Conventional separation technologies to separate valuable commodities are energy intensive, consuming 15% of the worldwide energy. Mixed-matrix membranes, combining processable polymers and selective adsorbents, offer the potential to deploy adsorbent distinct separation properties into processable matrix. We report the rational design and construction of a highly efficient, mixed-matrix metal-organic framework membrane based on three interlocked criteria: (i) a fluorinated metal-organic framework, AlFFIVE-1-Ni, as a molecular sieve adsorbent that selectively enhances hydrogen sulfide and carbon dioxide diffusion while excluding methane; (ii) tailoring crystal morphology into nanosheets with maximally exposed (001) facets; and (iii) in-plane alignment of (001) nanosheets in polymer matrix and attainment of [001]-oriented membrane. The membrane demonstrated exceptionally high hydrogen sulfide and carbon dioxide separation from natural gas under practical working conditions. This approach offers great potential to translate other key adsorbents into processable matrix.

We report an in situ polymerization strategy to incorporate a thermo‐responsive polymer, poly(N‐isopropylacrylamide) (PNIPAM), with controlled loadings into the cavity of a mesoporous metal–organic framework (MOF), MIL‐101(Cr). The resulting MOF/polymer composites exhibit an unprecedented temperature‐triggered water capture and release behavior originating from the thermo‐responsive phase transition of the PNIPAM component. This result sheds light on the development of stimuli‐responsive porous adsorbent materials for water capture and heat transfer applications under relatively mild operating conditions.

A hydrolytically stable metal-organic framework (MOF) material, named KAUST-7', was derived from a structural phase change of KAUST-7 upon exposure to conditions akin to protonic conduction (363 K/95% relative humidity). KAUST 7' exhibited a superprotonic conductivity as evidenced by the impedance spectroscopic measurement revealing an exceptional conductivity up to 2.0 × 10 S cm at 363 K and under 95% RH, a performance maintained over 7 days. Ab initio molecular dynamics simulations suggested that the water-mediated proton transport mechanism is governed by water assisted reorganization of the H-bond network involving the fluorine moieties in KAUST-7' and the guest water molecules. The notable level of performances combined with a very good hydrolytic stability positions KAUST-7' as a prospective proton-exchange membrane alternative to the commercial benchmark Nafion. Furthermore, the remarkable RH sensitivity of KAUST-7' conductivity, substantially higher than previously reported MOFs, offers great opportunities for deployment as a humidity sensor.

Mg-CUK-1 exhibited high chemical stability towards H2S and H2O. Monte Carlo Simulations correlated with H2S uptake.

The development of new water adsorbents that are hydrothermally stable and can operate more efficiently than existing materials is essential for the advancement of water adsorption-driven chillers. Most of the existing benchmark materials and related systems in this field suffer from clear limitations that must be overcome to meet global requirements for sustainable and green energy production and utilization. Here, we report the energy-efficient water sorption properties of three isostructural metal-organic frameworks (MOFs) based on the simple ligand pyridine-2,4-dicarboxylate, named M-CUK-1 [M3(3-OH)2(2,4-pdc)2] (where M = Co 2+ , Ni 2+ or Mg 2+). The highly hydrothermally-stable CUK-1 series feature step-like water adsorption isotherms, relatively high H2O sorption capacities between P/P0 = 0.10-0.25, stable cycling, facile regeneration, and most importantly, benchmark coefficient of performance (COP) values for cooling and heating at low driving temperature. Furthermore, these MOFs are prepared under green hydrothermal conditions in aqueous solutions. Our joint experimental-computational approach revealed that M-CUK-1 integrates several optimal features, resulting in promising materials as advanced water adsorbents for adsorption-driven cooling and heating applications.

Adsorption-based heat transfer (AHT) devices are promising alternatives for green energy production and (re)­usage; however, they are still limited by the low performance of their benchmark adsorbent materials. Metal–organic frameworks (MOFs) have been ranked among the most promising water adsorbents for this application owing to their potential superior water uptake and moderate hydrophilicity. However, there is still a need to rationalize and understand at the microscopic scale the water adsorption performances of this family of materials to further guide the selection of the next-generation water adsorbents. In this context, a full understanding of the water adsorption mechanism in the most promising MOFs containing coordinated unsaturated sites is still highly challenging. Here, we explore the water adsorption in the mesoporous MOF MIL-100­(Fe) containing coordinated unsaturated Fe­(III) sites by combining advanced modeling and experimental tools. As a first stage, density functional theory calculations are performed to derive an accurate force field to describe the specific interactions between water and the coordinated unsaturated Fe­(III) sites. This force field is further implemented in a grand canonical Monte Carlo scheme to simulate the water adsorption isotherm and enthalpy in the whole range of relative pressures. A validation of the microscopic models and force field parameters is gained from a very good agreement between the experimental and simulated water adsorption data. As a further step, we provide an unprecedented description of the water adsorption microscopic mechanism in this very promising AHT water adsorbent by a careful analysis of the MIL-100­(Fe)/H2O interactions at low and intermediate relative pressures as well as the hydrogen bond network and cluster formation at higher relative pressure.

An unprecedented reversible guest-induced metallinker bond rearrangement in metal−organic framework (MOFs) was revealed by quantum-calculations and DRIFT experiments. As a showcase, the prototypical MOF-type MFM-300(Sc) was demonstrated to undergo a substantial Sc-carboxylate bond dynamics upon ammonia adsorption to enable a strong metal− guest binding mode, a key feature to ensure a highly efficient capture of this toxic molecule. Decisively, we evidenced this adsorption mechanism to be fully reversible, preserving the ammonia capture performance and structure integrity over multiple cycles. Such an unconventional mechanism in MOFs can open up new avenues to design novel materials for an efficient capture of highly corrosive molecules.

Incorporation of defects in metal-organic frameworks (MOFs) offers new opportunities for manipulating their microporosity and functionalities. The so-called "defect engineering" has great potential to tailor the mass transport properties in MOF/polymer mixed matrix membranes (MMMs) for challenging separation applications, for example, CO 2 capture. This study first investigates the impact of MOF defects on the membrane properties of the resultant MOF/polymer MMMs for CO 2 separation. Highly porous defect-engineered UiO-66 nanoparticles are successfully synthesized and incorporated into a CO 2 -philic crosslinked poly(ethylene glycol) diacrylate (PEGDA) matrix. A thorough joint experimental/simulation characterization reveals that defect-engineered UiO-66/PEGDA MMMs exhibit nearly identical filler-matrix interfacial properties regardless of the defect concentrations of their parental UiO-66 filler. In addition, nonequilibrium molecular dynamics simulations in tandem with gas transport studies disclose that the defects in MOFs provide the MMMs with ultrafast transport pathways mainly governed by diffusivity selectivity. Ultimately, MMMs containing the most defective UiO-66 show the most enhanced CO 2 /N 2 separation performance-CO 2 permeability = 470 Barrer (four times higher than pure PEGDA) and maintains CO 2 /N 2 selectivity = 41-which overcomes the trade-off limitation in pure polymers. The results emphasize that defect engineering in MOFs would mark a new milestone for the future development of optimized MMMs.