Imaging of Element-Specific 3D Distribution Dynamics in Working Bimetallic Catalysts by in-situ Anomalous Small-Angle X-Ray Scattering

通过原位反常小角 X 射线散射对工作双金属催化剂中元素特异性 3D 分布动力学进行成像

基本信息

批准号：
2002960
负责人：
Yugang Sun
金额：
$ 37.64万
依托单位：
Temple University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2024-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2002960&HistoricalAwards=false
关键词：
Imaging Element Specific 3D Distribution

项目摘要

With this award, the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry is supporting Dr. Yugang Sun at Temple University to combine computation and X-ray methods to develop a rapid chemical imaging tool that maps out the location of individual metals. Utilizing this tool, he and his team seek to glean a real-time, three-dimensional "picture" of metals in nanoscale metal catalyst particles on an atom-by-atom basis. Many alternative fuel sources are derived from catalytic processes based on such metal nanoparticles. New measurement methods that reveal information about the arrangement and location of metal atoms in the catalyst and how atom location and arrangement change during the chemical conversion process have great potential to enhance our fundamental understanding of catalysis in these systems. This novel solution to a long-standing challenge may well provide new insights into the how atomic-level structure affects behavior of nanometer-sized catalysts, while also holding potential to understand how the chemical behavior of other nanoparticles is influenced by their environment over time. These new measurement methods are anticipated to lead to significant impacts on chemical reactions used in industry, ranging from those that produce chemical or pharmaceutical building blocks to those that produce alternative fuels. The use of the state-of-the-art large-scale synchrotron X-ray facilities at national laboratories trains the students to become specialists in a significant area that is underrepresented in the typical chemist's skill set. More broadly, the research educates a highly diverse group of students about the use of cutting-edge chemical measurement tools to address important scientific problems, with an emphasis on workforce development in the field of alternative fuels. Dr. Sun and his team also integrate research outcomes into the Philadelphia community and beyond through a range of education and outreach programs to students and teachers at local urban/high-need schools and Community Colleges, as well as students participating in a National Science Foundation undergraduate research program and the Temple University TUteach initiative.In this project, Dr. Sun and his research team integrate small-angle X-ray scattering (SAXS) measurements with ab initio modeling and calculation results to construct models of the three-dimensional (3D) geometry of uniform nanoparticles of well-defined chemical composition. This project is developing this imaging protocol to enable the study of the element-specific evolution of 3D atom distributions in bimetallic nanoparticle catalysts under working conditions. Such endeavors require two consecutive steps. First, the element-specific SAXS patterns are deconvoluted from the highly convoluted anomalous small-angle X-ray scattering (ASAXS) of bimetallic nanoparticles based on penalized regression methods. Second, an imaging protocol is being developed to determine element-specific 3D images of the composition distribution in bimetallic nanoparticles through ab initio modeling of the deconvoluted element-specific SAXS patterns. The ASAXS imaging protocol may then be applicable to in-situ ASAXS imaging through its use with working reactors, allowing for the study of the time-resolved evolution of element-specific 3D distributions of metals in bimetallic catalysts in operando.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.

凭借该奖项，化学系的化学测量和成像 (CMI) 项目正在支持天普大学的 Yugang Sun 博士将计算和 X 射线方法结合起来，开发一种快速化学成像工具，可绘制出单个金属的位置。利用这一工具，他和他的团队试图在逐个原子的基础上收集纳米级金属催化剂颗粒中金属的实时三维“图片”。许多替代燃料来源源自基于此类金属纳米颗粒的催化过程。新的测量方法揭示了催化剂中金属原子的排列和位置以及化学转化过程中原子位置和排列如何变化的信息，具有巨大的潜力，可以增强我们对这些系统中催化作用的基本理解。这种针对长期挑战的新颖解决方案很可能为原子级结构如何影响纳米尺寸催化剂的行为提供新的见解，同时也有可能了解其他纳米粒子的化学行为如何随时间变化而受到其环境的影响。这些新的测量方法预计将对工业中使用的化学反应产生重大影响，从生产化学或制药构件的化学反应到生产替代燃料的化学反应。使用国家实验室最先进的大型同步加速器 X 射线设备，可以将学生培养成为典型化学家技能中代表性不足的重要领域的专家。更广泛地说，该研究教育高度多样化的学生群体如何使用尖端化学测量工具来解决重要的科学问题，重点是替代燃料领域的劳动力发展。孙博士和他的团队还通过一系列教育和推广计划，向当地城市/高需求学校和社区学院的学生和教师以及参与国家科学基金会的学生，将研究成果融入费城社区及其他地区。本科生研究计划和天普大学 TUteach 计划。在该项目中，孙博士和他的研究团队将小角 X 射线散射 (SAXS) 测量与从头建模和计算结果相结合，构建三维 (3D) 模型）均匀纳米粒子的几何形状具有明确的化学成分。该项目正在开发这种成像协议，以便能够研究工作条件下双金属纳米颗粒催化剂中 3D 原子分布的元素特定演化。这种努力需要两个连续的步骤。首先，基于惩罚回归方法，从双金属纳米粒子的高度卷积异常小角度 X 射线散射 (ASAXS) 中对元素特定的 SAXS 图案进行解卷积。其次，正在开发一种成像协议，通过解卷积元素特定 SAXS 图案的从头建模来确定双金属纳米粒子中成分分布的元素特定 3D 图像。然后，通过与工作反应器一起使用，ASAXS 成像协议可适用于原位 ASAXS 成像，从而可以研究双金属催化剂中金属元素特定 3D 分布的时间分辨演化。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。