Interaction of Hydrogen with Cu-Modified Cerium Oxide Surfaces

We investigate the interaction between molecular hydrogen and ultrathin epitaxial CeO2 films modified with a 2% concentration of Cu atoms using X-ray photoemission spectroscopy (XPS) during thermal reduction cycles in H2. The XPS measurements are combined density functional theory calculations to obtain further insight into observed modifications film surface. Our results show that presence decreases barrier for H2 dissociation comparison on pure ceria surfaces, leading formation surface OH groups after exposure Moreover, oxygen vacancies generated already at mild temperatures (470 K), most likely via water desorption. hydroxyls contributes large increase Ce3+ increasing temperature. In spite these atomic scale modifications, morphology by scanning tunneling microscopy remains substantially unchanged length tens nm.