Defect Chemistry of Metal Oxides for Catalytic Reactive Oxygen Species Generation

通过这一奖项，化学催化项目资助了内布拉斯加大学林肯分校的张金丽和奥马哈内布拉斯加大学的梅伟宁，用于研究某些工业上重要的催化剂是如何发挥作用的。该项目的具体重点是了解微小金属氧化物颗粒中的缺陷是如何导致它们具有催化剂功能的。正在研究的氧化物之一，一种被称为氧化铈的物质，被广泛用作汽车催化转化器的催化剂，作为石油精炼的关键部件，以及在各种化学制造应用中。尽管氧化铈在工业上有着广泛的用途和重要性，但其催化活性的机理仍不是很清楚。为了更详细地研究这一点，该小组正在制备表面有缺陷或缺陷的氧化铈小颗粒。这些小颗粒的制备方法也是如此，它们含有外来金属或掺杂剂，也被认为与它们的催化活性有关。这些精心准备的颗粒催化化学反应的能力被确定，然后与存在的缺陷和掺杂剂相关。该小组正在使用计算机建模，以更全面地了解催化过程中可能发生的反应。通过这种实验和理论相结合的方法，研究人员能够更全面地控制这些小颗粒的催化活性，并更充分地了解它们是如何发挥作用的。这项工作正在对工业和技术产生广泛的影响，并可能导致改进的催化剂，用于各种技术应用。通过本科生和高中生的参与，这项工作产生了进一步广泛的影响。甚至更年轻的学生也被纳入到这项工作中，通过为中学生和在家接受教育的学生提供创新的夏令营计划。这个项目的目的是加深对表面-亚表面缺陷相互作用对表面结合位化学活性的作用的基本理解，表面结合位参与了降维金属氧化物系统中的分子吸附。这些知识有望为环境和工业过程中可还原金属氧化物产生和湮灭活性氧物种(ROS)提供催化途径。水热法制备了不同形状、不同晶面、不同化学杂质含量的纳米CeO_2。这些颗粒与过氧化氢催化反应生成ROS的动力学正在测定中。通过对动力学数据的分析和DFT模拟，确定了亚表面缺陷对表面结合位上分子吸附能的影响，并确定了潜在的分子反应途径。

With this award, the Chemical Catalysis Program is funding Chin Li Cheung of the University of Nebraska at Lincoln and Wai-Ning Mei of the University of Nebraska at Omaha for research to investigate how certain industrially important catalysts function. The specific focus of this project seeks to understand how defects in tiny metal oxide particles lead to their ability to function as catalysts. One of oxides being studied, a substance known as cerium oxide, is used extensively as a catalyst in automobile catalytic converters, as a key component in petroleum refining, and in a wide variety of chemical manufacturing applications. Despite its widespread use and importance to industry, the mechanism for cerium oxide's catalytic activity is still not well understood. To investigate this in more detail, the group is preparing small particles of cerium oxide with imperfections, or defects, on their surfaces. These small particles are also being prepared in such a way that they contain foreign metals, or dopants, also thought to be related to their catalytic activity. The ability of these carefully prepared particles to catalyze chemical reactions is determined and, then, correlated with the defects and dopants that are present. The group is using computer modeling to more fully understand the reactions that may be taking place during catalysis. With this combined experimental and theoretical approach, the investigators are able to more completely control the catalytic activity of these small particles and more fully understand how they function. The work is having a broad impact on industry and technology, and may lead to improved catalysts for a wide variety of technological applications. The work is having a further broad impact through the engagement of students at both the undergraduate and high school level. Even younger students are being included in the work through an innovative summer camp program for middle school and home-schooled students. This project aims to develop a fundamental understanding of the role of surface-subsurface defect interactions on the chemical activity of surface binding sites that are involved in molecular adsorption in metal oxide systems of reduced dimension. Such knowledge is expected to yield catalytic pathways for reactive oxygen species (ROS) generation and annihilation with reducible metal oxide in the environment and in industrial processes. Ceria nanoparticles with different shapes, facets and chemical impurity content are being synthesized by hydrothermal methods. The kinetics of the catalytic reactions of these particles with hydrogen peroxide to generate ROS are being determined. Analysis of the kinetic data coupled with DFT modeling are used to identify the effect of subsurface defects on the molecular adsorption energies at the surface binding sites and to determine potential molecular reaction pathways.