Photocatalytic inactivation ofEscherichia coliunder UV light irradiation using large surface area anatase TiO₂quantum dots

In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO₂) quantum dots (QDs) were successfully synthesized through a novel one-step microwave–hydrothermal method in rapid synthesis time (20 min) without further heat treatment. XRD analysis and HR-TEM images showed that the as-prepared TiO₂QDs of approximately 2 nm size have high crystallinity with anatase phase. Optical properties showed that the energy band gap (E_g) of as-prepared TiO₂QDs was 3.60 eV, which is higher than the standard TiO₂band gap, which might be due to the quantum size effect. Raman studies showed shifting and broadening of the peaks of TiO₂QDs due to the reduction of the crystallite size. The obtained Brunauer–Emmett–Teller specific surface area (381 m²g⁻¹) of TiO₂QDs is greater than the surface area (181 m²g⁻¹) of commercial TiO₂nanoparticles. The photocatalytic activities of TiO₂QDs were conducted by the inactivation ofEscherichia coliunder ultraviolet light irradiation and compared with commercially available anatase TiO₂nanoparticles. The photocatalytic inactivation ability ofE. coliwas estimated to be 91% at 60 µg ml⁻¹for TiO₂QDs, which is superior to the commercial TiO₂nanoparticles. Hence, the present study provides new insight into the rapid synthesis of TiO₂QDs without any annealing treatment to increase the absorbance of ultraviolet light for superior photocatalytic inactivation ability ofE. coli.