Comparison of Photoelectrode Properties Between TiO[sub 2] Thin Films Doped with Tantalum and Dispersed with Nanosize Gold

Abstract

Ta-doped TiO 2 and Au/TiO 2 nanocomposite thin films were successfully synthesized by co-sputtering. The Ta-doped TiO 2 films formed a solid solution that induced structural changes from rutile to anatase phases. In the Au/TiO 2 nanocomposite films, Au particles with a diameter of about 15 nm were homogeneously distributed in the TiO 2 matrix. The anodic photocurrents of the Ta-doped TiO 2 electrodes and Au/TiO 2 nanocomposite electrodes were observed not only in the UV but also in the visible light range. The photoresponse in visible light between Ta-doped TiO 2 and Au/TiO 2 nanocomposite are due to bandgap reduction and photoexcitation of electrons from the interface states.