Low-temperature formation of photocatalytic Pt-anatase film by magnetron sputtering

Films of TiO2 dispersed or coated with platinum were deposited on glass and Pt-buffered polyamide substrates respectively by magnetron sputtering. The photocatalytic activity of the films was evaluated through the decompositi on of acetic acid under UV irradiation. The Pt-dispersed TiO2 film of appro ximately 1.5 wt % platinum shows a maximum activity due to for the formatio n of anatase phase with a fine grain size. Platinum particles similar to 20 Angstrom in thickness coated on anatase film greatly improves activity. Th e activity shows a steplike dependence of film thickness where the critical thickness varies between 150 and 200 nm depending on the deposition temper atures. The correlation between defects and activity was verified by measur ing either the temperature dependence of electric resistance or the shift o f binding energy from XPS. (C) 1999 Kluwer Academic Publishers.