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

这是一个合作的合成和计算研究计划之间的教授组。西蒙·M德克萨斯大学奥斯汀分校的Humphrey和GraemeHenkelman博士说，该研究所专注于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、药物的合成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，贵金属也是稀缺和昂贵的。因此，至关重要的是找到制备现代催化剂的方法，这些催化剂可以使用更少的总金属，同时保持其催化性能。在化学部大分子，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几千个原子的金属纳米颗粒催化剂的合成和性质直接解决了这些问题;与块状金属相比，纳米颗粒具有吸引力，因为它们表现出上级反应性，以及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）方法评估这些新催化剂的基本性质，以了解组成如何与真实的化学反应中的性能改进相关。最终目的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。该项目还通过与创新的新本科教育计划相结合而得到显着增强，该计划被称为奥斯汀国际框架，本科生前往海外与世界知名的研究小组合作。这个高度合作的合成和计算研究计划之间的教授组。西蒙·M德克萨斯大学奥斯汀分校的Humphrey和Graeme Henkelman专注于合成和研究具有不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建立新型金属纳米颗粒的结构和功能之间的直接联系，这些纳米颗粒由贵金属的不寻常的二元和三元组合组成。实现这一目标面临着重大的智力挑战。首先，确定负载的多组分金属纳米颗粒的原子结构是困难的。电子显微镜，总X射线散射生成对分布函数数据，扩展的X射线精细结构光谱，和程序升温解吸/反应的组合将用于实验量化结构参数。这些数据将用于在原子尺度上为现实的理论模型提供信息。第二，原子细节的结构信息也是至关重要的活性位点，反应性描述符，并预测选择性的理论模型的建立。同样重要的是，在理论预测方面要有反馈，这些预测可以通过实验进行检验，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是同样有价值的，以改善在这项工作中开发的计算方法。该项目还通过与创新的新本科教育计划（称为奥斯汀国际框架（AIF））的整合得到了显着增强。AIF是一个创新和现代思维的计划，为UT奥斯汀的本科生提供完全沉浸式的，奖学金支持的国际交流体验。它为学生提供了独特的机会，通过亲眼目睹科学的全球性来拓宽视野。参与该项目的学生将获得课程学分，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NSF的法定使命，并通过使用基金会的智力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.