Surface and Interface Free Energies of Epitaxial Nanocrystals

外延纳米晶体的表面和界面自由能

• 批准号: 1006077
• 负责人: Jian-Min Zuo
• 金额: $ 58万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006077&HistoricalAwards=false
• 关键词: Surface; Interface; Free; Energies; Epitaxial

TECHNICAL SUMMARY: It is proposed to investigate the surface and interfacial energies of epitaxial metal nanocrystals and correlate them with their atomic structure. Epitaxial Au nanocrystals on TiO2 will be used as a model system for study. Epitaxy provides interfacial uniformity and also provides better control of nanocrystalline shapes. TiO2 is selected because of its function as a reducible oxide for catalyst support and the extensive knowledge about its surfaces in the literature. The Au nanocrystals will be synthesized using the deposition and annealing technique developed in the PI's group. Aberration-corrected scanning transmission electron microscopy and transmission electron microscopy will be used to characterize the structure of the Au nanocrystals and their interfaces. The structural data will be used to measure the surface and interfacial energies of the Au nanocrystals as a function of size. On the theoretical front, the interfacial and triple-line geometries, the local electronic density of states, and the energy of Au on TiO2 for different epitaxies will be computed from first-principles. The combination of experiment with theory is expected to lead to significantly improved understanding of the structure and property relationships in nanocrystal surfaces and interfaces.NON-TECHNICAL SUMMARY: Substantial parts of materials technology, major components of chemical industry, and exciting new developments in medical diagnostics and treatments rely on the properties of supported metallic nanoparticles. The unusual functions of metallic nanoparticles come from the synergistic interactions of surfaces and interfaces of nanoparticles and their support. However, modern studies have largely avoided the complexity of supported nanoparticles; nanoparticles are too small for experimental characterization and too big for rigorous theoretical investigations. This project is to study nanocrystal surfaces and interfaces by taking advantage of the recent progress in atomic resolution imaging using aberration-correction in transmission electron microscopy and combining it with nanocrystal synthesis and theory. The research will be integrated with outreach efforts, including high school visits and undergraduate education. Results from this research project will be incorporated in the web-based educational materials for teaching students about atomic structure and diffraction, infrastructure for which is already in place (see http://emaps.mrl.uiuc.edu/ or google webemaps). This particular website is now listed as one of the best web resources for learning electron diffraction and electron diffraction pattern indexing in the standard transmission electron microscopy workplace.

技术摘要：建议研究外延金属纳米晶体的表面和界面能，并将它们与其原子结构相关联。 TiO2 上的外延金纳米晶体将用作研究的模型系统。外延提供了界面均匀性，并且还提供了对纳米晶体形状的更好控制。选择 TiO2 是因为它作为催化剂载体的可还原氧化物的功能以及文献中关于其表面的广泛知识。 Au 纳米晶体将使用 PI 小组开发的沉积和退火技术来合成。像差校正扫描透射电子显微镜和透射电子显微镜将用于表征金纳米晶体及其界面的结构。结构数据将用于测量金纳米晶体的表面和界面能作为尺寸的函数。 在理论方面，将根据第一原理计算不同外延层的界面和三线几何结构、局域电子态密度以及 TiO2 上 Au 的能量。实验与理论的结合有望显着提高对纳米晶体表面和界面的结构和性质关系的理解。非技术摘要：材料技术的实质部分、化学工业的主要组成部分以及医疗诊断领域令人兴奋的新发展和治疗依赖于负载的金属纳米颗粒的特性。金属纳米粒子的不寻常功能来自纳米粒子表面和界面及其载体的协同相互作用。然而，现代研究很大程度上避免了负载纳米颗粒的复杂性。纳米粒子对于实验表征来说太小，对于严格的理论研究来说又太大。该项目旨在利用透射电子显微镜中像差校正的原子分辨率成像的最新进展，并将其与纳米晶体合成和理论相结合，研究纳米晶体表面和界面。该研究将与推广工作相结合，包括高中访问和本科教育。该研究项目的结果将被纳入基于网络的教育材料中，用于向学生讲授原子结构和衍射，其基础设施已经就位（参见http://emaps.mrl.uiuc.edu/或google webemaps）。该特定网站现已被列为在标准透射电子显微镜工作场所学习电子衍射和电子衍射图案索引的最佳网络资源之一。