Synthesis of Three-Layer Perovskite Oxynitride KCaTaON·2HO and Photocatalytic Activity for H Evolution under Visible Light.

Substitution of oxide anions (O) in a metal oxide for nitrogen (N) results in reduction of the band gap, which is attractive in heterogeneous photocatalysis; however, only a handful of two-dimensional layered perovskite oxynitrides have been reported, and thus, the structural effects of layered oxynitrides on photocatalytic activity have not been sufficiently examined. This study reports the synthesis of a Ruddlesden-Popper phase three-layer oxynitride perovskite of KCaTaON·2HO, and the photocatalytic activity is compared with an analogous two-layer perovskite, KLaTaON·1.6HO.

An Artificial Z-Scheme Constructed from Dye-Sensitized Metal Oxide Nanosheets for Visible Light-Driven Overall Water Splitting.

Sensitization of a wide-gap oxide semiconductor with a visible-light-absorbing dye has been studied for decades as a means of producing H from water. However, efficient overall water splitting using a dye-sensitized oxide photocatalyst has remained an unmet challenge. Here we demonstrate visible-light-driven overall water splitting into H and O using HCaNbO nanosheets sensitized by a Ru(II) tris-diimine type photosensitizer, in combination with a WO-based water oxidation photocatalyst and a triiodide/iodide redox couple.