Double Layer\nSiO<sub>2</sub>‑Coated Water-Stable\nHalide Perovskite as a Promising Antimicrobial Photocatalyst under\nVisible Light

Halide perovskite nanocrystals (HPNCs)\nhave emerged as promising\nmaterials for various light harvesting applications due to their exceptional\noptical and electronic properties. However, their inherent instability\nin water and biological fluids has limited their use as photocatalysts\nin the aqueous phase. In this study, we present highly water-stable\nSiO<sub>2</sub>-coated HPNCs as efficient photocatalysts for antimicrobial\napplications. The double SiO<sub>2</sub> layer coating method confers\nlong-term structural and optical stability to HPNCs in water, while\nthe in situ synthesis of lead- and bismuth-based perovskite NCs into\nthe SiO<sub>2</sub> shell enhances their versatility and tunability.\nWe demonstrate that the substantial generation of singlet oxygen via\nenergy transfer from HPNCs enables efficient photoinduced antibacterial\nefficacy under aqueous conditions. More than 90% of <i>Escherichia\ncoli</i> was inactivated under mild visible light irradiation\nfor 6 h. The excellent photocatalytic antibacterial performance suggests\nthat SiO<sub>2</sub>-coated HPNCs hold great potential for various\naqueous phase photocatalytic applications.