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

Georgia Tech Research Corporation, Atlanta GA

Investigators

Abstract

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.