Cerium oxide layers on the Cu(1 1 1) surface: Substrate-mediated redox properties

Ceria submonolayers consisting of nanosized 2D islands on a Cu(1 1 1) surface have been prepared by oxidation of the nucleating Ce submonolayer (0.7 ML) and characterized using XPS and STM. The reducibility of the resulting well-defined CeO2−x/Cu(1 1 1) model system of the “inverse supported catalyst” type was studied by XPS using CO as reducing agent. In order to investigate the contribution of the substrate in the redox process, the properties of a ceria submonolayer (0.7 ML) on Cu(1 1 1), of an optically dense layer of ceria (1.5 ML) on Cu(1 1 1) and of a ceria submonolayer (0.7 ML) on Pt(1 1 1) have been compared. The direct comparison reveals the (metal substrate mediated) spillover mechanism of the ceria reduction by CO in the present CeO2−x/Mefcc(1 1 1) model systems.