Hierarchical Porous Zeolitic Imidazolate Frameworks: Microporous to Macroporous Regime

The creation of different pore size regimes into zeolitic imidazolate frameworks (ZIFs) to form hierarchical porous structures enhanced the material's performance for various applications. This book chapter focuses on the synthetic strategies for creating ZIFs with pore structures containing multiple pore regimes and provides readers with a broader scope of the strategies available for the fabrication of hierarchical porous ZIFs. Hierarchical porous ZIFs can be synthesized using in situ and ex situ synthesis procedures. Different synthesis procedures were reported, including template-based method, template-free procedure, and three-dimensional (3D) printing. The material's porosity can be characterized using nitrogen adsorption–desorption isotherms, mercury intrusion porosimetry, transmission electron microscopy, and scanning electron microscopy. Hierarchical porous ZIFs offered a complex porous structure. Thus, the combination of different techniques to characterize the material’s porosity is highly required. Overall, this chapter offered a roadmap that may guide the scientists and researchers to design and develop hierarchical porous ZIFs materials with different pore size regimes and high molecular precision.