Enhanced H2 Adsorption in Isostructural Metal-Organic Frameworks with Open Metal Sites: Strong Dependence of the Binding Strength on Metal Ions

Abstract

Porous metal-organic frameworks (MOFs) have exhibited great potential for gas storage.1 The largest drawback of this class of materials for H2 storage application is their weak binding strength to H2, which necessitates a cryogenic working temperature. Extensive efforts thus have been made to synthesize new MOFs with enhanced H2 affinity. A successful endeavor would require a good understanding of the H2 interactions with both metal clusters and organic linkers. One effective route to achieve this goal is to systematically compare isostructural MOFs with various building units. Isostructural MOFs with the same metals but different organic linkers are fairly common (e.g., the IRMOF-1 to IRMOF-16 series2), and comparison studies of the H2 adsorption on such MOFs have been carried out routinely.3 In contrast, isostructural MOFs with different metals are rare, mainly due to the sensitivity of the synthetic reaction to the coordination chemistry of the metal ions