Development of photocatalytically active TiO2 thin films on expanded polystyrene foam using magnetron sputtering

Photoactive anatase TiO2 films were deposited on thermally sensitive expanded polystyrene (EPS) surface using reactive pulsed DC magnetron sputtering technique. Free-surface energy of EPS was increased by plasma treatment. Thickness of deposited TiO2 film was approximately 450 nm. Photocatalytic properties were investigated by bleaching methylene blue (MB) aqueous solution under UV-B, UV-A and daylight irradiation. TiO2 films deposited on EPS surface demonstrated significant photocatalytic effect under all three types of irradiation. Photocatalyst stability tests showed decrease of photocatalytic activity after each consecutive cycle (≈80% decrease after 5 cycles) due to detachment of unstable areas of TiO2 film and aggregation of MB solution at boundaries of closely connected EPS beads. The detailed analysis of TiO2 films was performed using combination of conventional SEM, XRD, XPS and other techniques.