CO and D2O chemistry on continuous and discontinuous samaria thin films on Pt(111)

摘要

The chemistry of CO and D2O, individually adsorbed or co-adsorbed, on epitaxial thin films of samaria on Pt(111) was studied by temperature-programmed desorption spectroscopy (TPD). Continuous thin films as well as discontinuous films composed of samaria islands on bare Pt(111) were prepared. Their comparative study indicates that Sm2O3 islands provide lattice oxygen at their perimeter for CO oxidation on adjacent exposed Pt area where CO adsorption takes place. CO2 production was observed only on as-prepared discontinuous films. While, in particular on thermally reduced samaria islands, TPD after D2O adsorption revealed D-2 production which indicates a pathway for D2O dissociation, no evidence for the water gas shift reaction of CO and residual OD species on the surface was found after co-adsorption of CO and D2O. Instead, interaction between CO and OD species at the perimeter of islands on reduced discontinuous SmOx thin films obviously promotes D-2 formation without yielding CO2 as desorbing product. (C) 2016 Elsevier B.V. All rights reserved.