Effects of crystal structure on photolysis of H 2O on K–Ta mixed oxide

Abstract

K–Ta mixed oxides with two different crystal structures, i.e. KTaO 3 and K 2Ta 2O 6, have been prepared by alkoxide and solid-state reaction routes. K 2Ta 2O 6 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 K 2Ta 2O 6 exhibits the higher activity to photolytic splitting of H 2O into H 2 than that of KTaO 3 which is reported as the active catalyst for the H 2O decomposition. Crystalline size of K 2Ta 2O 6 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 K 2Ta 2O 6 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.