Enhancing Hydrogen Adsorption Ability of MOF-5 with Metal Node Exchange and Linker Functionalisation

Abstract

In the search for promising material candidates for hydrogen storage, we investigate from first principles derivatives of metal organic framework 5 (MOF-5), including isoelectronic substitution of the metal centers (Zn $\to$ Mg, Cd) and linker functionalization with NH${}_2$, OH, and NO${}_2$ groups. Metal-node substitution consistently stabilises and ligand functionalization systematically enhances H${}_2$ binding at the metal-oxo cluster sites. The combination of Cd centers and NO${}_2$ groups proves to be most efficient, yielding an adsorption energy of -15.58 kJ mol${}^{\text{-1}}$, which substantially outperforms the storage ability of pristine MOF-5. Detailed electronic structure analysis clarifies how the local framework environment coordinates the guest molecule, providing a robust design framework to guide the experimental development of advanced adsorbent materials.