Lattice-Plane-Dependent Distribution of Ce at Pt and CeO Interfaces for Pt/CeO Catalysts.

The interaction between a metal and a support, which is known as the metal-support interaction, often plays a determining role in the catalytic properties of supported metal catalysts. Herein, we have developed model Pt/CeO catalysts, which enabled us to investigate the interface atomic and electronic structures between Pt and the {001}, {011}, and {111} planes of CeO using scanning transmission electron microscopy and electron energy-loss spectroscopy. We found that the number of Ce ions around the Pt nanoparticles followed the order {001} > {011} > {111}, which was the opposite order of the generally accepted stability of low index surfaces of CeO. Systematic first-principles calculations revealed that the presence of Pt nanoparticles facilitated the formation of oxygen vacancies and that the appearance of the Pt state was preferred when Pt nanoparticles were in contact with CeO {001} planes due to direct charge transfer from Pt to CeO. These results provide important insights into the nature of the metal-support interaction for a comprehensive understanding of the properties of supported metal catalysts.