Influence of deposition atmosphere on photocatalytic activity of TiO2/SiOx double-layers prepared by RF magnetron sputtering

TiO2/SiOx double-layers have been prepared at room temperature by RF magnetron sputtering. The TiO2 top-layer was deposited in an Ar atmosphere, while the SiOx bottom-layer was deposited in an Ar/O2 atmosphere. Samples were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, and photoluminescence techniques. The photocatalytic activity of the samples was evaluated by the photodegradation of methylene blue; the results showed that the photocatalytic activity of the TiO2/SiOx double-layers was superior to that of the TiO2 single-layers. The presence of the SiOx bottom-layer improved the photocatalytic activity of the TiO2 layer because it may act as a trap for electrons generated in the TiO2 layer thus preventing electron-hole recombinations.