Oxygen vacancies on cerium oxide surfaces play a crucial role in catalysts for automotive exhaust treatment and the hydrogen economy. In their Perspective, Campbell and Peden describe new work ( Esch et al.) that uses scanning tunneling microscopy combined with density functional theory to reveal the geometric and electronic structure of these oxygen vacancies. Their structure suggests a mechanism for the rather surprising zirconia promotion of ceria catalysts.

Bonding Oxides and Metals: The binding of noble metals that can act as catalysts to metal oxides that are reducible is assumed to occur at the exposed cation of the oxide. For nonreducable oxides such as aluminum oxide, it is not so obvious how the metal can bind strongly. Kwak et al. (p. 1670 ) used a combination of high-resolution transmission electron microscopy and solid-state magic-angle spinning nuclear magnetic resonance to study the anchoring of platinum at high and low loadings on alumina. At the surface, the Al ³⁺ ions were penta-coordinated. Density functional calculations support a model in which the cation binds three oxygen atoms in the alumina and two from platinum oxide.