Bactericidal activity and mechanism of Ti-doped BiOI microspheres under visible light irradiation

Higher conduction band energy induced better visible light driven disinfection activity of BiOI by Ti doping. [Display omitted] •Ti doped BiOI microspheres contained strong VLD disinfection property.•The electronic structure of BiOI was tuned by Ti doping.•Optimal Ti doping amount was determined.•h+, O2−, e− and H2O2 were found to play important roles. Ti doped BiOI microspheres were successfully synthesized through a solvothermal method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS) spectroscopy, respectively. The as-synthesized microspheres had 3D hierarchical structures, and the morphologies and visible-light-driven (VLD) disinfection performances were found to be determined by the amount of loaded Ti. The incorporation of Ti in the lattice of BiOI broadened the band gap of BiOI and enhanced the VLD disinfection activity. Ti doped BiOI microspheres with the optimal Ti content exhibited excellent antibacterial performances against both representative Gram-negative and Gram-positive strains, which completely inactivated 3.0×107CFUmL−1E. coli in 24min and 3.0×106CFU mL−1S. aureus in 45min, respectively. Active species including h+, e−, O2− and H2O2 were found to play important roles in disinfection system. Moreover, the damage of cell membrane and emission of cytoplasm directly led to the inactivation.