Selective Exposure of Robust Perovskite Layer of Aurivillius-Type Compounds for Stable Photocatalytic Overall Water Splitting.

Aurivillius-type compounds ((Bi 2 O 2 ) 2+ (A n -1 B n O 3 n +1 ) 2- ) with alternately stacked layers of bismuth oxide (Bi 2 O 2 ) 2+ and perovskite (A n -1 B n O 3 n +1 ) 2- are promising photocatalysts for overall water splitting due to their suitable band structures and adjustable layered characteristics. However, the self-reduction of Bi 3+ at the top (Bi 2 O 2 ) 2+ layers induced by photogenerated electrons during photocatalytic processes causes inactivation of the compounds as photocatalysts. Here, using Bi 3 TiNbO 9 as a model photocatalyst, its surface termination is modulated by acid etching, which well suppresses the self-corrosion phenomenon. A combination of comprehensive experimental investigations together with theoretical calculations reveals the transition of the material surface from the self-reduction-sensitive (Bi 2 O 2 ) 2+ layer to the robust (BiTiNbO 7 ) 2- perovskite layer, enabling effective electron transfer through surface trapping and effective hole transfer through surface electric field, and also efficient transfer of the electrons to the cocatalyst for greatly enhanced photocatalytic overall water splitting. Moreover, this facile modification strategy can be readily extended to other Aurivillius compounds (e.g., SrBi 2 Nb 2 O 9 , Bi 4 Ti 3 O 12 , and SrBi 4 Ti 4 O 15 ) and therefore justify its usefulness in rationally tailoring surface structures of layered photocatalysts for high photocatalytic overall water-splitting activity and stability.