Dual Organic-Inorganic Encapsulation and Ternary Heterojunction Engineering Toward Water-Resistant CsPbBr3 Perovskite Photocatalysts for Hydrogen Production.

Metal halide perovskites are promising photocatalysts for solar hydrogen production but suffer from severe water instability. Herein, a dual organic-inorganic encapsulation strategy is developed to construct water-resistant CsPbBr3 nanocrystals. Hydrophobic zwitterionic ligands, in combination with an epitaxial CsPb2Br5 shell, effectively isolate the CsPbBr3 core from water while maintaining structural integrity. To overcome the carrier-blocking effect induced by encapsulation, hollow CoSx is introduced to form a sandwich-like heterostructure, in which CsPbBr3 is spatially confined between CoSx and CsPb2Br5. This architecture enables directional charge transfer via a Schottky CoSx/CsPbBr3 interface for efficient electron extraction and a type-II CsPbBr3@CsPb2Br5 heterojunction for hole transport. Benefiting from the synergistic stabilization and charge-management effects, the resulting photocatalyst achieves a hydrogen evolution rate of 5.36 mmol h-1 g-1 with an apparent quantum efficiency of 4.19% at 420 nm, while maintaining stable performance over five cycles. This work provides a general strategy for integrating multi-layer encapsulation with carrier-selective interfaces to realize durable and efficient perovskite photocatalysts for aqueous hydrogen evolution.