Metal-organic frameworks (MOFs) and inorganic fillers are frequently incorporated into mixed-matrix membranes (MMMs) to overcome the traditional trade-off in permeability ( P) and selectivity for pure organic polymer membranes. Therefore, it is of great interest to examine the influence of porous and nonporous fillers in MMMs with respect to the possible role of the polymer-filler interface, that is, the void volume. In this work, we compare the same MOF filler in a porous and nonporous state, so that artifacts from a different polymer-filler interface are excluded. MMMs with the porous MOF aluminum fumarate (Al-fum) and with a nonporous dimethyl sulfoxide solvent-filled aluminum fumarate (Al-fum(DMSO)), both with Matrimid as polymer, were prepared. Filler contents ranged from 4 to 24 wt %. Gas separation performances of both MMMs were studied by mixed gas measurements using a binary mixture of CO/CH with gas permeation following the theoretical prediction by the Maxwell model for both porous and nonporous dispersed phase (filler). MMMs with the porous Al-fum filler showed increased CO and CH permeability with a moderate rise in selectivity upon increasing filler fraction. The MMMs with the nonporous Al-fum(DMSO) filler displayed a reduction in permeability while maintaining the selectivity of the neat polymer. A linear dependence of log P versus the reciprocal specific free fractional volume (sFFV) rules out a significant contribution from a void volume. The sFFV includes the free volume of the polymer and the MOF, but not the polymer-filler interface volume (so-called void volume). The sFFV for the MMM was calculated between 0.23 cm/g for a 24 wt % Al-fum/Matrimid MMM and 0.12 cm/g for a 24 wt % Al-fum(DMSO)/Matrimid MMM. The negligible effect of an interface volume is supported by a good matching of theoretical and experimental density of the Al-fum and Al-fum/(DMSO) MMMs which gave a specific void volume below 0.02 cm/g, often even below 0.01 cm/g.

Covalent triazine frameworks (CTFs) are little investigated, albeit they are promising candidates for electrocatalysis, especially for the oxygen evolution reaction (OER). In this work, nickel nanoparticles (from Ni(COD)2) were supported on CTF-1 materials, which were synthesized from 1,4-dicyanobenzene at 400 °C and 600 °C by the ionothermal method. CTF-1-600 and Ni/CTF-1-600 show high catalytic activity towards OER and a clear activity for the electrochemical oxygen reduction reaction (ORR). Ni/CTF-1-600 requires 374 mV overpotential in OER to reach 10 mA/cm2, which outperforms the benchmark RuO2 catalyst, which requires 403 mV under the same conditions. Ni/CTF-1-600 displays an OER catalytic activity comparable with many nickel-based electrocatalysts and is a potential candidate for OER. The same Ni/CTF-1-600 material shows a half-wave potential of 0.775 V for ORR, which is slightly lower than that of commercial Pt/C (0.890 V). Additionally, after accelerated durability tests of 2000 cycles, the material showed only a slight decrease in activity towards both OER and ORR, demonstrating its superior stability.

A metal–organic gel (metallogel) based on the new tetracarboxyl ligand N 1,N 4-(diterephthalic acid)­terephthalamide in combination with chromium­(III) has been converted into its xero- and aerogel and demonstrated to have excellent specific sorption properties for dyes in its metallogel state, where fuchsine is adsorbed faster than the two other dyes, calcein and disulfine blue, and for water, sulfur dioxide and carbon dioxide in its xero- and aerogel state. The metallogel showed very good shape retention and could be extruded from molds in designed shapes. In a rheology experiment, the storage modulus was determined to be 1440 Pa, and the metallogel is elastic up to 3 Hz, breaking at strains higher than 0.3%. Additional metallogels utilizing the same ligand with a wide range of metal ions (Al­(III), Fe­(III), Co­(III), In­(III), and Hg­(II)) have also been synthesized, and the aluminum and mixed aluminum–chromium derivative were also converted into its aerogel. The highly porous Cr, Al, and AlCr metal–organic aerogels proved stable against water vapor in a physisorption experiment and were used to model breakthrough curves for SO2/CO2 gas mixtures with the idealized adsorbed solution theory from their physisorption isotherms. The breakthrough simulation utilized SO2/CO2 equivalencies from a real world application and showed effective retention of SO2 from the gas mixture. Furthermore, the materials in this work exhibit the highest SO2 uptake values for metal–organic aerogels so far (up to 116.8 cm3 g–1, or 23.4 wt %).

Long-term monitoring for storage/transport and improved handling of luminescent MOF sensors is achieved using MMM fabrication for humidity sensing.