An experimental and theoretical study on the photocatalytic antibacterial activity of boron-doped TiO2 nanoparticles

Boron-doped titanium dioxide nanoparticles (B–TiO2 NPs) were prepared by a sol-gel method. The physicochemical properties of B–TiO2 NPs were characterized by X-ray diffraction, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy and photoluminescence spectroscopy. The band structure and electrical properties of B–TiO2 NPs were investigated using the first-principle. The effects of the concentration gradient of doping B ions on the photocatalytic antibacterial activity of B–TiO2 NPs under visible-light irradiation were investigated by the inhibition zone method and the shaking flask method. The experimental results show that B–TiO2 NPs are mainly composed of the anatase phase, but no B-related phase was observed. With the increase of the doping amount of boron ions, the particle size decreases and the specific surface area increases. B atoms mainly exist in the form of substitutional dopant and interstitial dopant. Theoretical calculations reveal that B atoms in the TiO2 matrix exist much more easily as interstitial dopant, but B–TiO2 NPs composed of B substituted dopant have better photocatalytic performance. The results of the antibacterial assays show that B–TiO2 NPs have strong antibacterial activities and some bactericidal activities. Finally, the mechanism of the antibacterial activity of B–TiO2 NPs are examined.