The role of sticking efficiencies in hydrogen gas adsorption on metal organic frameworks

• The type of linker is an important factor in H2 gas adsorption on MOFs.
• A parameter denoted sticking efficiency correlates well with H2 adsorption capacity.
• Sticking efficiency correlates well with the H2 adsorption enthalpy.
• Sticking efficiency is a measure of the hydrogen binding energy on MOFs.

In this study, the adsorption of hydrogen gas on 17 MOFs was compared. The majority of the MOFs contained carboxylate type linkers and metal centers such as Cu and Zn. A new parameter denoted sticking efficiency was used to compare the adsorption behaviors of the 17 MOFs. Results showed that a better correlation exists between sticking efficiency and hydrogen adsorption capacity than between surface area and adsorption capacity. However, when only MOFs containing similar types of linkers were included in the comparison, the surface area correlated somewhat better with adsorption capacity than did sticking efficiency. Since a direct correlation was also found between the sticking efficiency and the adsorption enthalpy it appears that sticking efficiency is a measure of the binding energies of the MOFs.

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