A first-principles molecular dynamics study on the surface lattice oxygen of ceria

Abstract

Cerium dioxide (CeO2) has a wide range of applications in the field of heterogeneous catalysis. Different facets can be exposed at CeO2 nanomaterials with different morphologies, and these facets can exhibit very different catalytic activities. Previous studies focusing on the activities of various CeO2 facets largely relied on the calculated energetics such as surface energies and oxygen vacancy formation energies, and the activities of the low-index CeO2 surfaces obtained in these ways follow the order (110) > 2 × 1 reconstructed (110) > (111). In this work, in order to more thoroughly examine the surface physicochemical properties, we used a combination of molecular dynamics (MD) and density functional theory calculations to systematically study the mobilities of different oxygen atoms on the three CeO2 surfaces under relatively high temperatures. The O mobilities have been studied by means of MD trajectories as well as the coordination number analysis. The results indicate that the exposed unsaturated O atoms at reconstructed CeO2(110)-2 × 1 can exhibit extraordinary mobilities, and they also suggest that besides the bonding strength, the distribution patterns of surface O atoms might be able to affect their activities as well.