Formation of Rh islands on Pd-supported α-Fe2O3 (0001)

Abstract

A rhodium ultra-thin film was deposited on a Pd-supported α-Fe₂O₃ (0001) film by molecular beam epitaxy (MBE). The surface atomic and electronic structures were studied using X-ray photoelectron diffraction (XPD), X-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). For an oxide thin film (∼16.5 Å), an ordered (√3 × √3)R30° structure was observed. The multiple scattering calculation approach combined with a genetic algorithm for surface structure optimization was used to investigate precisely the atomic structure of the oxide support as well as the Rh nanoislands or nanoparticles (NPs). Rh exhibited 3D growth on an α-Fe₂O₃ thin film forming NPs with a lattice constant expanded by 5.26% relative to the Rh bulk value. The coexistence of 60° rotated domains and also evidence of Fe termination at the surface of α-Fe₂O₃ were observed.