Enhancing Volumetric Hydrogen Storage Capacity through Bimodal Packing of MOF Particles

Packing density critically influences the practical hydrogen storage capacity of metal–organic frameworks (MOFs), yet it is often overlooked in volumetric performance evaluations. In this study, we demonstrate that bimodal particle packing provides an effective route to enhance system-level volumetric hydrogen storage by reducing interparticle voids. A V3(PET) MOF was synthesized in two distinct sizes (∼9 μm and ∼300 nm) to construct a bimodal particle system. Discrete element method (DEM) simulations were used to establish particle-packing design rules and to identify the optimal mixing composition for maximizing packing density. These simulation-guided predictions were then experimentally validated through tapping density measurements and high-pressure H2 adsorption isotherms. The optimized bimodal mixture achieved a packing fraction of 0.56, compared to 0.42 for unimodal packing, leading to a 33–38% increase in volumetric excess hydrogen uptake at 77 K. Moreover, the bimodal system exhibited an enhanced working capacity of up to 37.7 g/L under pressure–temperature swing adsorption (PTSA) condition (160 K 5 bar to 77 K 100 bar). These results demonstrate particle-level packing engineering as a broadly applicable and experimentally accessible strategy for bridging intrinsic MOF properties with realistic, system-level hydrogen storage performance.