Optimized synthesis of Zr(IV) metal organic frameworks (MOFs-808) for efficient hydrogen storage

Nanostructured Zr(IV) metal organic frameworks (MOFs-808) with high stability are synthesized by using trimesic acid (BTC), a highly electron-deficient and polar molecule, as an organic ligand in order to produce efficient adsorbents for hydrogen gas. The MOFs-808 are characterized by XRD, FT-IR, SEM, TEM, specific surface area measurements and thermogravimetric analysis, and the conditions (e.g., the reactant molar ratio, the amount of solvent, the reaction temperature and the reaction time) for synthesis of MOFs-808 are optimized. The MOF-808 obtained under optimized preparation conditions has higher crystallinity, a larger specific surface area, and relatively high stability both in acidic solution and at temperatures up to 300 °C. The hydrogen storage capacity of the optimized MOF-808 under 4 MPa reaches 7.31 wt% at 77 K, which is close to the ultimate target defined for hydrogen storage. Our results indicate that the presence of the electron-deficient ligand on MOFs-808 favors the adsorption of hydrogen gas.