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.

The adsorption of NO and NO₂ and the reaction between NO and O₂were investigated on a Na-Y,FAU zeolite. The interaction between NO and Na-Y is weak and no IR absorption feature is seen upon room temperature adsorption. On the other hand, several NO_x species were identified in the adsorption of NO₂ bonded to Lewis acidic (NO₃ ⁻, NO₂ ⁻) and basic sites (NO⁺ and [NO⁺][NO₂] and [NO⁺][N₂O₄]). In the NO + O₂ reaction, N₂O₃ was formed and adsorbed N₂O₃ was observed in addition to the species detected upon NO₂ adsorption. A series of experiments were conducted to unambiguously assign the IR features in the 2000–2120 cm⁻¹ spectral range. Through reaction and isotopic substitution (¹⁵NO and ¹⁸O₂) experiments, these bands were assigned to NO⁺ adsorbed onto framework O⁻ sites as charge compensating cations.