Water-stable MAPbBr@PbBrOH QDs confined by metal-organic framework for photodegradation of wastewater.

While the metal halide perovskite materials are emerging as potentially promising photocatalysts, they still suffer from the intrinsic instability, seriously hampering their further practical applications. In this study, a perovskite-based composite with a sandwich structure is first established to realize the encapsulation of individual octylamine-capped MAPbBr (OM-PE) quantum dots (QDs), and the Zeolitic Imidazolate Framework-67 (ZIF-67) isolates the individual OM-PE@PbBrOH QDs (2 nm) to preserve their unique optoelectronic properties while preventing degradation from environmental factors. The resulting sandwich composite was proved to be a staggered-gap heterostructure with a p-n junction, in which the PbBrOH layer acted as a water-resisting covering and ZIF-67 layer promoted the electron mobility. Benefiting from the chemical interactions and interfacial charge dynamics among the different layers, the OM-PE@PbBrOH⊂ZIF-67 composite exhibited the superior stability in water for two months, and presented an enhanced photodegradation efficiency of organic dyes (malachite green, methylene blue and rhodamine B), which is around 24 times higher than that of pristine perovskite. By integrating the respective merits of each component, this work unprecedentedly constructs the 2 nm sandwich-like OM-PE@PbBrOH⊂ZIF-67 composite, and opens new avenues for stable, efficient, and multifunctional photocatalytic systems, with potential applications beyond wastewater treatment.