Effects of crystal structure on photolysis of H2O on K-Ta mixed oxide

K-Ta mixed oxides with two different crystal structures, i.e. KTaO3 and K2Ta2O6, have been prepared by alkoxide and solid-state reaction routes. K2Ta2O6 single phase with pyrocrhore like structure can be obtained by the alkoxide method, however, this phase cannot be obtained by a conventional solid-state reaction route. It was found that the prepared K2Ta2O6 exhibits the higher activity to photolytic splitting of H2O into H-2 than that of KTaO3 which is reported as the active catalyst for the H2O decomposition. Crystalline size of K2Ta2O6 pseudo-pyrochlore oxide can be controlled by the hydrolysis condition for alkoxide. It was seen that the crystalline size has a large influence on the photocatalytic decomposition activity and the highest activity was obtained at the crystal size of 30 nm. Effects of metal loading were also investigated on K2Ta2O6 oxide and among the examined metals, activity to photolysis of water increased by loading Rh. Formation of oxygen was also observed when 0.2 wt.% Rh was loaded. (C) 2004 Elsevier B.V. All rights reserved.