Design strategies for metal alkoxide functionalized metal–organic frameworks for ambient temperature hydrogen storage

Grand canonical Monte Carlo simulations were used to calculate hydrogen adsorption in IRMOF-16, NU-100, and UiO-68 functionalized with Mg or Fe catecholates on the linkers. We examined how altering the number of metal catecholate groups affects H2 uptake and deliverable capacity near ambient temperature. We find that large free volume and an isosteric heat of adsorption (Qst) of 20 kJ mol−1 at low loading will maximize gravimetric deliverable capacity while a small pore diameter will maximize volumetric deliverable capacity. This suggests a trade-off between the properties that lead to maximal gravimetric and volumetric capacities. For example, our calculations suggest that NU-100 functionalized with six Fe catecholate groups per linker takes up 5.5 wt.% deliverable H2 at 243 K and 100 bar, but only 24.2 g L−1 deliverable H2.

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► Computationally studied different metals in linkers of MOFs for hydrogen storage.
► Studied the effect of different metal loadings on hydrogen uptake.
► Results suggest a trade-off between gravimetric and volumetric capacities.
► We propose useful design rules for improving hydrogen storage in MOFs.