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

Abstract

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 Escherichia 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 .