Reduction on specific lattice planes for metal–organic frameworks/poly-pyrrole composites with dilated porosity

Abstract

Owing to the microporosity, metal–organic frameworks (MOFs) have attracted great attention in various applications, whereas their potential for mass transfer and diffusion of larger molecules has been limited. To break the limit of circumscribed microporosity and gain more applications, it is necessary to dilate the original limited pore size in the MOF structure. Despite many attempts, the generation of orderly distributed porosity in pristine MOFs with precise modulation on the molecular level remains a challenge. In this paper, we present an orientation–modification strategy realized by a plane-oriented etchant of pyrrole (Py), which reduces metal sites into a low-cation valence on specific lattice planes and induces missing linker defects in MOFs. The density functional theory pore size distribution analysis demonstrates that the emerging micropore diameter of the resultant Cu-BTC/PPy is more than twice that of the original Cu-BTC. The coordination mode between Cu⁺/Cu²⁺ and linkers is proposed by various chemical characterizations. Moreover, it has been found that Cu-BTC/PPy performs much better in styrene oxidation performed not only in oil baths but also under simulated sunlight at room temperature owing to its enlarged porosity and photothermal effect. This work demonstrates an effective protocol for precisely regulating and modifying the properties of MOFs at the molecular scale for fabricating MOF/polymer composites.