Thin film TiO2 photocatalyst deposited by reactive magnetron sputtering

Abstract TiO 2 films were deposited by r.f. reactive magnetron sputtering on non-alkali glass at 200 °C under total gas pressure of 0.3, 1.0 and 3.0 Pa with oxygen flow ratio [O 2 /(O 2 +Ar)] of 30%. All films showed polycrystalline anatase structure, in which a small portion of rutile phase was observed only for the films deposited at 0.3 Pa. The films deposited at total gas pressure ( p tot ) of 3.0 Pa performed photoinduced hydrophilicity and high photocatalytic activities, i.e. photoinduced decomposition of acetaldehyde (CH 3 CHO) gas and adsorbed Methylene Blue on the film surface. The photocatalytic activity of the films showed the clear tendency to decrease with the decrease in p tot during the deposition. Such degradation of the photocatalytic activity was considered to be correlated with the transport processes of the high-energy particles in the sputter deposition processes. In the case of the lower p tot of 0.3 or 1.0 Pa, the films showed poor photocatalytic activities because of the defect level generations caused by the bombardment of the high-energy particles on the growing film surface. Such defect levels should be the recombination centers of the electron–hole pairs induced by the UV illumination and decrease their lifetime.