SGER: Platinum Nanofibers as Fuel Cell Electrodes

University Of Rochester, Rochester NY

Investigators

Abstract

TECHNICAL: Since platinum (Pt) is an effective catalyst but an expensive metal, a structure with a large surface-to-volume ratio is needed to minimize its use. All the available techniques require a support and a good adherence between the support such as carbon and nanoparticles of Pt. The adhesion is generally not good and this is a major source of the durability problem one faces in applications such as fuel cells. A free-standing pure Pt network would also be a welcome ingredient in many other chemical applications and processes, and its development is the focus of this high-risk, high payoff, and transofrmative SGER project. By using a Pt chain compound similar to Magnus green salt, PI can produce a nanowire network of Pt suitable for fuel cell electrodes. However, the size of wire is large. PI would reduce the size to 10 nm. This pure Pt free-standing electrode with or without a support should be more efficient than the ones so far available in which Pt nanoparticles are dispersed in a porous carbon support. In addition, PI can produce nanowires of Pt and Pt/Ni alloys by electro-spinning. The diameter is about 20 nm. PI would aim to get smaller diameters so as to further reduce the use of Pt. These wires can stand alone or mingle with carbon fibers to make electrodes. The high payoff, transformative characteristics of this work would be that without migrating nanoparticles, the wires would be more stable so the resulting fuel cells would be more durable. This design will also be more stable since there are no nanoparticles which could migrate and agglomerate. While the payoff is huge, there are three areas of risk that must be managed and overcome. One is the 3-phase contact points. PI would have to ensure that there are enough 3-phase (gas, electrolyte and electrode) contact points for efficient cell operation. The second is the mechanism of agglomeration. It must be the migration and coalescence of small particles in order to have the benefits of nanowires. The third is the resistivity of nanowires. For that PI plans to plate Pt onto the micro-wires of support. NON-TECHNICAL: Metals are usually in a bulk solid form including fine powders, wires and thin films. Hence it is a challenge to make nanowire network of Pt by chemical means. It requires both the knowledge in chemistry and in materials science. Chemistry is needed to understand the reactions involved and materials science to see how the microstructure was evolved. PI plans to combine these two elements in this SGER research towards the development of robust and efficient electrodes for fuel cells for energy applications. The PI has a doctorate in chemistry but also has many years experience in materials research. He is assisted with a graduate student in Chemical Engineering who has experience in chemical synthesis and another one in materials science who has experience in nanowires. Fuel cell is also an attractive area for graduate, undergraduate, and high school students. PI would involve them and make them aware of the current energy problems.