Collaborative Research: Directly probing the local coordination, charge state and stability of single atom catalysts – Critical insights from advanced TEM for promoting stability

合作研究：直接探测单原子催化剂的局域配位、电荷状态和稳定性 — 来自先进 TEM 的关键见解，以促进稳定性

• 批准号: 2031512
• 负责人: Phillip Christopher
• 金额: $ 18.4万
• 依托单位: University of California-Santa Barbara
• 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: 2020-11-15 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2031512&HistoricalAwards=false
• 关键词: Collaborative; Research; Directly; probing; local

The drive for atom-efficient catalysts with carefully controlled properties has motivated the development of single atom catalysts (SACs), where single precious metal atoms are stabilized on high-surface-area supports. SACs exhibit unique and potentially useful characteristics for chemical processes ranging from automotive catalysis to electrocatalysis. However, information about the structure of the metal binding site on the support and its stability under reaction conditions is sparse. This is due to a lack of insights into the uniformity of metal species and their mobility, which are challenging to assess from sample-averaged measurements. The investigators will overcome these limitations to obtain atomic-scale and quantitative insights into the working state of SACs by coupling state-of-the-art atomic resolution transmission electron microscopy and spectroscopy with careful catalyst synthesis and sample averaged analyses. The study will focus on the design of catalysts that utilize expensive and scarce noble metals more effectively, thus opening the door to more efficient and economical chemical manufacturing and environmental remediation technologies. The research is integrated with education and outreach activities to attract diverse junior scientists, including women and underrepresented minority groups, and train future leaders to address critical societal challenges.The project leverages unique electron microscopy facilities at the University of California-Irvine (UCI) with state-of-the-art catalyst synthesis and spectroscopic characterization capabilities at the University of California-Santa Barbara (UCSB). The central objectives of the research are to utilize advanced ex situ and in situ aberration-corrected scanning transmission electron microscopy and associated electron energy loss spectroscopy to probe the local coordination, metal charge state, and stability of SACs and correlate these properties to spectroscopic analysis by in situ infrared spectroscopy. The study of SACs benefits significantly from in situ sub-angstrom resolution imaging, as this provides site-specific information needed to interpret spectroscopic data from sample averaged measurements. This project focuses on Pt, Rh, and Au SACs on alumina (modified by atomically-dispersed Re and W), titania, and ceria which present variations in metal oxidation-state, support-reducibility, and available bindings sites. Detailed characterization of these systems enables the design of new catalysts with tuned reactivity and stability for catalytic processes such as CO oxidation, NO reduction, and alkene hydroformylation. The integration of the research with education and training of students allows the results from this project to be disseminated to the diverse student populations of UCI and UCSB during coursework and internships for undergraduate students, as well as to high school students from diverse backgrounds through summer school programs, which will promote their interest in scientific research and education.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.

对具有仔细控制的性质的原子效率催化剂的驱动已经推动了单原子催化剂（SAC）的开发，其中单个贵金属原子稳定在高表面积载体上。SAC表现出独特的和潜在的有用的特性，从汽车催化到电催化的化学过程。 然而，关于支持物上的金属结合位点的结构及其在反应条件下的稳定性的信息很少。这是由于缺乏对金属物质的均匀性及其流动性的了解，这对于从样品平均测量值进行评估具有挑战性。研究人员将克服这些限制，通过将最先进的原子分辨率透射电子显微镜和光谱学与仔细的催化剂合成和样品平均分析相结合，获得对SAC工作状态的原子尺度和定量见解。该研究将侧重于设计更有效地利用昂贵和稀缺贵金属的催化剂，从而为更有效和更经济的化学制造和环境修复技术打开大门。该研究与教育和推广活动相结合，以吸引不同的年轻科学家，包括妇女和代表性不足的少数群体，并培养未来的领导者，以应对关键的社会挑战。该项目利用加州大学欧文分校（UCI）独特的电子显微镜设施，以及加州大学圣巴巴拉分校（UCSB）最先进的催化剂合成和光谱表征能力。 该研究的中心目标是利用先进的非原位和原位像差校正扫描透射电子显微镜和相关的电子能量损失谱来探测本地协调，金属电荷状态和稳定性的SAC和相关的这些属性的光谱分析原位红外光谱。SACs的研究受益显着从原位亚埃分辨率成像，因为这提供了特定网站的信息需要解释光谱数据从样品平均测量。该项目的重点是Pt，Rh，和Au SAC的氧化铝（改性原子分散的Re和W），二氧化钛和氧化铈，目前的变化，在金属氧化状态，支持还原，和可用的绑定网站。这些系统的详细表征使得能够设计具有调谐的反应性和稳定性的新催化剂用于催化过程，例如CO氧化、NO还原和烯烃加氢。研究与学生的教育和培训相结合，使该项目的结果能够在本科生的课程和实习期间传播给UCI和UCSB的不同学生群体，以及通过暑期学校课程传播给来自不同背景的高中生，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的学术价值和更广泛的影响审查标准。