Unraveling the Interaction between Fe and CeO₂(111) through Growth, Structure, and Thermal Stability Studies

Fe on CeO2, inheriting the oxygen storage/release capacity of ceria and the catalytic activity of Fe with various d orbitals, has been widely used in heterogeneous catalysis. To explore the morphological and electronic structures of the ceria supported iron model catalyst, we employed X-ray photoelectron spectroscopy (XPS), synchrotron radiation photoemission spectroscopy (SRPES), scanning tunneling microscopy (STM), and low energy electron diffraction (LEED) to comprehensively investigate the growth, structure, and thermal stability of Fe deposited onto 3 nm thick well-ordered CeO2(111) thin films grown on Cu(111) at room temperature. At low coverage, Fe clusters tend to a two-dimensional random growth on CeO2(111). Charge transfer occurs between Fe and CeO2(111), leading to the oxidation of Fe to Fe2+ and reduction of Ce4+ to Ce3+. The average charge per Fe atom and local surface dipole indicate the formation of Fe–O–Ce mixed oxides instead of FeO at the interface. Notably, an unprecedented (2/3 × 2/3)-R30° wetting layer can be identified at high Fe coverage at 420 K. The evolutions of electronic and morphological structures of Fe on CeO2(111) provide deep insight into the metal–support interactions.