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 (H 2 ) storage. However, effective H 2 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 H 2 storage capacity while minimizing loading pressure. Herein, we investigate Al-TBAPy (H 4 TBAPy: 1,3,6,8-tetrakis( p -benzoic acid)pyrene), a low-density MOF, for H 2 storage. Al-TBAPy features three interconnected pores (A–C), possesses a pore volume of 0.51 cm 3 /g, and demonstrates a H 2 uptake of 22.5 mmol/g at 77 K and 100 bar. In situ deuterium (D 2 ) gas loading neutron diffraction experiments reveal molecular-level insights into pore filling. Pores B and C exhibit high H 2 affinity, while pore A, with a larger volume, takes up more H 2 molecules. The collective properties of all pores and their interconnection result in a high deliverable gravimetric H 2 capacity of 4.3 wt % under combined temperature and pressure swing conditions.