Ultrapermeable Composite Membranes Enhanced Via Doping with Amorphous MOF Nanosheets

Abstract

Thin-film composite (TFC) polymeric membranes have attracted increasing interest to meet the demands of industrial gas separation. However, the development of high-performance TFC membranes within their current configuration faces two key challenges: (i) the thickness-dependent gas permeability of polymeric materials (mainly poly­(dimethylsiloxane) (PDMS)) and (ii) the geometric restriction effect due to the limited pore accessibility of the underlying porous substrate. Here we demonstrate that the incorporation of trace amounts (∼1.8 wt %) of amorphous metal–organic framework (MOF) nanosheets into the gutter layer of TFC assemblies can simultaneously address these two limitations by the creation of rapid, transmembrane gas diffusion pathways. The resultant PDMS&MOF membrane displayed excellent CO2 permeance of 10450 GPU and CO2/N2 selectivity of 9.1. Leveraging this strategy, we successfully fabricate a novel TFC membrane, consisting of a PDMS&MOF gutter and an ultrathin (∼54 nm) poly­(ethylene glycol) top selective layer via surface-initiated atom transfer radical polymerization. The complete TFC membrane exhibits excellent processability and remarkable CO2/N2 separation performance (1990 GPU with a CO2/N2 ideal selectivity of 39). This study reveals a strategy for the design and fabrication of a new TFC membrane system with unprecedented gas-separation performance.

Microwave Absorption Performance Evaluation of Carbonized Derivatives of Fe3O4@MOF-74 with Controllable Morphologies

“…To clarify the state of the main element, high-resolution XPS analysis was carried out. The high-resolution C 1s XPS spectra are shown in Figure B, and the corresponding peaks at 288.8, 286.4, and 284.8 eV were assigned to C–O, C–C, and CC . High-resolution XPS spectra (Figure C) showed two characteristic peaks at 724.8 and 711.5 eV assigned to Fe 2p 1/2 and Fe 2p 2/3 , which correspond to the coordination metal Fe 3+ .…”

Mechanistic Principles for Engineering Hierarchical Porous Metal–Organic Frameworks

“…The triangular type H2 hysteresis loop displays a steep desorption branch. This has been frequently attributed to (1) the pore connectivity effects that can be observed in materials with narrow pore mouths such as ink-bottle pores or (2) materials with uniform channel-like pores. , However, HP-MOFs with cage-like pores also show a type H2 hysteresis loop. , The type H3 hysteresis loop does not level off at high P / P 0 , and is normally observed in adsorption–desorption in plate-like aggregates with slit-shape pores, such as MOF and zeolite nanosheets. − HP-MOF MIL-125 with interparticle mesopores display a type H3 hysteresis loop in N 2 sorption tests at 77 K, as well . While the type H4 loop with paralleled horizontal sorption isotherms has been attributed to materials with narrow slit-like pores, HP-MOFs with mesopore sizes close to 20 nm also display the same type of hysteresis loop .…”

Amorphous metal–organic frameworks obtained from a crystalline precursor for the capture of iodine with high capacities

“…The resulting amorphous metal-organic frameworks (aMOFs), which have lost their long-range order lattices but retain a local structural motif similar to that of their crystalline counterpart, have attracted increasing attention. [5][6][7][8][9][10][11][12][13][14][15] On the one hand, after amorphization, the structure changes dramatically, and defects and additional pores may form, 8,15-17 leading to different performances. On the other hand, aMOFs are beneficial for processing and shaping, which are important for industrial applications.…”

“…On the other hand, a MOFs are beneficial for processing and shaping, which are important for industrial applications. 5 Although there is an increasing number of reports concerning the structure and formation of a MOFs 12,13 and their applications in the fields of drug delivery, 10 separation, 6,8,15 catalysis, 7,9 and so on, the number of reported a MOFs (less than 200) is small compared with those on crystalline MOFs (over 99 000). 15,18 Studies on a MOFs are largely unreported.…”