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，怀俄明州大学的Jing Zhou和路易斯安那州州立大学的Ye Xu正在将先进的化学分析工具和理论建模相结合，以揭示镍（Ni）和钴（Co）金属纳米簇如何在定义明确的氧化铈（CeO 2，二氧化铈）单晶表面上生长的原子水平细节。金属在氧化物表面上的生长对许多技术应用感兴趣，包括多相催化、电子器件和气体传感。CeO 2的表面结构会影响沉积金属的物理和化学性质，从而导致独特的应用，如活性和耐用的催化剂，传感器和电子/磁性材料。Zhou和Xu博士以及他们的学生正在研究二氧化铈在控制支撑的Ni和Co纳米簇的成核、尺寸和结构方面所起的详细作用。参与这项研究的研究生、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，活性金属如Ni和Co负载在可还原氧化铈上可以表现出独特的化学行为。表面结构，包括氧空位，台阶边缘，和CeO 2上的梯田可以影响的氧化态，尺寸，结构，分布和密度的Ni和Co的ad-集群，并改变它们的反应性和稳定性。该项目涉及准备模型CeO 2单晶表面与控制结构，使用扫描隧道显微镜（STM）与原位表征能力，以检查沉积的Ni和Co金属和生长机制的Ni和Co纳米团簇的CeO 2表面上的特定支持结构，并使用理论方法，以帮助和提高解释的实验STM结果。这些研究预计将允许镍和钴金属的成核位点的识别和控制这些金属的生长和性质的因素，二氧化铈。该项目获得的知识应有助于为设计具有定制结构和功能的纳米尺寸金属提供策略。该奖项反映了NSF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.