Adsorption of Hydrogen onto Bare and Metal Decorated Metal Oxides

Catalytically relevant metal clusters were deposited on metal oxide supports. Palladium and gold were deposited on mixed morphology ZnO, and palladium was deposited on MgO(100). The materials were characterized with electron microscopy, photoluminescent spectroscopy, and X-ray photoelectron spectroscopy. The behavior of hydrogen on these materials, as well as bare ZnO, was studied using volumetric isotherms. The isotherms were used to determine the monolayer gas coverage, surface

area, and heats of adsorption of hydrogen on these materials over the temperature range of approximately 8-13 K. At the temperatures and pressures studied, hydrogen physically adsorbed onto the materials. Additional investigations with inelastic neutron scattering were conducted on palladium decorated ZnO and bare ZnO. These revealed that hydrogen molecules on bare ZnO act as three dimensional free rotors, but hydrogen on palladium decorated ZnO acts as a two-dimensional planar molecule and undergoes a 6.2% bond length extension.