Support-facet-dependent morphology of small Pt particles on ceria

Abstract

Direct atomic scale information on how the structure of supported nanoparticles is affected by the metal–support interaction is rare. Using scanning transmission electron microscopy, we provide direct evidence of a facet-dependent support interaction for Pt nanoparticles on CeO₂, governing the dimensionality of small platinum particles. Our findings indicate that particles consisting of less than ∼130 atoms prefer a 3D shape on CeO₂(111) facets, while 2D raft structures are favored on CeO₂(100) facets. Measurements of stationary particles on both surface facets are supplemented by time resolved measurements following a single particle with atomic resolution as it migrates from CeO₂(111) to CeO₂(100), undergoing a dimensionality change from 3D to 2D. The intricate transformation mechanism reveals how the 3D particle disassembles and completely wets a neighboring CeO₂(100) facet. Density functional theory calculations confirm the structure-trend and reveal the thermodynamic driving force for the migration of small particles. Knowledge of the presented metal–support interactions is crucial to establish structure–function relationships in a range of applications based on supported nanostructures.