Remarkable improvement of visible light photocatalytic activity of TiO2 nanotubes doped sequentially with noble metals for removing of organic and microbial pollutants

Abstract

The aim of this study was to show that Ag and Au nanoparticles (NPs) can have a synergistic effect on the photocatalytic and antibacterial activity of TiO2 nanotubes (NTs) under visible irradiation. TiO2 NTs were grown on Ti substrate by anodic oxidation and modified with Ag and Au NPs by dip coating and sputtering methods, respectively. The spherical 5–20nm Ag and Au NPs were deposited on TiO2 NTs with diameter of 50–80nm. In contrast to obtained results under UV irradiation, visible-light absorption range and visible photocatalytic activity of Ag and Au co-modified TiO2 NTs were much higher than TiO2 NTs without modification and TiO2 NTs modified with monometallic NPs. Photocatalytic activity of modified TiO2 NTs increased with increasing annealing temperature and appearing rutile phase. Antibacterial activity of Ag and Au-comodified TiO2 NTs against E. coli was noticeably more than that of TiO2 NTs modified with monometallic NPs.