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

在化学系大分子、超分子和纳米化学（MSN）项目的支持下，怀俄明大学的周静（Jing Zhou）和路易斯安那州立大学的徐晔（Ye Xu）结合先进的化学分析工具和理论建模，揭示了镍（Ni）和钴（Co）金属纳米团簇如何在明确定义的氧化铈（CeO2, ceria）单晶表面上生长的原子水平细节。金属在氧化物表面的生长引起了许多技术应用的兴趣，包括多相催化、电子器件和气体传感。CeO2的表面结构影响沉积金属的物理和化学性质，导致独特的应用，如活性和坚固的催化剂，传感器和电子/磁性材料。Drs。周、徐和他们的学生正在研究铈在控制Ni和Co纳米团簇的成核、尺寸和结构方面所起的详细作用。参与本研究的研究生、本科生和高中生将为未来在纳米科学、化学、材料科学和计算建模交叉领域的职业生涯做好准备。由于氧化铈独特的氧化还原性能和储氧能力以及强的金属-载体相互作用，氧化铈上负载的Ni和Co等活性金属表现出不同的化学行为。CeO2表面的氧空位、台阶边缘和阶地等结构会影响Ni和Co簇的氧化态、大小、结构、分布和密度，并改变它们的反应性和稳定性。该项目包括制备具有可控结构的CeO2模型单晶表面，使用具有原位表征能力的扫描隧道显微镜（STM）来检查Ni和Co金属的沉积以及相对于特定支撑结构的Ni和Co纳米团簇在CeO2表面上的生长机制，并使用理论方法来帮助和增强对实验STM结果的解释。这些研究有望确定镍和钴金属的成核位置以及控制这些金属在二氧化铈上生长和性质的因素。从这个项目中获得的知识应该有助于为设计具有定制结构和功能的纳米级金属提供策略。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.