Gas Adsorption Snapshots in Metal–Organic Frameworks Unveil the Impact of Pore Geometry on Hydrogen Storage

Metal–organic frameworks (MOFs) are promising candidates for hydrogen (H2) storage. However, effective H2 storage in MOFs is challenging, because of weak adsorbent–adsorbate interactions. Optimizing the pore volume, size, and functionality in porous MOFs is crucial, but it is still unclear how to maximize H2 storage capacity while minimizing loading pressure. Herein, we investigate Al-TBAPy (H4TBAPy: 1,3,6,8-tetrakis(p-benzoic acid)pyrene), a low-density MOF, for H2 storage. Al-TBAPy features three interconnected pores (A–C), possesses a pore volume of 0.51 cm3/g, and demonstrates a H2 uptake of 22.5 mmol/g at 77 K and 100 bar. In situ deuterium (D2) gas loading neutron diffraction experiments reveal molecular-level insights into pore filling. Pores B and C exhibit high H2 affinity, while pore A, with a larger volume, takes up more H2 molecules. The collective properties of all pores and their interconnection result in a high deliverable gravimetric H2 capacity of 4.3 wt % under combined temperature and pressure swing conditions.