Evaluation of the Effect of Annealing Temperature on Photocatalytic Properties of TiO2 Nanotubes Modified with Gold and Silver metals

Abstract TiO2 nanotubes (NTs) have unique properties to use in photocatalytic systems. Recently improvement of photocatalytic activity of TiO2 NTs under visible light irradiation has attracted great attention. In this study, effect of annealing temperature (400-700C) on photocatalytic activity of TiO2 NTs modified with Ag and Au was evaluated. TiO2 NTs were synthesized via anodization method and then modified with Ag and Au nanoparticles (NPs) using dip coating and sputtering methods, respectively. SEM, HRTEM and EDX results confirmed presence of Ag and Au NPs on TiO2 NTs with diameter of 60 nm. Increasing the annealing temperature enhances visible light absorption range of nanocatalyst attributed to increase of rutile/anatas ratio and formation of different nanostructures of Ag and Au NPs. Catalytic efficiency of modified TiO2 was enhanced from 34% to 76% with increasing annealing temperature. Best catalytic efficiency was achieved by annealing TiO2 NTs at 500C.