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.

A hydrolytically stable 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 x 10-2 S.cm-1 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 pending 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.

Proton conducting materials are key components in proton exchange membrane fuel cells for clean energy research. Most such conducting crystalline materials (MOFs/CPs/COFs/HOFs) show limited practical application due to the multistep synthesis of organic ligands and usage of hazardous solvents. To look for simple and highly efficient crystalline proton conducting materials, we present herein a coordination polymer, PCM-1, based on a positively charged [Co(bpy)₄(H₂O)₂]²⁺ (bpy = 4,4′-bipyridine) backbone. The presence of a cationic unit, anionic nitrates, as well as coordinated and adsorbed water molecules is demonstrated to play a significant role in the water-assisted ultrahigh superprotonic conduction properties. PCM-1 displays a conductivity value of over 10⁻² S cm⁻¹ at 98% relative humidity (RH) and 80 °C without any loss of performance over multiple cycles, ranking among the most promising proton conducting materials in the domain of MOFs/CPs/COFs/HOFs. Quasi-elastic neutron scattering (QENS) and molecular simulations were further combined to gain a better understanding of these properties at the molecular level. This joint experimental/modeling study revealed water-assisted proton dynamics through the formation of a long-range H-bonded network mediated by a Teixeira jump diffusion model. Furthermore, this material was shown to be highly stable and easily scalable using a green and simple synthesis process.