic studies showed that Bi2O2Se-CN can completely inactivate bacteria via generating a large amount of reactive oxygen species (•O2-, •OH, and 1O2) to attack the cell membrane, which further resulted in the reduced activity of intracellular enzymes and the leakage of intracellular contents. The biosafety property of Bi2O2Se-CN was confirmed by in vivo toxicological evaluation on the mice model. This work provided new ideas for the design of more efficient, energy-saving, biocompatible and environmental friendly solar water purification projects.