Continuous and Scalable Manufacturing of Platinum-Nickel Nanocatalysts for Polymer Electrolyte Membrane Fuel Cells

具有可控形状的金属纳米晶在能源转换、环境保护和化学/医药制造等方面的应用是必不可少的。尽管它们的合成最近取得了进展，但在将纳米晶体从学术研究过渡到工业应用方面仍然存在重大差距，这主要是因为缺乏在不影响质量的情况下在工业规模上制造它们的能力。最近的演示表明，连续流动液滴反应器为可扩展和低成本地生产尺寸均匀、形状可控的金属纳米晶体提供了一个实用的平台。基于液滴的平台提供了一种可线性扩展的技术，该技术可以在基本上相同的条件下分别在小批量和大批量下运行，以实现协议优化和制造的目的。除了科技进步，该奖项还将有助于在非制造业、材料科学、催化、胶体科学和能源技术等不同学科之间建立联系。它还在以下两个方面对社会产生了直接影响：制造燃料电池的纳米催化剂，这是一种真正的零排放技术，对环境保护至关重要；通过让女性、少数族裔和其他代表性不足的群体参与这个项目，促进高等教育的多样性。通过与日产的合作者合作，该团队旨在开发一种可扩展制造八面体铂镍纳米晶体的新技术。这种双金属纳米晶已经在间歇反应器中生产出来，并显示出对氧还原的最高活性，氧还原是发生在聚合物电解质膜燃料电池(PEMFC)阴极上的关键反应。然而，由于批次之间的重复性差以及合成之间不可避免的差异，获得足够数量的均匀纳米晶用于器件测试已被证明是具有挑战性的。通过这一奖项，将根据动力学测量确定金属前体和还原剂的最佳组合，以确保还原不会过早发生，而只在液滴反应器通过高温下保持的反应区时才会发生。还将开发一种类似的协议，在铂-镍八面体表面共形覆盖1-2个原子层厚的铂壳，以极大地增强其催化活性。这些催化剂将由日产的工程师进行测试，并在以质子交换膜燃料电池为动力的车辆上进行商业使用评估。这项研究将为未来基于形状可控的纳米晶的工业催化剂的应用铺平道路。

Metal nanocrystals with controlled shapes are essential to a variety of applications, including energy conversion, environmental protection, and chemical/pharmaceutical manufacturing. Despite recent progress in their synthesis, there still exists a major gap in transitioning the nanocrystals from academic studies to industrial applications, primarily due to the lack of ability to manufacture them at an industrially relevant scale without compromising quality. Recent demonstrations indicate that continuous-flow droplet reactors offer a practical platform for the scalable and cost-effective production of metal nanocrystals with uniform sizes and controlled shapes. The droplet-based platform offers a linearly scalable technology that can be operated at both small and large quantities under essentially identical conditions for the purposes of protocol optimization and manufacturing, respectively. In addition to the scientific and technological advances, this award will help forge links between different disciplines that include nonmanufacturing, materials science, catalysis, colloidal science, and energy technology. It also has immediate impacts on the society in the following two aspects: manufacturing of nanocatalysts for fuel cells, a truly zero-emission technology critical to environmental protection; and promotion of diversity in higher education by engaging women, minorities, and other underrepresented groups into this project.In working with its collaborators at Nissan, the team aims to develop a new technology for the scalable manufacturing of octahedral platinum-nickel nanocrystals. Such bimetallic nanocrystals have been produced in batch reactors and demonstrated with the highest activity toward oxygen reduction, a key reaction occurring on the cathodes of polymer electrolyte membrane fuel cells (PEMFCs). However, due to the poor batch-to-batch reproducibility and inevitable variations between syntheses, it has proven challenging to obtain an adequate amount of uniform nanocrystals for device testing. Through this award, an optimal combination of metal precursors and reductant will be identified based on kinetic measurements to ensure that the reduction will not occur prematurely, and instead only when the droplet reactors pass through a reaction zone held at an elevated temperature. A similar protocol will also be developed to conformally coat the surfaces of platinum-nickel octahedra with platinum shells of 1-2 atomic layers thick to greatly enhance their catalytic activity. The catalysts will be tested by engineers at Nissan and evaluated for commercial use in vehicles powered by PEMFCs. This research will pave the way for future deployment of industrial catalysts based on nanocrystals with controlled shapes.