We report the preparation and electrocatalytic performance of silver-containing gas diffusion electrodes (GDEs) derived from a silver coordination polymer (Ag-CP). Layer-by-layer growth of the Ag-CP onto porous supports was applied to control Ag loading. Subsequent electro-decomposition of the Ag-CP resulted in highly selective and efficient CO₂-to-CO GDEs in aqueous CO₂ electroreduction. Afterward, the metal-organic framework (MOF)-mediated approach was transferred to a gas-fed flow electrolyzer for high current density tests. The in situ formed GDE, with a low silver loading of 0.2 mg cm^-2, showed a peak performance of j_CO ≈ 385 mA cm^-2 at around -1.0 V vs RHE and stable operation with high FE_CO (>96%) at j_Total = 300 mA cm^-2 over a 4 h run. These results demonstrate that the MOF-mediated approach offers a facile route for manufacturing uniformly dispersed Ag catalysts for CO₂ electrochemical reduction by eliminating ill-defined deposition steps (drop-casting, etc.) while allowing control of the catalyst structure through self-assembly.

During the last decade, the synthesis and application of metal-organic framework (MOF) nanosheets has received growing interest, showing unique performances for different technological applications. Despite the potential of this type of nanolamellar materials, the synthetic routes developed so far are restricted to MOFs possessing layered structures, limiting further development in this field. Here, a bottom-up surfactant-assisted synthetic approach is presented for the fabrication of nanosheets of various nonlayered MOFs, broadening the scope of MOF nanosheets application. Surfactant-assisted preorganization of the metallic precursor prior to MOF synthesis enables the manufacture of nonlayered Al-containing MOF lamellae. These MOF nanosheets are shown to exhibit a superior performance over other crystal morphologies for both chemical sensing and gas separation. As revealed by electron microscopy and diffraction, this superior performance arises from the shorter diffusion pathway in the MOF nanosheets, whose 1D channels are oriented along the shortest particle dimension.

The performance of mixed-matrix membranes (MMMs) based on Matrimid^® and benzimidazole-linked polymers (BILPs) have been investigated for the separation CO₂/N₂ and the dependency on the filler porosity. BILPs with two different porosities (BILP-101 and RT-BILP-101) were synthesized through controlling the initial polymerization rate and further characterized by several techniques (DRIFTs, ¹³C CP/MAS NMR, SEM, TEM, N₂ and CO₂ adsorption). To investigate the influence of porosity, the two types of fillers were incorporated into Matrimid^® to prepare MMMs at varied loadings (8, 16 and 24 wt%). SEM confirmed that both BILP-101 and RT-BILP-101 are well dispered, indicating their good compatibility with the polymeric matrix. The partial pore blockage in the membrane was verified by CO₂ adsorption isotherms on the prepared membranes. In the separation of CO₂ from a 15:85 CO₂:N₂ mixture at 308 K, the incorporation of both BILPs fillers resulted in an enhancement in gas permeability together with constant selectivity owing to the fast transport pathways introduced by the porous network. It was noteworthy that the initial porosity of the filler had a large impact in separation permeability. The best improvement was achieved by 24 wt% RT-BILP-101 MMMs, for which the CO₂ permeability increases up to 2.8-fold (from 9.6 to 27 Barrer) compared to the bare Matrimid^®.

C₁₄H₁₆N₂O₆, triclinic, P1 (no. 2), a = 10.0254(5) Å, b = 11.2726(6) Å, c = 13.4494(7) Å, α = 111.535(2)°, β = 92.068(2)°, γ = 102.644(2)°, V = 1368.16(13) ų, Z = 4, R_gt(F) = 0.047, wR_ref(F²) = 0.133, T = 150 K.

Three supramolecular isomers of lutetium metal-organic framework, {Lu₂(H₂O)₄(ATA)₃·4H₂O}_n (Lu-ATA@RT), {Lu₂(H₂O)₂(C₃H₇NO)₂(ATA)₃}_n (Lu-ATA@100), and {Lu₂(C₃H₇NO)(ATA)₃}_n (Lu-ATA@150), have been obtained from the reaction of Lu(NO₃)₃·6H₂O with 2-aminoterephthalic acid (ATA) at different temperatures. The resulting structures of Lu-ATA metal-organic frameworks depend on the temperature applied during the synthesis, revealing a temperature-susceptible supramolecular isomerism. Single-crystal X-ray diffraction analyses suggest that new compounds with formula {Lu₂(S)_x(ATA)₃}_n (S = solvent: H₂O, DMF) display different three-dimensional architectures which consist of dinuclear lutetium building units. The supramolecular isomer Lu-ATA@RT, formed at room temperature, has a pcu-net topology, while its double interpenetrated analogue Lu-ATA@100 assembles at 100 °C under hydrothermal conditions. Hydrothermal synthesis at 150 °C affords formation of the dense Lu-ATA@150 cage-like framework displaying a new hexagonal-packed net topology. All Lu-ATA isomeric phases are porous and display different gas-uptake behavior toward carbon dioxide as a function of polymeric network arrangement. The luminescent properties of Lu-ATA frameworks in the solid state as well as in suspension in the presence of different solvents reveal a solvent-dependent emission.

Incorporation of Ca in ZSM-5 results in a twofold increase of propylene selectivity (53 %), a total light-olefin selectivity of 90 %, and a nine times longer catalyst lifetime (throughput 792 g_MeOH g_catalyst ⁻¹) in the methanol-to-olefins (MTO) reaction. Analysis of the product distribution and theoretical calculations reveal that post-synthetic modification with Ca²⁺ leads to the formation of CaOCaOH⁺ that strongly weaken the acid strength of the zeolite. As a result, the rate of hydride transfer and oligomerization reactions on these sites is greatly reduced, resulting in the suppression of the aromatic cycle. Our results further highlight the importance of acid strength on product selectivity and zeolite lifetime in MTO chemistry.

The front cover artwork for Issue 19/2016 is provided by researchers from the Catalysis Engineering group at TU Delft (The Netherlands). The image shows that after impregnation with Ca, ZSM-5 becomes a “super-catalyst”, which is able to suppress formation of aromatics thus increasing selectivity to the desired propylene in MTO reaction. See the Full Paper itself at http://dx.doi.org/10.1002/cctc.201600650.