CAREER: Revealing spin-state-dependent reactivity in open-shell single atom catalysts with systematically-improvable computational tools

该项目的重点是将天然气中的碳氢化合物选择性地转化为制造各种化学品和燃料的有价值的中间体产品。为此，该项目将研究一类被称为单原子催化剂（SACs）的新型催化材料，特别是通过开发有助于发现和设计SACs的计算建模工具。由此产生的基本理解将使我们能够合理地设计出强大而稳定的sac，用于有针对性的具有挑战性的化学转化，从而为化学和石油工业提供新的催化剂，以保持我们国家在化学和能源领域的竞争力。这些研究进展将构成基于任务的研讨会活动的基础，向波士顿地区6-12年级的学生教授催化和计算，提高对STEM的兴趣。单原子催化剂（SACs）是一种新兴的催化材料，有望将多相催化剂的可扩展性与均相催化剂的活性、选择性和原子经济性结合起来，但对SACs的反应性了解甚少。短寿命、亚纳米级的SAC活性位点挑战了实验光谱技术的分辨率，使得计算建模对于理解SAC催化剂的机理至关重要。该项目将通过系统改进的计算模型，促进对SAC结构如何赋予关键转化（即选择性部分碳氢化合物氧化）独特反应性的理解。尽管SAC在选择性但可扩展的催化剂中被视为一种新范式，但使SAC对基本催化转化具有反应性的特征也使得传统的计算催化工具（即半局部密度泛函数理论或DFT）不适合预测性SAC研究。该项目将确定并实施所需的系统进展，超越半局部DFT，用于预测配体场影响的自旋和氧化态如何在SAC活性位点改变量子限制金属的反应性。对单原子催化剂的基本认识将通过三个目标来实现：1)量化选择性转化中SAC的自旋态依赖的反应性；2)了解支持层身份和活性位点配置/无序如何影响SAC的电子结构和反应性；3)开发描述子来预测和优化SAC的活性和稳定性。这将使sac能够根据选择性、活性和可扩展性进行定制，以解决催化部分烷烃氧化的“圣杯”挑战。它将彻底改革研究独特SAC电子结构特性的仿真方法，既提供准确的预测，又在合理的SAC设计中纳入无序效应。在地球资源丰富、原子经济利用金属的条件下，发展具有工业规模的sac将对环境产生深远的影响。这些研究进展将被整合到每年两次的研讨会中，向6-12年级的学生教授催化和计算，提高他们对STEM的兴趣。研讨会将通过3D模型介绍催化和键合的概念，学生们将在一个任务游戏中设计催化剂，该游戏改编自作为该项目一部分开发的软件。课程将在研讨会前后通过小测验进行评估和改进。在PI的网站和麻省理工学院开放课程上发布的课堂教学材料和网络教程将扩大教育计划的影响范围。该计划将通过沉浸式和研究衍生工具提高对STEM的兴趣，从而造福社会。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The project focuses on selective chemical conversion of hydrocarbons found in natural gas to products of value as intermediates in the manufacture of a wide range of chemicals and fuels. To that end, the project will investigate a new class of catalytic materials known as single atom catalysts (SACs), specifically by developing computational modeling tools that will aid the discovery and design of SACs. The resulting fundamental understanding will enable rational design of robust and stable SACs for targeted challenging chemical transformations, thus providing the chemical and petroleum industries with new catalysts needed to maintain our Nation's competitiveness in the chemicals and energy sectors of the economy. These research advances will form the basis of quest-based workshop activities that teach catalysis and computation to Boston-area grade 6-12 students, advancing excitement about STEM. Single atom catalysts (SACs) are emergent catalytic materials that promise to unite the scalability of heterogeneous catalysts with the activity, selectivity, and atom-economy of homogeneous catalysts, but the reactivity of SACs is poorly understood. Short-lived, sub-nanoscale SAC active sites challenge the resolution of experimental spectroscopic techniques, making computational modeling essential to building understanding of the mechanism of SAC catalysts. The project will advance understanding of how SAC structure imparts unique reactivity for critical transformations (i.e., selective partial hydrocarbon oxidation) through systematically improvable computational modeling. Although SACs are poised as a new paradigm in selective but scalable catalysts, the very features that make SACs reactive for essential catalytic transformations also make conventional computational catalysis tools (i.e., semi-local density functional theory or DFT) ill suited to predictive SAC study. This project will identify and implement needed systematic advances beyond semi-local DFT for predictive modeling of how ligand-field-influenced spin- and oxidation-state of quantum-confined metals at SAC active sites alters reactivity. Advancement of fundamental understanding of single atom catalysts will be achieved through three aims: 1) quantifying spin state-dependent reactivity of SACs for selective transformations, 2) understanding how support identity and active site configuration/disorder influences electronic structure and reactivity of SACs, and 3) developing descriptors to predict and optimize SAC activity and stability. This will enable the tailoring of SACs for selectivity, activity, and scalability needed to address the "holy grail" challenge in catalysis of partial alkane oxidation. It will overhaul simulation methods for studying unique SAC electronic structure properties, both providing accurate predictions and incorporating disorder effects in rational SAC design. Development of SACs robust for the industrial scale with earth abundant, atom economical metal use will have a profound impact on the environment. The research advances will be integrated into outreach activities in a twice-yearly workshop that teaches catalysis and computation to grade 6-12 students, advancing excitement about STEM. The workshop will introduce catalysis and bonding concepts through 3D models, and students will design catalysts in a quest game adapted from software developed as part of this project. The program will be assessed and improved by quizzes before/after the workshop. Teaching materials for classroom instruction and web tutorials posted on the PI's website and MIT OpenCourseWare will amplify the reach of the education program. This program will benefit society by advancing excitement about STEM through immersive and research-derived tools.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.