Integrating Molecular Simulations and Experiments to Explore Hydrogen Adsorption and Storage in Fluorous Metal–Organic Frameworks

Hydrogen (H2) stands out as the most promising clean, renewable energy source with a net zero carbon emission. Cryogenic H2 storage for on-board vehicle applications using metal–organic frameworks (MOFs) has become a practical option with a good balance of safety, affordability, and efficiency. Before conducting extensive trials for vehicular fuel applications, it is crucial to understand the H2 adsorption mechanism in MOFs using molecular simulations. In this work, we provide an integrated simulation and experimental investigation of H2 uptake and storage in a series of fluorous MOFs, including the reference point structure FMOF-1a, three expansion models thereof previously obtained experimentally (FMOF-1b, FMOF-1c, and FMOF-2), and a uniform small-pore structure (FMOF-4)─all for the same 3,5-bis(trifluoromethyl)-1,2,4-triazolatosilver(I) complex empirical formula. Grand Canonical Monte Carlo simulations were employed to predict the adsorption isotherms at 77, 160, and 298 K, up to a pressure of 100 bar. Among different H2 adsorption models simulated, the Darkrim and Levesque model agrees best with experimental adsorption data. While FMOF-1b is predicted to exhibit a greater affinity for H2, as revealed by its higher Henry’s constant (KH) and isosteric heats of adsorption at infinite dilution (Qst0), the highest H2 uptake is projected for FMOF-2. Radial distribution function and density distribution analyses suggest that H2 molecules adsorb preferentially in the small cavity region in FMOF-1b, FMOF-2, and FMOF-4. On the other hand, in FMOF-1a and FMOF-1c, the large channels are the preferred binding sites for H2. FMOF-2 exhibits the highest volumetric deliverable capacity (35.27 g L–1) under temperature- and pressure-swing conditions, highlighting its potential for practical cryogenic H2 storage in on-board vehicle applications.