Recent Advances in Hierarchical Porous Engineering of MOFs and Their Derived Materials for Catalytic and Battery: Methods and Application

Abstract

Hierarchical porous materials have attracted the attention of researchers due to their enormous specific surface area, maximized active site utilization efficiency, and unique structure and properties. In this context, metal–organic frameworks (MOFs) offer a unique mix of properties that make them particularly appealing as tunable porous substrates containing highly active sites. This review focuses on recent advances in the types and synthetic strategies of hierarchical porous MOFs and their derived materials. Furthermore, it highlights the relationship between the mass diffusion and transport of hierarchical porous structures and the pore size with examples and simulations, while identifying their potential and limitations. On this basis, how the synthesis conditions affect the structure and electrochemical properties of MOFs based hierarchical porous materials with different structures is discussed, highlighting the prospects and challenges for the synthetization, as well as further scientific research and practical applications. Finally, some insights into current research and future design ideas for advanced MOFs based hierarchical porous materials are presented.

Enhanced Catalytic Activity through the Variation of Hierarchical Porosity in a Zr-Based Metal–Organic Framework

“…The ability to tune the microporosity and chemical properties in the MOFs through the modulation of metal ions or their cluster-based nodes, along with the organic linker functionalities, has made them very attractive in several interesting applications. Such a synergic contribution of both the space/porosity and the chemical functionalities in MOFs has led to the occurrence of some interesting properties and the realization of a set of very relevant material applications, including storage and separation of molecules and charge, sensing, and catalysis. − In particular, the family of MOFs, with the 12/8/6-connecting metal-oxo cluster nodes (M = Ti, Zr, Hf, Th, Ce, and other rare-earth metals) and di/tri/tetratopic linkers with an interesting spectrum of functional groups, has been explored well, for their functional properties, due to the chemical and thermal stabilities. − In general, the tunable porosity and functional properties in the UiO family of MOFs have been accessed through the variations in the linker and nodes, through the variation of size, length, topology, and chemical functionality, including via some attractive post-synthetic modification strategies. − Coordination modulator-based defect-engineering techniques have also been utilized as a tool to tune the pore characteristics but, in most such cases, are limited within the microporous domain. − To enhance the accessibility to the deeply buried functional sites and overcome the mass-transfer limitations in most of the MOFs, which are intrinsically microporous, further strategies to introduce the mesopores and macropores, and achieving a hierarchical interconnectedness through all the three pore-size domains of the nanoporous materials are of great necessity. − Such methods can be well-summarized and classified as being based on either bottom-up or top-down approaches. The techniques can also be understood as chemical and physical methods. − In the literature, there have been several examples of hierarchically porous (HP) UiO-MOFs, prepared by physical methods: some of them fall under top-down approaches and/or post-synthetic modifications (see Table S1 in the Supporting Information). − There have also been several examples of the bottom-up methods, including the ones that are template-based synthesis.…”