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Bismuth-based oxyhalides with layered Sillén(−Aurivillius) structures have attracted significant attention as photocatalysts. Recent studies have unveiled a part of the structure-property relationship of this material; however, it has not been...

Sillen–Aurivillius layered oxyhalides with single-, double- and triple-perovskite slabs (n = 1–3) are promising visible-light-driven photocatalysts for water splitting with different behaviors observed depending on n. However, there was no report on the photocatalytic activity of n ≥ 4 phases. Here, we report three new oxychlorides BaBi5Ti3O14Cl, Ba2Bi5Ti4O17Cl and Ba3Bi5Ti5O20Cl, respectively, with triple-, quadruple- and quintuple-perovskite layers. The synthesis of these phases involves a “bricklaying” synthesis, where a plain perovskite, BaTiO3, a Sillen phase, BaBiO2Cl, and Aurivillius phases Bi4Ti3O12, BaBi4Ti4O15, and Ba2Bi4Ti5O18 were used as building blocks. The present Sillen–Aurivillius oxychlorides have appropriate valence and conduction band levels for visible-light-induced water splitting. DFT calculation for BaBi5Ti3O14Cl (n = 3) and Ba3Bi5Ti5O20Cl (n = 5) indicates that their valence and conduction bands are separated spatially on the perovskite and fluorite layers, respectively. The photocatalytic activity of the three Sillen–Aurivillius oxychlorides is enhanced with increasing the number of the perovskite layers.

We show that oxyhalide Bi5PbTi3O14Cl is a potential photocatalyst for visible-light-induced water splitting owing to the appropriate band levels for both water reduction and oxidation. The present ...

A series of Sillen–Aurivillius layered oxyhalides with a single- and double-perovskite layer, Bi4MO8X (M = Nb, Ta; X = Cl, Br) and AA′Bi3M2O11Cl (A, A′ = Sr, Ba, Pb, Bi; M = Ti, Nb, Ta), have been recently demonstrated as promising photocatalysts for visible-light-induced water splitting due to relatively high energy valence bands arising from strong interactions between Bi-6s and O-2p orbitals. Herein, we report the synthesis, characterization and photocatalytic property of Bi5SrTi3O14Cl with triple-perovskite layers. The combined use of synchrotron X-ray diffraction and scanning transmission electron microscopy allowed the precise determination of the crystal structure (space group: P2an), including site occupancies. The experimental results revealed that Bi5SrTi3O14Cl possesses a similar bandgap and valence band level as the previously reported Bi5PbTi3O14Cl, indicating that the presence of Pb-6s is not essential for the formation of a higher energy valence band maximum. Partial density of states for both materials obtained by DFT calculations suggested considerable interactions of the Bi-6s orbitals with the O-2p orbitals, in particular those in the perovskite layers, which is the key to the formation of the higher energy valence band. Bi5SrTi3O14Cl exhibited higher activity for O2 evolution than Bi5PbTi3O14Cl, suggesting the detrimental effect of Pb2+ on the photocatalytic activity, thereby allowing the construction of a Z-scheme water splitting system workable under visible light.