With the aim to enhance photocatalytic properties and anti-Ecoli bacteria abilities of TiO2 thin films; hierarchical heterogeneous nanostructured ZnO/TiO2 (HNs) films were deposited by DC magnetron sputtering. The obtained results showed that both the photocatalytic performance and anti - Ecoli bacteria ability of HNs films exhibited enhancement in comparison with standard TiO2 films. This enhancement was explained due to the reduction of the electron - hole recombination and the red shift of absorption edge of the HNs films. | Communications in Physics, Vol. 23, No. 1 (2013), pp. 90-96 PREPARATION AND CHARACTERIZATION OF PHOTOCATALYTIC PERFORMANCE OF HIERARCHICAL HETEROGENEOUS NANOSTRUCTURED ZnO/TiO2 FILMS MADE BY DC MAGNETRON SPUTTERING LE PHUC QUY AND VU THI HANH THU Faculty of Physics and Engineering Physics, University of Science of Ho Chi Minh City, Vietnam National University Ho Chi Minh City Abstract. With the aim to enhance photocatalytic properties and anti-Ecoli bacteria abilities of TiO2 thin films; hierarchical heterogeneous nanostructured ZnO/TiO2 (HNs) films were deposited by DC magnetron sputtering. The obtained results showed that both the photocatalytic performance and anti - Ecoli bacteria ability of HNs films exhibited enhancement in comparison with standard TiO2 films. This enhancement was explained due to the reduction of the electron - hole recombination and the red shift of absorption edge of the HNs films. I. INTRODUCTION The photoactivity of TiO2 has been extensively studied and attracted a wide attention for the past two decades and, now it is being extensively applied in the photocatalytic degradation of organic pollutants in water and air, photocatalytic disinfection of bacteria, manufacturing anti-fog and self-cleaning glass etc [1]. Fig. 1. Schematic illustration of the three stages in the process of E. coli photocatalytic microbial inactivation on the photocatalytic film. In the lower row, part of the cell envelope is magnified [19,20]. LE PHUC QUY AND VU THI HANH THU 91 Under UVA light irradiation (λ ≤ 385 nm), TiO2 generate the electron - hole pairs, electrons promoted from the valence band to the conduction band, thus forming an electron–hole pair, that move to the surface. The holes and electrons react with water molecules and oxygen attached to TiO2 surfaces forming hydroxyl radicals (OH) and superoxide anions (O− 2 ). These are highly reactive for both the oxidation of organic substances and the inactivation of bacteria and viruses [19]. .
