Photocatalytic Water Splitting on Hydrated Layered Perovskite Tantalate A2SrTa2O7×nH2O (A: H, K, and Rb).

A series of layered perovskite tantalates, A2SrTa2O7 (A=H, Li, K, and Rb), were prepared as novel photocatalysts for photocatalytic water splitting into H2 and O2 under UV irradiation. The layered perovskite tantalates with hydrated interlayer space, A2SrTa2O7·nH2O (A=H, K, and Rb), showed higher H2 formation rate than anhydrous layered tantalate, Li2SrTa2O7, and anhydrous perovskite tantalate, KTaO3. H2SrTa2O7·nH2O and K2SrTa2O7·nH2O showed high activity for overall splitting of water without loading co-catalysts. The reaction over H2SrTa2O7·nH2O 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.