Distinct Physicochemical Properties of the First Ceria Monolayer on Cu(111)

Discontinuous ceria layers on Cu(111) represent heterogeneous catalysts with notable activities in water-gas shift and CO oxidation reactions. Ultrathin ceria islands in these catalysts are composed of monolayers of ceria exhibiting CeO2(111) surface ordering and bulklike vertical stacking (O-Ce-O) down to a single ceria monolayer representing the oxide-metal interface. Scanning tunneling microscopy (STM) reveals marked differences in strain buildup and the structure of oxygen vacancies in this first ceria monolayer compared to thicker ceria layers on Cu(111). Ab-initio calculations allow us to trace back the distinct properties of the first ceria monolayer to pronounced finite size effects when the limiting thickness of the oxide monolayer and the proximity of metal substrate cause significant rearrangement of charges and oxygen vacancies compared to thicker and/or bulk ceria

Cationic surface reconstructions on cerium oxide nanocrystals: An aberration-corrected HRTEM study

Instabilities of nanoscale ceria surface facets are examined on the atomic level. The electron beam and its induced atom migration are proposed as a readily available probe to emulate and quantify functional surface activity, which is crucial for, for example, catalytic performance. In situ phase contrast high-resolution transmission electron microscopy with spherical aberration correction is shown to be the ideal tool to analyze cationic reconstruction. Hydrothermally prepared ceria nanoparticles with particularly enhanced {100} surface exposure are explored. Experimental analysis of cationic reconstruction is supported by molecular dynamics simulations where the Madelung energy is shown to be directly related to the binding energy, which enables one to generate a visual representation of the distribution of "reactive" surface oxygen. © 2011 American Chemical Society

Stabilization Principles for Polar Surfaces of ZnO

Lauritsen JV, Porsgaard S, Rasmussen MK, et al. Stabilization Principles for Polar Surfaces of ZnO. ACS Nano. 2011;5(7):5987-5994