Study of the effect of a silver nanoparticle seeding layer on the crystallisation temperature, photoinduced hydrophylic and catalytic properties of TiO 2 thin films deposited on glass by magnetron sputtering

The optimization of the photocatalytic activity and hydrophilic conversion of TiO 2 is an active research area in the field of self-cleaning materials and energy storage/conversion. One major focus is the crystalline phase of TiO 2, known to be the most efficient of the anatase structures. Another issue is the decoration of TiO 2 with noble metals, which act as charge carrier traps for electrons. The latter hinders or reduces the electron-hole recombination rate and often leads to a more efficient photocatalytic activity. In this paper, we describe how an interlayer consisting of 3-4nm silver nanoparticles (Ag-NPs) promotes TiO 2 anatase crystallisation and has a positive effect on the photoinduced catalytic and hydrophylic properties of TiO 2 thin films. Ag-NPs and TiO 2 were deposited by magnetron sputtering in the same reactor in a two-step process: a) condensation of Ag-NPs produced in the gas phase thanks to a high-pressure discharge, and b) conventional TiO 2 magnetron deposition in oxide mode. Four temperatures from RT to 288°C were investigated and film thickness was 80nm. Particle size and film structure were determined by TEM, HRTEM and XRD. Photocatalytic activities of the samples were tracked by the evaluation of the surface hydrophilicity after UV illumination and 24. hours post-illumination, and by UV-induced palmitic acid degradation. © 2011.