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

这是一个教授小组之间的合作合成和计算研究计划。Simon M.Humphrey和Graeme Henkelman在德克萨斯大学奥斯汀分校工作，主要从事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，包括燃料合成、聚合物和纺织品、药物以及环境污染物的修复。催化剂还减少了产生的废物副产品的数量。目前使用的大多数催化剂是以贵金属为基础的，不幸的是，贵金属也是稀缺和昂贵的。因此，如何在保持催化性能的同时，用较少的总金属制备现代催化剂就显得尤为重要。在化学系大分子、超分子和纳米化学计划的支持下，该项目通过研究每个实体仅包含数千个原子的金属纳米粒子催化剂的合成和性能来直接解决这些问题；与块状金属相比，纳米粒子具有吸引力，因为它们具有优异的反应活性，以及与其体积相比具有非常大的比表面积。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纳米颗粒催化剂。使用实验和理论(计算)方法对这些新催化剂的基本性质进行了评估，以了解组成与实际化学反应中性能改进的关系。最终目的是应用实验和计算专业知识来预测新的催化剂成分，这些成分对于给定的工业过程应该具有最佳的性能。该项目还通过与一个名为奥斯汀-国际框架的创新本科教育项目的整合而得到显著加强，在该项目中，本科生前往海外与世界知名的研究小组合作。这一高度协作的合成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特殊组成的新型贵金属纳米粒子催化剂。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，这种纳米颗粒由贵金属的不寻常的二元和三元组合组成。要实现这一目标，面临着巨大的智力挑战。首先，确定负载型多组分金属纳米颗粒的原子结构是困难的。电子显微镜、产生对分布函数数据的总X射线散射、扩展X射线精细结构光谱和程序升温脱附/反应将被用于实验量化结构参数。这些数据将被用来提供原子尺度上的现实理论模型。其次，原子细节的结构信息对于建立活性中心、反应性描述符和选择性预测的理论模型也是至关重要的。同样重要的是，从理论上获得预测的反馈也很重要，这些预测可以通过实验进行测试，以便能够验证和校准模型。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，这些结构和组成应该具有特定应用所需的反应活性。同时，预测和实验观察到的反应性之间的差异对于改进这项工作中开发的计算方法同样有价值。该项目还通过与名为奥斯汀-国际框架(AIF)的创新本科教育计划的整合而得到显著增强。AIF是一个创新和现代思维的项目，为德克萨斯大学奥斯汀分校的本科生提供完全身临其境的、由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来开阔他们的视野。参与该项目的学生因其研究经验而获得课程学分，并提供奖学金以支付他们在海外进行研究时的基本生活费。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。

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.