Energy Environ. Sci. http://doi.org/bqwd (2016)

Improving on-board hydrogen storage technologies is one of the main challenges associated with the continued development of fuel cell vehicles. Although present technology uses compressed hydrogen gas (CHG) at 700 bar and ambient temperature, using porous materials to cryo-adsorb hydrogen at lower pressures is being explored. Metal-organic frameworks (MOFs) are promising candidates, but materials with higher volumetric and gravimetric capacity would be preferable. Now, Taner Yildirim, Omar Farha, Jian Zhang, Randall Snurr and colleagues across the US predict that deliverable hydrogen capacities of 57 g L−1 for MOFs should be possible using cryogenic operating conditions, surpassing the value of 37 g L−1 realized in current technology.

The researchers first computationally construct a set of over 13,000 MOFs comprising a range of known and new structures, and then calculate the deliverable hydrogen capacity using molecular simulations, assuming hydrogen is adsorbed at 100 bar, 77 K and desorbed at 5 bar, 160 K. At these operating conditions, they find that many MOFs are superior to CHG at 700 bar. Guided by these results, they synthesize a subset of structures, including a new family of MOFs based on an unusual topology. Out of these, a previously prepared MOF (NU-1103) exhibits a volumetric capacity of 43 g L−1, combined with promising stability and gravimetric capacity.