A series of Ruddlesden-Popper-type hydrous layered perovskites, A′ 2 ATa 2 O 7 (A′ ) H or K, A ) La 2/3 or Sr), were presented as novel catalysts for photocatalytic water splitting into H 2 and O 2 under UV irradiation. These hydrous perovskites showed higher activity than anhydrous perovskites (KTaO 3 , La 1/3 TaO 3 ) for overall splitting of water. Results of photoluminescence spectroscopy and H 2 evolution from aqueous n-butylamine solution support the hypothesis that the high activity of the hydrous perovskites results from their hydrated layered structure, where the photogenerated electrons and holes can be effectively transferred to the intercalated substrates (H 2 O and n-butylamine). Addition of Ni cocatalyst to H 2 La 2/3 Ta 2 O 7 via an ion-exchange reaction increased the activity, while Ni addition did not improve the activity of H 2 SrTa 2 O 7 . Ni K-edge EXAFS/XANES, UV-vis spectroscopy, and TEM results for Niloaded catalysts indicate that Ni 2+ ions and small NiO clusters are intercalated into the layers of H 2 La 2/3 Ta 2 O 7 , while relatively large NiO particles at the external surface of the perovskite are the main Ni species in H 2 SrTa 2 O 7 . Thus, the highly dispersed Ni(II) species at the interlayer space are shown to act as effective sites for H 2 evolution in the photocatalytic water splitting.

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Catalysts H 2000Photocatalytic Water Splitting on Ni-Intercalated Ruddlesden-Popper Tantalate H2La2/3Ta2O7. -The title compound shows higher photocatalytic activity for water splitting into H2 and O2 under UV irradiation than anhydrous perovskites. Intercalation of Ni 2+ cations and NiO clusters into the perovskite layers of the title compound improves the activity. The high activity could be due to a short-distance migration of photogenerated electrons and holes to the adjacent Ni(II) and surface TaO 6 sites, resp., and a resulting separation of the electron and hole pairs. This is the first example of highly active metal-intercalated layered tantalate photocatalysts with hydrated interlayer space. -(SHIMIZU*, K.-I.; ITOH, S.; HATAMACHI, T.; KODAMA, T.; SATO, M.; TODA, K.; Chem.