Catalytic Chemistry with Shape-Tuned Nanoparticles

在这个由化学部化学催化项目资助的项目中，中佛罗里达大学（UCF）的Beatriz Roldan Cuenya将合成具有统一尺寸（1-3纳米）、形状和结构的金属纳米颗粒（NPs），并研究它们的几何形状和催化性能之间的相关性。目标材料系统将包括由二氧化钛、钛酸锶、氧化铝和二氧化锆支撑的金、铂和钯NPs。将研究具有环境和经济重要性的反应，例如金和铂NPs上的一氧化碳氧化和水气转换反应以及钯NPs上的氧化亚氮（NOx）还原。了解催化剂的结构和功能之间的关系需要详细了解它们的三维原子构型以及在反应条件下可能发生的化学变化。为了解决现实世界催化剂的复杂性，将采取一种利用各种实验方法的协同方法。这些方法包括原位x射线吸收光谱、原子分辨扫描和环境透射电子显微镜、扫描隧道和原子力显微镜、x射线光电子能谱和漫反射傅里叶变换红外光谱。在原子水平上调整纳米材料的化学反应性是催化研究中最重要的挑战之一。为了实现这一难以实现的目标，必须对这些复杂系统的几何和电子结构有基本的了解。许多研究都致力于了解影响金属纳米颗粒催化性能的性质，如它们的大小、与载体的相互作用和氧化态。然而，纳米颗粒的形状对催化性能的影响尚不清楚。使分析复杂化的事实是，前面的参数不能独立考虑，因为NP大小以及支持将对最稳定的NP形状产生影响。此外，必须考虑NP催化剂的动态性质及其对环境的响应，因为NP催化剂的工作状态可能不是催化剂制备时的状态，而是适应特定反应条件的结构和/或化学异构体。所选择的模型反应在能源产生和环境修复领域具有广泛的应用，例如在涡轮机和汽车催化过程中减少NOx。该项目将支持UCF的博士生和K-12学生的研究工作，这些学生也将在布鲁克海文国家实验室和阿贡国家实验室的用户设施中接受培训。此外，首席研究员将通过她与奥兰多科学中心的合作，包括组织年度海报展览，题为“科学中的艺术，艺术中的科学”，使纳米科学领域的概念更接近公众。

In this project funded by the Chemical Catalysis Program of the Chemistry Division, Beatriz Roldan Cuenya of the University of Central Florida (UCF) will synthesize metal nanoparticles (NPs) with uniform sizes (1-3 nm), shapes, and structures and investigate the correlation between their geometrical shape and catalytic properties. Target material systems will include gold, platinum, and palladium NPs supported on titanium dioxide, strontium titanate, aluminum oxide, and zirconium dioxide. Reactions of environmental and economic importance such as carbon monoxide oxidation and the water-gas-shift reaction over gold and platinum NPs and nitrous oxide (NOx) reduction over palladium NPs will be investigated. Understanding the relationship between the structure and function of catalysts requires detailed information about their three-dimensional atomic configurations as well as possible chemical changes occurring under reaction conditions. To address the complexity of real-world catalysts, a synergistic approach taking advantage of a variety of experimental methods will be undertaken. These methods include in-situ X-ray absorption spectroscopy, atomically-resolved scanning and environmental transmission electron microscopy, scanning tunneling and atomic force microscopy, X-ray photoelectron spectroscopy and diffuse reflectance Fourier transform infrared spectroscopy. Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in catalysis research. To achieve this elusive goal, fundamental understanding of the geometric and electronic structure of these complex systems must be obtained. Numerous studies have been devoted to understanding the properties that affect the catalytic performance of metal nanoparticles such as their size, interaction with the support, and oxidation state. The role played by the nanoparticle shape on catalytic performance is, however, less understood. Complicating the analysis is the fact that the former parameters cannot be considered independently, since the NP size as well as the support will have an impact on the most stable NP shapes. In addition, the dynamic nature of the NP catalysts and their response to the environment must be taken into consideration, since the working state of a NP catalyst might not be the state in which the catalyst was prepared, but rather a structural and/or chemical isomer that adapted to the particular reaction conditions. The selected model reactions have broad applications in the fields of energy generation and environmental remediation, as for example NOx reduction in turbines and automotive catalytic processes. This project will support the research efforts of doctoral students and K-12 students at UCF, which will also be trained at the user facilities of Brookhaven National Laboratory and Argonne National Laboratory. Furthermore, the principal investigator will bring concepts related to the field of nanoscience closer to the general public via her involvement with the Orlando Science Center, including the organization of an annual poster exhibit entitled "Art in Science, Science in Art".