Metal supported oxide nanostructures: model systems for advanced catalysis
Metal supported oxide nanostructures are discussed within the framework of the "inverse model catalyst" concept. We show that oxide nanostructures on metal surfaces may be regarded as artificial oxide materials, which display novel properties as compared to bulk oxide compounds and are stabilised by interfacial interactions and two dimensional confinement effects. This is illustrated for prototypical examples of vanadium oxide overlayers on Rh(111) and Pd(111) surfaces. Structure and morphological changes of the oxide phase on V oxide/Rh and V oxide/Pd inverse catalyst surfaces are discussed, and the mass transport problem in catalyst systems during oxidation reduction cycles is addressed. We demonstrate that the diffusion of oxide cluster over the metal surface provides a effective means of mass transport. The role of metal oxide interface in determining the oxide nanolayer structure on particular substrate surfaces is investigated, and interfacial chemistry and interfacial strain effects are identified as important parameters.