Hydrogen storage in a potassium-ion-bound metal-organic framework incorporating crown ether struts as specific cation binding sites.

Abstract

To develop a metal-organic framework (MOF) for hydrogen storage, SNU-200 incorporating a 18-crown-6 ether moiety as a specific binding site for selected cations has been synthesized. SNU-200 binds K(+), NH4(+), and methyl viologen (MV(2+)) through single-crystal to single-crystal transformations. It exhibits characteristic gas-sorption properties depending on the bound cation. SNU-200 activated with supercritical CO2 shows a higher isosteric heat (Qst) of H2 adsorption (7.70 kJ mol(-1)) than other zinc-based MOFs. Among the cation inclusions, K(+) is the best for enhancing the isosteric heat of the H2 adsorption (9.92 kJ mol(-1)) as a result of the accessible open metal sites on the K(+) ion.