Characterization of Planar Defect in Layered Perovskite Photocatalyst Y<sub>2</sub>Ti<sub>2</sub>O<sub>5</sub>S<sub>2</sub> by Electron Microscopy and First-Principles Calculations
Mamiko Nakabayashi, Kazutaka Nishiguchi, Xizhuang Liang, Takashi Hisatomi, Tsuyoshi Takata, Takashi Tsuchimochi, Naoya Shibata, Kazunari Domen, Seiichiro Ten‐no
Abstract
Layered perovskite Y 2 Ti 2 O 5 S 2 is a promising semiconductor photocatalyst with an electronic structure suitable for overall water splitting under visible light. However, similar to other photocatalysts, structural defects during synthesis should be controlled. Transmission electron microscopy (TEM) revealed extremely large planar defects composed of S–Mg–S layers in Y 2 Ti 2 O 5 S 2 synthesized using the flux method. We determined the planar defect structure and electronic structure using first-principles calculations based on the density functional theory. The evaluation of the formation energy suggests that S- and Mg-poor conditions may prevent defect formation. Furthermore, we discuss the impurity levels caused by the planar defects and their effects on the electronic state and catalytic performance.