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The Structure, Oxidation States, and Energetics of Co Nanoparticles on CeO2(111): An STM and DFT Study


Abstract Co nanoparticles (NPs) dispersed on ceria have been widely studied as active catalytic materials for many industrially relevant reactions. The detailed nature of such particles and the factors affecting their interaction with ceria remain to be better understood. In this study, a very low coverage (∼0.02 ML) of Co is deposited on a model CeO2(111) thin-film surface and is examined using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). The Co NPs that nucleate on terrace sites grow with coverage in this range to a maximum size of ca. 40 Co atoms, with an average diameter and height of 16.1 and 1.1 Å, respectively. Global minimization of the structures of Co NPs consisting of up to 23 Co atoms on CeO2(111) is performed based on the minima hopping algorithm and density functional theory (DFT) calculations, and the energetic and chemical properties of the resulting NPs are analyzed. While the theoretical findings are consistent with the STM observations on the strong Co-ceria interactions and the prevalence of oxidic Co species, some notable discrepancies are identified, including inconsistent aspect ratios and the existence of a low oxidation state Coδ+ species. The combined experimental and theoretical findings provide new insights into Co NPs formed on ceria and identify areas requiring further investigation.
Authors Md. Saeedur Rahman ORCID , Nishan Paudyal University of WyomingORCID , Linze Du Hill University of WyomingORCID , Jing Zhou University of WyomingORCID , Ye Xu ORCID
Journal Info American Chemical Society | The Journal of Physical Chemistry C , vol: 128 , iss: 43 , pages: 18430 - 18441
Publication Date 8/28/2024
ISSN 1932-7447
TypeKeyword Image article
Open Access hybrid Hybrid Access
DOI https://doi.org/10.1021/acs.jpcc.4c03911
KeywordsKeyword Image Energetics (Score: 0.8457769)