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The goal of this project is to better understand the physisorption mechanism that traps molecular hydrogen within a host material. The main motivation is practical in terms of hydrogen storage for fuel cell applications but there is also a fundamental interest in understanding the nature of the van der Waals forces within complex structures. The technique, infrared (IR) spectroscopy, is quite unusual for this field of work in that H2 does not possess a dipole moment and is thus IR inactive. However hydrogen-host interactions may induce dipole moments leading to observable (albeit quit weak) IR absorption bands. Our use of a novel diffuse reflectance geometry has allowed us to overcome this difficulty posed by the weak nature of the absorption bands. We have chosen to study a promising class of materials known as metal-organic-frameworks (MOFs) consisting of metal-oxide clusters connected by organic linkers The great appeal of these materials is that both the inorganic clusters and organic linkers can be readily modified to form a vast array of possible structures. These are highly crystalline with large accessible pore space for molecular storage. Our initial work focusing on a zinc based MOF known as MOF-5 (the field standard) was published in Physical Review. This paper established the relationship between the frequency red shift of the hydrogen vibrational mode and its binding energy at a particular host site. The site by site binding energy is the key parameter that needs to be understood and enhanced for better hydrogen storage materials. We then extended this work to three other MOF compounds, ZIF-8, HKUST-1, and MOF-74. This allowed us to compare and contrast the dynamics of hydrogen within these different materials and in particular the quantum effects of isotopic substitution with HD and D2. MOF-74 proved the most exciting since the material can be formed in an isostructural series in which the crystalline structure is unchanged, but the metal cation can be changed from one member of the series to another. This summer we fabricated and investigated the Mg, Mn, Co, Ni, and Zi versions of the material. This revealed that the hydrogen first binds at the metal site, producing an infrared spectrum that varies systematically on going from one member of the series to the next. In contrast the behavior of the hydrogen at secondary sites is almost unchanged throughout the series. We are presently preparing these results for publication.