Subsurface Oxygen Stabilization by a Third Species: Carbonates on Ag(210)

Subsurface species have often been invoked to explain the activation of catalytic surfaces for specific reactions. In particular, subsurface oxygen is thought to be important for the chemistry of Ag catalysts. Here we show by experimental and theoretical methods that on Ag(210) subsurface oxygen is stabilized by carbonates more efficiently than by O adatoms, thus leading to a concentration up to 4 times larger in the presence of the former adsorbate. Experimentally, a maximum of six subsurface O atoms are found to be stabilized by each carbonate. These results might be relevant for the current efforts to bridge the structure and pressure gaps between surface science and industrial conditions, for which non-negligible amounts of carbonates are surely present.