Efficient bacterial inactivation with Z-scheme AgI/Bi₂MoO₆ under visible light irradiation

A novel Z-scheme AgI/Bi₂MoO₆ hybrid photocatalyst was fabricated via a solvothermal-precipitation approach to disinfect bacteria in water. Powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopic (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscope (HRTEM), UV-vis diffuse reflectance spectra (DRS), as well as photoluminescence spectra (PL) were employed to characterize the fabricated photocatalyst. Due to the stronger redox potential and better separation of charge carriers induced by the Z-scheme structure, the optimal synthesized AgI/Bi₂MoO₆ exhibited excellent disinfection activity towards both Gram-negative strain Escherichia coli (E. coli) and Gram-positive strain Staphylococcus aureus (S. aureus) under visible light irradiation. 5.0 × 10⁷ CFU mL^-1 of E. coli and S. aureus cells were completely disinfected within 30 min and 90 min, respectively. Ag⁺ ions did not contribute to the disinfection activity, while active species including h⁺, O₂^-, e^-, and H₂O₂ contributed to the cell inactivation. By changing the interaction force and being involved in the photocatalytic reactions, the common anions (Cl^-, NO₃^-, SO₄^2-, and H₂PO₄^-) would affect the disinfection activity. Moreover, AgI/Bi₂MoO₆ exhibited effective disinfection activity in four consecutive reused cycles. Thus, AgI/Bi₂MoO₆ could be used as a promising photocatalyst for water disinfection.