Collaborative Research: Elucidation of the Role of Atomic Structures of CeO2(111) on the Nucleation and Growth of Metal Clusters through in situ STM and Theory

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With support from the Macromolecular, Supramolecular and Nanochemistry (MSN) Program in the Division of Chemistry, Jing Zhou of the University of Wyoming and Ye Xu of Louisiana State University are combining advanced chemical analysis tools and theoretical modeling to reveal atomic level details about how nano-clusters of nickel (Ni) and cobalt (Co) metals grow on well-defined cerium oxide (CeO2, ceria) single crystal surfaces. The growth of metals on oxide surfaces is of interest to a number of technological applications including heterogeneous catalysis, electronic devices, and gas sensing. Surface structures of CeO2 influence the physical and chemical properties of deposited metals, leading to unique applications such as active and robust catalysts, sensors, and electronic/magnetic materials. Drs. Zhou and Xu and their students are investigating the detailed role that ceria plays in controlling the nucleation, size, and structure of supported Ni and Co nano-clusters. Graduate, undergraduate, and high school students involved in this research will be prepared for future careers at the intersection of nanoscience, chemistry, materials science, and computational modeling.Active metals such as Ni and Co supported on reducible ceria can exhibit distinct chemical behavior owing to the unique redox properties and oxygen storage capacity of ceria as well as strong metal-support interaction. Surface structures including oxygen vacancies, step edges, and terraces on CeO2 can affect the oxidation state, size, structure, distribution, and density of Ni and Co ad-clusters and alter their reactivity and stability. The project involves preparing model CeO2 single crystal surfaces with controlled structures, using scanning tunneling microscopy (STM) with in situ characterization capabilities to examine the deposition of Ni and Co metals and the growth mechanisms of Ni and Co nano-clusters on the CeO2 surface with respect to specific support structures, and using theoretical methods to aid and enhance the interpretation of the experimental STM results. These studies are expected to allow for the identification of the nucleation sites for Ni and Co metals and the factors that control the growth and properties of these metals on ceria. The knowledge gained on this project should help provide strategies for designing nano-sized metals with tailored structures and functionalities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.