DMREF/Collaborative Research: Design and Testing of Nanoalloy Catalysts in 3D Atomic Resolution

DMREF：合作研究：纳米合金催化剂在三维原子分辨率中的设计和测试非技术描述：该项目旨在发现超小型纳米尺寸的合金催化剂，以提高燃料电池，移动的发电和汽车催化转化器的效率。国家的最先进的实验室和计算机模拟技术将从事探索未知的设计空间的纳米结构的这种应用，并实施降低成本，通过部分替代贵金属，如铂更便宜的替代品。由三名PI组成的团队将使用仿生方法合成新的纳米催化剂，使用世界上最强大的电子显微镜以3D分辨率对所有原子的位置进行成像，并通过多尺度建模和模拟进行预测，在闭环反馈回路中进行燃料电池性能测试。对纳米合金的合成控制、原子级顺序和相关反应性的基本理解将导致合理的设计规则，以优化催化剂性能，并实现有前途的材料的有针对性的改进。预测性多尺度模拟工具的开发和验证也将使更广泛的计算用户群体受益。对合金合成和反应性控制的新的基本见解具有进一步的潜在好处，可以改善商品化学品，磁信息存储，电池，传感器和纳米电子器件的催化剂。本科生、高中生和教师将参加加州大学洛杉矶分校的夏季研究活动，并在阿克伦大学参加一年一度的工程职业日，以鼓励科学和工程领域的职业发展。技术说明：该项目侧重于计算驱动，合理优化纳米合金原子组成和形状，以提高燃料电池中氧还原反应（ORR）的催化性能。具体目标包括Pt-M纳米晶体（M = Fe，Co，Ni，Cu，Cr，Mn）的确定性合成，纳米合金催化剂在原子分辨率和模型改进中的三维表征，以及ORR中反应性的预测，测试和优化。方法包括与分子动力学和动力学蒙特卡罗模拟相结合的仿生合成方案，通过伏安法和密度泛函理论计算进行的ORR性能测试，以及所有反应的原位监测。合成的纳米结构中的原子的坐标将通过电子断层扫描来监测，以识别原子排序，验证和改进原子间势，并预测ORR中的反应速率。合金生长机制，形状控制，和催化性能，通过新的极化和反应力场合金和它们的水界面从第一原理的详细了解将关闭实验能力和缺失的理论理解之间的巨大差距。借助于彻底的实验表征，在1至100 nm的长度尺度上具有前所未有的准确度的预测似乎是可行的，远远超出了量子力学方法的限制，并建立在以前成功的纯金属界面模型（CHARMM-METAL）的基础上。

DMREF: Collaborative Research: Design and Testing of Nanoalloy Catalysts in 3D Atomic ResolutionNon-Technical Description: The project aims at the discovery of ultra-small, nanometer-sized alloy catalysts to improve the efficiency of fuel cells, mobile power generation, and automotive catalytic converters. State-of-the-art laboratory and computer simulation techniques will be engaged to explore the uncharted design space of bimetallic nanostructures for such applications and implement reductions in cost through partial replacement of precious metals such as platinum by cheaper alternatives. The team of three PIs will synthesize new nanocatalysts using biomimetic approaches, image the positions of all atoms in 3D resolution using the world's most powerful electron microscope, and carry out performance tests in fuel cells in a close feedback loop with predictions by multi-scale modeling and simulation. Fundamental understanding of synthesis controls, atomic-scale order, and associated reactivity of the nanoalloys will lead to rational design rules to optimize catalyst performance and enable targeted improvements of promising materials. The development and validation of predictive multi-scale simulation tools will also benefit the broader computational user community. New fundamental insight into alloy synthesis and reactivity controls has further potential benefits to improve catalysts for commodity chemicals, magnetic information storage, batteries, sensors, and nanoelectronic devices. Undergraduate students, high school students, and teachers will be engaged in summer research activities at UCLA and in annual Engineering Career Days at the University of Akron to encourage careers in science and engineering.Technical Description: The project focuses on the computationally driven, rational optimization of nanoalloy atomic composition and shape for catalytic performance in the Oxygen Reduction Reaction (ORR) in fuel cells. Specific aims include the deterministic synthesis of Pt-M Nanocrystals (M = Fe, Co, Ni, Cu, Cr, Mn), the three-dimensional characterization of nanoalloy catalysts in atomic resolution and model refinements, as well as the prediction, tests, and optimization of the reactivity in the ORR. Methods comprise biomimetic synthesis protocols coupled with molecular dynamics and kinetic Monte Carlo simulations, ORR performance testing by voltammetry and density functional theory calculations, and in-situ monitoring of all reactions. The coordinates of the atoms in the synthesized nanostructures will be monitored by electron tomography to identify atomic ordering, to validate and improve interatomic potentials, and to predict reaction rates in ORR. Detailed understanding of alloy growth mechanism, shape control, and catalytic performance through new polarizable and reactive force fields for alloys and their aqueous interfaces from first principles will close a wide gap between experimental capabilities and missing theoretical understanding. Aided by thorough experimental characterization, predictions with unprecedented accuracy at length scales of 1 to 100 nm appear feasible, far beyond the limits of quantum-mechanical methods and building on previous successful models for interfaces of pure metals (CHARMM-METAL).