Connecting Kinetics and Mechanisms to Surface Structures on Highly-Oxidized Metal Surfaces in Heterogeneous Catalysis

在化学部化学催化项目的资助下，芝加哥洛约拉大学（LUC）的Dan Killelea将探索在非均相催化氧化反应中存在的活性物质，并将探索它们的能量学，以促进对催化活性金属氧化表面化学的理解。金属表面上的非均相催化氧化反应表面上看起来很简单，但由于表面的非均相性，微妙的细节可能占主导地位。这些关键的细节往往是模糊的，使得精确的原子水平描述难以捉摸，甚至像CO氧化成CO2这样的“简单”反应。阐明这些关于多相催化反应的原子级细节，预计将有助于在利用稀缺资源方面取得进展，并减少对环境有害的副产物的产生。结合表面化学方面，该项目将通过各种外展努力为芝加哥公立学校（CPS）中代表性不足的社会经济群体提供科学研究机会：高中实验室，参观LUC设施，以及暑期实习计划。额外的参与和推广工作将包括与当地大学的招生顾问举办CPS学生会议，以及前往阿贡国家实验室。通过这些努力，来自经济弱势社区的高中生将接触到科学，并了解新的教育机会和职业。在这个奖项下，芝加哥洛约拉大学的Dan Killelea和他的团队正在努力揭示观察到的表面结构与反应动力学和多相催化系统机制之间的联系。铑金属表面是后过渡金属的代表，用特定的、特征良好的含氧相可重复制备。缺陷密度和几何形状对表面氧化和化学的影响将使用弯曲的Rh（111）晶体进行系统的探索。扫描隧道显微镜（STM）成像的结构数据将使用密度泛函理论（DFT）的输入进行解释，DFT也将计算Osub的能量学。获得的数据将与辅助的表面科学测量相补充。在洛约拉收集的反应性和结构测量将确定表面状态和进一步研究CO氧化的条件。这些实验将在莱顿（荷兰）和Göttingen（德国）进行，采用反应性分子束散射和速度分辨探测。该项目的研究结果有望通过提供有关多相催化氧化反应的动力学和机制的急需的基础信息来推进催化表面化学，并揭示地下氧在这些工业相关反应中的重要性。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 funding from the Chemical Catalysis program of the Chemistry Division, Dan Killelea of Loyola University of Chicago (LUC) will explore the reactive species present during heterogeneously catalyzed oxidation reactions and will probe their energetics to advance understanding of the oxidative surface chemistry of catalytically active metals. Heterogeneously catalyzed oxidation reactions on metal surfaces seem superficially straightforward, yet subtle details may dominate because of the heterogeneity of the surfaces. These key details are often obscured, rendering accurate atomic-level descriptions elusive for even a ‘simple’ reaction like CO oxidation to CO2. Illuminating these atomic-level details about heterogeneously catalyzed reactions is expected to contribute to advances in the utilization of scarce resources and to a reduction in the generation of environmentally harmful byproducts. In conjunction with the surface chemistry aspect, this project will offer scientific research opportunities to under-represented socioeconomic groups in the Chicago Public Schools (CPS) through various outreach efforts: the high school lab, tours of LUC facilities, and a summer internship program. Additional engagement and outreach efforts will include hosting CPS student meetings with admissions counselors from local universities and trips to Argonne National Laboratory. Through these efforts, high school students from economically disadvantaged neighborhoods will gain exposure to science and learn about new educational opportunities and careers.Under this award, Dan Killelea of Loyola University, Chicago and his team are working to uncover the connection between observed surface structures and reaction kinetics and mechanism for heterogeneous catalysis systems. Rhodium metal surfaces, which are representative of the late-transition metals, are reproducibly prepared with specific, well-characterized oxygenaceous phases. The effects of defect density and geometry on surface oxidation and chemistry will be systematically explored using a curved Rh(111) crystal. Structural data from scanning tunneling microscopy(STM)-imaging will be interpreted using input from density functional theory (DFT), which will also calculate the energetics of Osub. The data obtained will be complemented with ancillary surface science measurements. The reactivity and structural measurements collected at Loyola will identify the surface states and conditions for further study of CO oxidation. These experiments will be conducted in Leiden (Netherlands) and Göttingen (Germany) with the reactive molecular-beam scattering with velocity resolved detection. The results of this project are expected to advance catalytic surface chemistry by providing much-needed fundamental information about the kinetics and mechanisms of heterogeneously catalyzed oxidation reactions and reveal the importance of subsurface oxygen in these industrially relevant reactions.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.