Growth and interface formation in CeO _x -Ni(111) inverse model catalysts

We investigated the inverse catalyst configuration CeO _x /Ni(111) by combining diffraction, spectroscopic, and imaging techniques to obtain a complete picture of the growth mode. Our results from quantitative X-ray photoelectron spectroscopy, low-energy electron diffraction, and scanning tunneling microscopy reveal a complex system in which the initial oxidation of the Ni substrate plays a fundamental role in the preferred orientation of ceria and its initial reduction. We demonstrate the formation of a NiO(111) interfacial layer between the CeO _x (111) wetting layer and the Ni substrate, while thicker cerium oxide islands nucleate at step edges. Furthermore, we found evidence of oxygen migration and electronic charge transfer at the interface, resulting in a CeO _x /NiO interface rich in Ce³⁺ states. These results highlight the complex structural and electronic interactions established between the film and the substrate, offering deeper insights into the underlying interfacial physics and chemistry of ceria-nickel catalysts.