Uranium oxides are the prototypical actinide oxide that has received the widest attention to its surface chemistry as a result of its unique redox chemical properties. Previous studies have been devoted to the single crystal (111) surfaces of predominantly UO2 (U4+) as well as numerous polymorphs of uranium oxide polycrystalline surfaces including U3O8 (U4+/U6+), UO3 (U6+) and U metal (1). The ability to readily donate or harvest oxygen, easily interchangeable stable oxidation states (4+/6+) and the availability of a large number of electrons (5f) are key to being a rich catalytic material. This work looks at surfaces of well-defined (100) surfaces of UO2 and U3O8 that are far less energetically favorable than the (111) equivalents. The surfaces are prepared via polymer assisted deposition (PAD) technique over a-Al2O3 (UO2) and LaAlO3 (U3O8) resulting in single phased epitaxial films (100nm) that has been characterized with HRTEM, XRD and LEED (2). The chemistry of these (100) films have been studied with respect to heterogeneous interaction of oxygenated molecules (H2O, R-OH) using synchrotron based XPS. We report the adsorption and desorption of molecules from these surface as observed in the C1s and O1s regions and make comparisons to studies undertaken on (111) single crystal surfaces (3-4). Idriss H., Surf. Sci. Reps. (2011), 65, 67-109.Burrell A.K. et al., Adv. Mater. (2007), 19, 3559�3563.Senanayake S.D. et al. Surf. Sci. (2004), 563, 135-144.Chong S.V. et al. Surf. Sci. (2000), 444, 187-198.

Surface reactions of UO2(100) and U3O8(100) thin films

244th National Meeting (2012)

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