Constructing strategies for hierarchically porous MOFs with different pore sizes and applications in adsorption and catalysis

Since metal-organic frameworks, a versatile class of crystalline organic-inorganic hybrid materials featuring well-aligned intrinsic porosity, have come of age, the research focus has shifted from structural considerations toward the many fascinating properties enshrined in their real industrial applications. However, most MOFs reported to date only have microporous structures, which restrict mass transfer and inhibit macromolecules from accessing their pores. Hierarchically porous MOFs have been proposed because mesopores or macropores can alleviate these challenges. The strategies used to construct hierarchically porous MOFs have been discussed in this review article based on the pore size typically generated by each method and several instances of their applications in adsorption diffusion are shown. These applications demonstrate that the mass transport rate of hierarchically porous MOFs is improved when compared to pristine microporous MOFs, which is expected to solve the key problems found in application fields such as adsorption, catalysis, and sensing. Finally, the properties and challenges of hierarchically porous MOFs have been summarized, along with some recommendations for their future development.