Photocatalytic water splitting on hydrated layered perovskite tantalate A(2)SrTa(2)O(7)center dot nH(2)O ( A = H, K, and Rb)

A series of layered perovskite tantalates, A(2)SrTa(2)O(7) (A=H, Li, K, and Rb), were prepared as novel photocatalysts for photocatalytic water splitting into H-2 and O-2 under UV irradiation. The layered perovskite tantalates with hydrated interlayer space, A(2)SrTa(2)O(7).nH(2)O (A=H, K, and Rb), showed higher H-2 formation rate than anhydrous layered tantalate, Li2SrTa2O7, and anhydrous perovskite tantalate, KTaO3. H2SrTa2O7.nH(2)O and K2SrTa2O7.nH(2)O showed high activity for overall splitting of water without loading co-catalysts. The reaction over H2SrTa2O7.nH(2)O proceeded steadily more than 70 h, demonstrating a high durability of the catalyst. Effects of hydrated interlayer space on the catalytic activity were discussed on the basis of the results of photoluminescence spectra and the hydrogen evolution from aqueous solution of n-butylamine as a test reaction. The results indicate that the availability of interlayer space of layered tantalate as reaction sites is an important factor to improve the photocatalytic activity of Ta-based semiconductor materials.