CO oxidation over ZnO films on Pt(1 1 1) at near-atmospheric pressures

Well-ordered ultrathin ZnO(0 0 0 1) films were grown on Pt(1 1 1) in a layer-by-layer mode. The reactivity of the films as a function of the film thickness and coverage was examined by the CO oxidation reaction at near-atmospheric pressures. At low temperatures (∼450 K), CO2 production is found to be much higher on the films of partial coverage than on dense ZnO(0 0 0 1) films and bare Pt(1 1 1). Under reaction conditions, monolayer islands and an entire monolayer film transform into two-monolayers-thick islands, which dominate the surface of the active catalysts. The results provide an adequate structural model for elucidating the reaction mechanism on the oxide/metal boundary at technologically relevant conditions.

Graphical abstractThe atomic structure and reactivity of zinc oxide ultrathin films on Pt(1 1 1) was examined by the CO oxidation reaction at near-atmospheric pressures as a function of the film thickness and coverage. The observed structure-reactivity relationships directly show that the boundary between a metal and a two-layers-thick oxide (see figure) provides the most active sites for this reaction.Figure optionsDownload full-size imageDownload high-quality image (93 K)Download as PowerPoint slideHighlights► Thin films of ZnO were grown on Pt(1 1 1) in a layer-by-layer mode. ► The CO oxidation reaction at near-atmospheric pressures as a function of the film thickness and coverage was studied. ► Two-monolayers-thick ZnO(0 0 0 1) islands dominate the surface of the most active catalysts. ► Direct proof for the oxide/metal boundary providing the active sites.