Understanding the restructuring of model metal catalysts in reactant gases

过渡金属在从化学和能源生产到环境修复的各种应用中扮演着关键的催化剂角色。充分的证据表明，催化剂的结构在使用过程中并没有保持不变。相反，由于金属原子的重新排列以形成新的结构，发生了实质性和重要的重组。这种重组对催化性能有重大影响，有时是有益的，有时是无益的。目前，科学家们还不清楚这种重组是如何在原子尺度上发生的，或者在类似于催化过程中使用的条件下发生的。在NSF化学催化计划的资助下，这项研究提供了对相关气体压力和反应温度下这种化学的基本理解。它是由堪萨斯大学的富兰克林·陶博士和加州大学洛杉矶分校的菲利普·索特博士进行的计算建模相结合的尖端实验。陶博士和Sautet博士正在将这种理论建模和实验工作融入到高中、本科生和研究生的教育和培训中。还为公立高中生的实验室提供暑期研究实习机会。在化学系化学催化项目的资助下，堪萨斯大学的陶博士和加州大学洛杉矶分校的Sautet博士正在将先进的原位/操纵性表征和基于第一原理的建模相结合，以加深对金属催化剂重组过程的基本理解。这项研究比较了几种金属(铂、钯、镍、钴、铜)在一氧化碳和其他反应物的压力下。实验方法包括高压扫描隧道显微镜(HP-STM)和操作室压X射线光电子能谱。这些对表面敏感的表面技术能够揭示气体压力下金属的表面化学和结构，并提供机制的初步全球视图，并确定全球动力学速率。理论建模带来了对原子论基本步骤及其能量的理解。它还提供了动力学结果，并与实验测量进行了比较，从而验证了该方法。由于计算需要大系统，因此能量是通过使用先前从密度泛函理论数据库训练的准确的高维神经网络势来获得的。以铂和铜表面的水-气变换反应为例，探讨了重构对催化反应的影响。陶博士和Sautet博士正在开发一项推广计划，重点是向高中生介绍催化研究模型和本科生培训。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Transition metals play key roles as catalysts in applications ranging from chemical and energy production to environmental remediation. Ample evidence indicates that catalyst structures do not remain unchanged during use. Instead, substantial and important restructuring occurs due to rearrangement of the metal atoms to make new structures. This restructuring has major consequences on catalytic properties, sometimes beneficial and sometimes not. Currently, scientists do not understand how the restructuring occurs at the atomic scale or under conditions similar to those used during catalysis. With funding from the NSF Chemical Catalysis Program, this research is providing a fundamental understanding of this chemistry under relevant gas pressures and reaction temperatures. It is being performed with a combination of cutting edge experiments by Dr. Franklin Tao from University of Kansas and computational modeling by Dr. Philippe Sautet from University of California Los Angeles. Drs. Tao and Sautet are incorporating this theoretical modeling and experimental work into the education and training of high school, undergraduate, and graduate students. Summer research internships for public high school students in their laboratories are also being provided. With funding from the Chemical Catalysis Program of the Division of Chemistry, Dr. Tao of the University of Kansas and Dr. Sautet from UCLA are combining advanced in situ/operando characterization and first principle based modelling to develop a fundamental understanding of the metal catalyst restructuring process. The research compares several metals (Pt, Pd, Ni, Co, Cu) under a pressure of carbon monoxide and other reactants. The experimental methods include high pressure scanning tunneling microscopy (HP-STM) and operando Ambient Pressure X-ray Photoelectron Spectroscopy. These surface-sensitive surface techniques allow for uncovering surface chemistry and structure of metals under a pressure of gas and provide an initial global view of the mechanism and determine global kinetic rates. Theoretical modelling brings an understanding of the atomistic elementary steps and of their energies. It also provides kinetic results that are compared with experimental measurement, hence validating the approach. Since large systems are required for the calculation, energies are obtained by using an accurate high dimensional neural network potential, previously trained from a density functional theory database. The influence of restructuring on catalytic reaction is being explored with the example of the water-gas shift reaction on Pt and Cu surfaces. Drs. Tao and Sautet are developing an outreach program focused on introducing high-school students to model catalysis research and on undergraduate student training.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.