Atomically Dispersed Pd–O Species on CeO<sub>2</sub>(111) as Highly Active Sites for Low-Temperature CO Oxidation

Ceria-supported Pd\nis a promising heterogeneous catalyst for CO\noxidation relevant to environmental cleanup reactions. Pd loaded onto\na nanorod form of ceria exposing predominantly (111) facets is already\nactive at 50 °C. Here we report a combination of CO-FTIR spectroscopy\nand theoretical calculations that allows assigning different forms\nof Pd on the CeO₂(111) surface during reaction conditions.\nSingle Pd atoms stabilized in the form of PdO and PdO₂ in\na CO/O₂ atmosphere participate in a catalytic cycle involving\nvery low activation barriers for CO oxidation. The presence of single\nPd atoms on the Pd/CeO₂-nanorod, corroborated by aberration-corrected\nTEM and CO-FTIR spectroscopy, is considered pivotal to its high CO\noxidation activity.