Oxygen activation on oxide surfaces: A perspective at the atomic level

• Oxygen activation on oxides.
• Scanning tunneling microscopy of O2 on MgO.
• Structure–reactivity relations for methanol oxidation on supported vanadia.
• Spectroscopy–structure relations supported vanadia.

Thin oxide films have been used as model supports to unravel the influence of the oxide–metal and oxide–gas interface. We discuss the influence of defects in the oxide lattice and the oxide surface on properties of adsorbed species, in particular the formation of oxide particles from a deposited transition metal onto ceria and of adsorbed oxygen from the gas phase. Here we correlate the structure of the particles, as revealed by a combination of STM and spectroscopic as well as theoretical calculations, with their reactive properties. The nature of the involved defects is characterized by adsorption of Au as a way to correlate the influence of various defects of different structure on the Au charge state. In a second case study, we demonstrate the influence of dopants within the supporting oxide on the adsorption of oxygen on a defect free surface. This is shown to be potentially relevant for the activation of methane in oxidative methane coupling reactions, as recently demonstrated.

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