Structure–property relationships of water adsorption in metal–organic frameworks

Abstract

Among porous solids, MOFs exhibit a wealth of water adsorption behaviors.

Hierarchical MOF-xerogel monolith composites from embedding MIL-100(Fe,Cr) and MIL-101(Cr) in resorcinol-formaldehyde xerogels for water adsorption applications

“…Various materials, predominately of the MIL (Materials of Institute Lavoisier) family, have been investigated for water adsorption [28,29] and also different strategies of tuning prototypical MOFs to enhance the water uptake have been examined [30,31]. Long term and cycle measurements have been performed to ensure the required water stability [32,33,34].…”

Characterization of adsorbed water in MIL-53(Al) by FTIR spectroscopy and ab-initio calculations

“…The results given by publications devoted to this point show that water adsorption mechanisms in MIL-53 have not been yet completely elucidated. 49,51,[53][54][55][56][57] From a general point of view, MIL-53 materials may be considered as hydrophobic materials because the enthalpy of water adsorption at zero loading is lower than the liquefaction enthalpy. 49 Water molecules are only physisorbed at the surface by hydrogen bonding interactions.…”

“…58,59 In addition, water adsorption induces a shrinkage of MIL-53(Al) framework 57 and even when water is physisorbed the adsorption and desorption process is not always reversible. A large hysteresis loop is observed on the adsorption-desorption isotherm for MIL-53(Al), 57 whereas water adsorption-desorption is reversible for gallium or chromium based MIL-53 materials. NMR, X-ray diffraction, and molecular simulations give some information about the location of water molecules inside the pores.…”

Screening of mixed-linker CAU-10 MOF materials for humidity sensing by impedance spectroscopy

“…High Henry constants are associated with low r values and vice versa. Hydrophilic modification leads to an increase in water adsorption affinity at low relative humidity values which in turn shifts pore filling to lower p/p 0 values [17]. This correlation is partly represented by the comparison of our sulfonic acid-modified samples with the unmodified samples [9,13].…”

“…However, even for microporous MOFs a small hysteresis may be observed, which is frequently attributed to a slight structural flexibility of the network [17]. Reinsch et al also stated that dehydration of the samples (at room temperature in vacuum) leads to minor structural changes [12].…”