Photocatalytic inactivation of Escherischia coli under UV light irradiation using large surface area anatase TiO(2) quantum dots

In this study, high specific surface areas (SSAs) of anatase titanium dioxide (TiO(2)) 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 TiO(2) QDs of approximately 2 nm size have high crystallinity with anatase phase. Optical properties showed that the energy band gap (E(g)) of as-prepared TiO(2) QDs was 3.60 eV, which is higher than the standard TiO(2) band gap, which might be due to the quantum size effect. Raman studies showed shifting and broadening of the peaks of TiO(2) QDs due to the reduction of the crystallite size. The obtained Brunauer–Emmett–Teller specific surface area (381 m(2) g(−1)) of TiO(2) QDs is greater than the surface area (181 m(2) g(−1)) of commercial TiO(2) nanoparticles. The photocatalytic activities of TiO(2) QDs were conducted by the inactivation of Escherischia coli under ultraviolet light irradiation and compared with commercially available anatase TiO(2) nanoparticles. The photocatalytic inactivation ability of E. coli was estimated to be 91% at 60 µg ml(−1) for TiO(2) QDs, which is superior to the commercial TiO(2) nanoparticles. Hence, the present study provides new insight into the rapid synthesis of TiO(2) QDs without any annealing treatment to increase the absorbance of ultraviolet light for superior photocatalytic inactivation ability of E. coli.