Two‐Dimensional Perovskite Oxynitride K<sub>2</sub>LaTa<sub>2</sub>O<sub>6</sub>N with an H<sup>+</sup>/K<sup>+</sup> Exchangeability in Aqueous Solution Forming a Stable Photocatalyst for Visible‐Light H<sub>2</sub> Evolution
Takayoshi Oshima, Tom Ichibha, Kenji Oqmhula, Keisuke Hibino, Hiroto Mogi, Shunsuke Yamashita, Kotaro Fujii, Yugo Miseki, Kenta Hongo, Daling Lu, Ryo Maezono, Kazuhiro Sayama, Masatomo Yashima, Koji Kimoto, Hideki Kato, Masato Kakihana, Hiroshi Kageyama, Kazuhiko Maeda
Abstract
Abstract Undoped layered oxynitrides have not been considered as promising H 2 ‐evolution photocatalysts because of the low chemical stability of oxynitrides in aqueous solution. Here, we demonstrate the synthesis of a new layered perovskite oxynitride, K 2 LaTa 2 O 6 N, as an exceptional example of a water‐tolerant photocatalyst for H 2 evolution under visible light. The material underwent in‐situ H + /K + exchange in aqueous solution while keeping its visible‐light‐absorption capability. Protonated K 2 LaTa 2 O 6 N, modified with an Ir cocatalyst, exhibited excellent catalytic activity toward H 2 evolution in the presence of I − as an electron donor and under visible light; the activity was six times higher than Pt/ZrO 2 /TaON, one of the best‐performing oxynitride photocatalysts for H 2 evolution. Overall water splitting was also achieved using the Ir‐loaded, protonated K 2 LaTa 2 O 6 N in combination with Cs‐modified Pt/WO 3 as an O 2 evolution photocatalyst in the presence of an I 3 − /I − shuttle redox couple.