Delivering methane and hydrogen: The pressure for onboard storage of methane and hydrogen on vehicles is usually limited to 100 bar for the use of lightweight containers, but the amount stored can be increased with the use of absorbent materials. Efficient storage and delivery require a balance of volumetric and gravimetric storage. Chen et al. designed a metal-organic framework with trialuminum nodes and a large hexadentate aromatic linker that optimizes both parameters. This material surpassed the U.S. Department of Energy targets for methane and had a deliverable capacity of 14% by weight for hydrogen. Science , this issue p. 297
Direct air capture is regarded as a plausible alternate approach that, if economically practical, can mitigate the increasing carbon dioxide emissions associated with two of the main carbon polluting sources, namely stationary power plants and transportation. Here we show that metal-organic framework crystal chemistry permits the construction of an isostructural metal-organic framework (SIFSIX-3-Cu) based on pyrazine/copper(II) two-dimensional periodic 4(4) square grids pillared by silicon hexafluoride anions and thus allows further contraction of the pore system to 3.5 versus 3.84 Å for the parent zinc(II) derivative. This enhances the adsorption energetics and subsequently displays carbon dioxide uptake and selectivity at very low partial pressures relevant to air capture and trace carbon dioxide removal. The resultant SIFSIX-3-Cu exhibits uniformly distributed adsorption energetics and offers enhanced carbon dioxide physical adsorption properties, uptake and selectivity in highly diluted gas streams, a performance, to the best of our knowledge, unachievable with other classes of porous materials.