Predictive Design and Scalable Synthesis of New Multimetallic Nanoparticles with Enhanced Surface Reactivity

这是两组教授之间的一个综合和计算研究项目。Simon M. Humphrey和Graeme Henkelman是德克萨斯大学奥斯汀分校的研究人员，他们的研究重点是新型纳米催化剂材料的制备和研究。催化剂减少了大规模化学过程中使用的总能量，包括燃料、聚合物和纺织品的合成、药物以及环境污染物的修复。催化剂还可以减少产生的废物副产物的数量。目前使用的大多数催化剂都是基于贵金属的，不幸的是，贵金属既稀缺又昂贵。因此，找到制备现代催化剂的方法是至关重要的，这种催化剂可以使用较少的总金属，同时保持其催化性能。在化学系大分子、超分子和纳米化学项目的支持下，该项目通过研究金属纳米颗粒催化剂的合成和性能来直接解决这些问题，金属纳米颗粒催化剂每个实体只包含几千个原子；与大块金属相比，纳米颗粒具有吸引力，因为它们表现出优越的反应性，并且与体积相比具有非常大的表面积。该项目还研究了使用可扩展和环境可持续的合成方法，如微波加热，以制备由以前未研究过的贵金属混合物组成的新型纳米颗粒催化剂。这些新催化剂的基本性质是通过实验和理论（计算）方法来评估的，以便了解其组成与实际化学反应中性能改进的关系。最终目标是应用实验和计算专业知识来预测新的催化剂组合物，这些组合物应该具有给定工业过程的最佳性能。该项目还通过与一个创新的新的本科教育计划相结合而得到显著加强，该计划被称为奥斯汀国际框架，在该框架中，本科生到海外与世界知名的研究小组合作。这个高度协作的综合和计算研究计划之间的教授小组。德克萨斯大学奥斯汀分校的Simon M. Humphrey和Graeme Henkelman专注于合成和研究具有不同寻常成分的新型贵金属纳米颗粒催化剂。这项研究活动的主要目标是在新型金属纳米颗粒的结构和功能之间建立直接联系，这些纳米颗粒是由稀有金属的不寻常的二元和三元组合组成的。要实现这一目标，存在着重大的智力挑战。首先，确定支撑的多组分金属纳米粒子的原子结构是困难的。结合电子显微镜，总x射线散射生成对分布函数数据，扩展x射线精细结构光谱和温度编程解吸/反应将用于实验量化结构参数。这些数据将用于在原子尺度上建立现实的理论模型。其次，具有原子细节的结构信息对于建立活性位点、反应性描述符和选择性预测的理论模型也至关重要。同样重要的是，从理论预测方面得到反馈，可以通过实验进行测试，这样模型就可以得到验证和校准。这项工作的最终目标是能够合理地预测新催化剂的最佳结构和组成，这些催化剂应该具有特定应用所需的反应性。同时，预测和实验观察到的反应性之间的差异对于改进本工作中开发的计算方法同样有价值。该项目还通过与创新的本科教育项目（称为奥斯汀国际框架（AIF））的整合而得到显著增强。AIF是一个创新和现代思维的项目，为德州大学奥斯汀分校的本科生提供完全身临其境的奖学金支持的国际交流体验。它为学生提供了一个独特的机会，通过亲眼目睹科学的全球性，拓宽他们的视野。参与该计划的学生可以获得研究经验的课程学分，并提供奖学金以支付他们在海外进行研究期间的基本生活费用。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。

This a collaborative synthetic and computational research program between the groups of Profs. Simon M. Humphrey and Graeme Henkelman at the University of Texas at Austin, which focuses on the preparation and studies of new nano-catalyst materials. Catalysts reduce the total energy used in large-scale chemical processes, including the synthesis of fuels, polymers and textiles, drugs, and the remediation of environmental pollutants. Catalysts also reduce the amount of waste by-products that are generated. The majority of catalysts currently in use are based on precious metals, which are unfortunately also both scarce and expensive. Therefore, it is critically important to find ways to prepare modern catalysts that can operate using less total metal, whilst maintaining their catalytic performance. With support from the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, this project directly addresses these issues by studying the synthesis and properties of metallic nanoparticle catalysts that comprise only a few thousand atoms per entity; nanoparticles are attractive compared with bulk metals because they exhibit superior reactivity, as well as having very large surface areas compared to their volumes. The project also studies the use of scalable and environmentally-sustainable synthesis methods, such as microwave heating, to prepare new nanoparticle catalysts comprised of previously unstudied mixtures of precious metals. The fundamental properties of these new catalysts are assessed using experimental and theoretical (computational) methods, in order to understand how composition relates to performance improvements in real chemical reactions. The ultimate aim is to apply experimental and computational expertise to predict new catalyst compositions that should have optimal properties for given industrial processes. The project is also significantly enhanced through integration with an innovative new undergraduate educational program, called the Austin-International Framework in which undergraduates travel overseas to collaborate with world-renown research group. This highly collaborative synthetic and computational research program between the groups of Profs. Simon M. Humphrey and Graeme Henkelman at the University of Texas at Austin focuses on the synthesis and studies of new noble metal nanoparticle catalysts with unusual compositions. The major objectives of this research activity are to make direct connections between the structure and function of novel metallic nanoparticles that are comprised of unusual binary and ternary combinations of precious metals. There are significant intellectual challenges to achieve this goal. First, determining the atomic structure of supported multicomponent metal nanoparticles is difficult. A combination of electron microscopy, total X-ray scattering to generate pair distribution function data, extended X-ray fine structure spectroscopy, and temperature programmed desorption/reaction will be used to experimentally quantify structural parameters. This data will be used to inform realistic theoretical models at the atomic scale. Second, structural information with atomic detail is also critical to building theoretical models of active site, reactivity descriptors, and predictions of selectivity. It is also important to have feedback in terms of predictions from theory that can be tested experimentally, so that the models can be validated and calibrated. The ultimate goal of this work is to be able to rationally predict optimal structures and compositions of new catalysts that should have desired reactivity for specific applications. Meanwhile, differences between predictions and experimentally observed reactivity are equally valuable for improving the computational methods developed in this work. The project is also significantly enhanced through integration with an innovative new undergraduate educational program, called the Austin-International Framework (AIF). The AIF is an innovative and modern-thinking program that provides a fully immersive, scholarship-supported international exchange experience to UT Austin undergraduates. It provides students the unique opportunity to broaden their horizons by witnessing first-hand the global nature of science. The students involved in this program receive course credit for their research experiences and scholarships are provided to cover their basic cost-of-living expenses while doing research overseas.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.