Constructing Halide Perovskite Heterojunction With Coherent Interface for Enhanced Photocatalytic Hydrogen Evolution

ABSTRACT Heterojunction engineering has been demonstrated to be effective in promoting charge separation and transfer in photocatalytic hydrogen (H 2 ) evolution reaction. To construct efficient heterojunction photocatalysts, band alignment between different photocatalysts has been primarily considered, whereas the importance of the lattice match at the heterointerface has been generally neglected. Herein, we presented the construction of a CH 3 NH 3 PbI 3 ‐(CH 3 NH 3 ) 3 Sb 2 I 9 (MAPbI 3 ‐MA 3 Sb 2 I 9 , MPI‐MSI) organic–inorganic hybrid perovskites (OIHPs) heterojunction with a coherent interface for efficient photocatalytic H 2 evolution reaction. Theoretical and experimental investigations indicate that the (101) plane of MAPbI 3 (MPI) and the (001) plane of MA 3 Sb 2 I 9 (MSI) exhibit small lattice mismatch, thus allowing the formation of a coherent interface with low interfacial defects and achieving efficient interfacial charge transfer. Moreover, band structure analysis indicates that the charge transfer at the MPI‐MSI heterointerface follows an ohmic‐like type‐I heterojunction mechanism, which allows the efficient separation and migration of the photogenerated charges. Consequently, the MPI‐MSI exhibits drastically enhanced photocatalytic activity, which is ca. 65.2 times that of MAPbI 3 and 471 times that of MA 3 Sb 2 I 9 . Moreover, by depositing Pt co‐catalyst, Pt/MPI‐MSI exhibits a superior photocatalytic H 2 evolution activity of ca. 377 μmol h −1 , representing the highest value reported for OIHPs‐based heterojunction photocatalysts.