Metal–organic frameworks (MOFs) are hybrid organic–inorganic nanoporous materials that exhibit regular crystalline lattices with relatively well-defined pore structures. Chemical functionalization of the organic linkers in the structures of MOFs affords facile control over pore size and chemical/physical properties, making MOFs attractive for a variety of industrial applications including membrane-based gas separations. A wealth of reports exists discussing the synthesis and applications of MOFs; however, relatively few reports exist discussing MOF membranes. This disparity owes to challenges associated with fabricating films of MOF materials, including poor substrate–film interactions, moisture sensitivity, and thermal/mechanical instability. Since even nanometer-scale cracks and defects can affect the performance of a membrane for gas separation, these challenges are particularly acute for the fabrication of MOF membranes. Here, we review recent progress on MOF membranes with an emphasis on their fabrication techniques, challenges involved in membrane synthesis, reported strategies to address these challenges (issues), and gas separation performance. Finally, we conclude with our perspectives on future research directions in this area.

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This paper reports data on a number of more challenging potential direct proton exchange membrane (PEM) fuel cell fuels using standard membrane electrode assemblies. We have demonstrated that methane, and also molecules that can be conventionally catalytically dehydrogenated, can produce activity in PEM fuel cells. Methane and cyclohexane can be electrochemically oxidized but poorly. For the first time we have demonstrated that hydrogen storage compounds, N-ethyl-dodecahydrocarbazole, and dodecahydrofluorene -as the neat liquids, can be oxidized in fuel cells. The high OCV shows that the thermodynamics are very favorable for using the compounds in a direct PEM fuel cell setup. However, it is clear from this work that considerably more research is needed for devising adequate electrooxidation catalysts for these hydrogen-regenerable fuels. Direct hydroquinone fuel cells using a PtRu catalyst system where hydroquinone is oxidized to benzoquinone are demonstrated. The effects of temperature, pressure and feed concentration on the fuel cell performance were evaluated. At a 20 psi back pressure, 80 • C cell temperature and 0.5 M feed concentration with a PtRu oxidation catalyst an open circuit potential of 297 mV was observed with a maximum current density of 15 mA/cm 2 at 100 mV.

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