Surface-termination-dependent Pd bonding and aggregation of nanoparticles on LaFeO3 (001)

The bonding and morphology of Pd clusters deposited on the LaO- and FeO2-terminated LaFeO3 (001) surface were studied using periodic density functional methods together with scanning transmission electron microscopy. We show that Pd tends to aggregate to three-dimensional (3D) clusters on both terminations since the Pd-Pd cohesive energy is larger than the Pd-LaFeO3 adhesive energy. However, from the kinetic point of view, Pd migration on the LaO termination is facile, while stronger interactions between Pd and the FeO2 termination significantly hinder the migration of Pd. Furthermore, molecular dynamics simulations demonstrate that Pd would agglomerate into 3D metallic and PdOx particles on the LaO and FeO2 terminations, respectively, and hint at the possibility of partial penetration of the PdOx particles into the surface, as observed experimentally.