Au-TiO₂ nanofilms for enhanced photocatalytic activity

Au/TiO₂ nanofilms are prepared on indium-tin oxide glass using magnetron sputtering. The bilayer nanofilms are heat-treated at 500 °C in air for 2 h. The microstructure evolution of the prepared Au/TiO₂ nanofilms is characterized, using scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction. The heat treatment leads to the migration of Au atoms to form Au/TiO₂ nanofilms with TiO₂ being in anatase phase and the presence of Au films/islands on the surface of the Au/TiO₂ nanofilms. The photocatalytic activity of the prepared Au/TiO₂ nanofilms in an aqueous solution of methylene blue (MB) is evaluated under the irradiation of visible light. The experimental results show that the photocatalytic activity of the prepared Au/TiO₂ nanofilms depends on the loading amount of Au. The rate constant for the photodegradation of the MB compound in the aqueous solutions with pure TiO₂ nanofilms is less than those with the prepared Au/TiO₂ nanofilms. Such behavior can be likely attributed to the activation of the photo-generated charge carriers and the increase of the electron–hole separation efficiency through localized surface plasmon resonance.