Photoelectrochemical properties of mixed oxides. Mixed oxides of titanium and rare earths

To select anode material for photoelectrochemical water decomposition and also to study the model of mixed oxide zone diagram applicability a series of rare earth titanates: La2Ti2O7, La2TiO5, Nd2Ti2O7, Eu2Ti2O7, Sm2Ti2O7, Gd2Ti2O7, Dy2Ti2O7, Er2Ti2O7, Yb2Ti2O7 and Lu2Ti2O7 is investigated. On electrodes made of these materials anodic photocurrent is observed in aqueous solution. Potentials of these compound flat bands that are smaller by a factor of 0.5-1.0 V than hydrogen electrode potential in the same solution are found as well as the wave length of the light exciting photocurrent that is less than 400 nm. The results obtained are explained basing on the representation on interstitial filled band located above the ceiling of TiO2 valence band. In lanthanum and neodymium titanate photocurrent spectrum peaks are detected with the wave length being about 450 nm, in samarium titanate - 450 and 675 nm, in europium titanate - 450 and 550 nm