Visible-to-UVC driven upconversion photocatalyst sterilization efficiency and mechanisms of β-NaYF4: Pr3+, Li+@BiOCl with a core-shell structure.

UVC (wavelength < 280 nm) has a wide range of applications in the field of water disinfection due to its excellent bactericidal performance. In this work, we synthesized an upconversion luminescent material, β-NaYF4: Pr3+, Li+ (NYF), which can generate UVC, and compounded it with a BiOCl photocatalyst to synthesize β-NaYF4: Pr3+, Li+@BiOCl (NYF-Bi) with a core-shell structure. The NYF-Bi composite material can be driven under visible light and has high photocatalytic activity. The bactericidal performance of NYF and NYF-Bi were evaluated using Escherichia coli, Staphylococcus aureus, Shigella and Salmonella. The NYF-Bi composite material killed 99.99% of E. coli under visible light (λ ≥ 420 nm) within 180 min and maintained high germicidal efficacy after 4 cycles. Finally, we deduced the sterilization mechanism of the NYF-Bi composite material through carrier dynamics studies and catching agent experiments. The death of bacteria was mainly caused by UVC light and active species, including h+, OH, and O- 2. This research provides a new material for water disinfection.