Photocatalytic water splitting on hydrated layered perovskite tantalate A2SrTa2O7·nH2O (A = H, K, and Rb)

Abstract

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.