Proton exchange membrane fuel cells (PEMFCs) are a promising alternative to traditional forms of energy, such as fossil fuels, due to their environmental friendliness. One issue currently plaguing cell efficiency is that hydrogen fuel inevitably contains carbon monoxide (CO) contaminants. Due to the fact that the bonding of CO to Pt is energetically preferable to that of H<sub>2</sub> to Pt, CO adsorbs to active sites on the platinum catalyst, blocking hydrogen fuel conversion and rapidly reducing cell efficiency. Gold (Au) and Ruthenium (Ru) nanoparticles (NPs) have proven to be effective at oxidizing CO and reducing its detrimental effects on PEMFCs; however, their joint effect is largely unstudied. Here, we synthesized gold ruthenium nanoparticles through the two-phase method developed by Brust et al. Monolayers of the AuRu nanoparticles were deposited on Nafion membranes at various surface pressures using the Langmuir-Blodgett (LB) method and tested using a hydrogen fuel cell demonstration kit. By controlling the surface pressure of the LB, we were able to manipulate the compactness of the NP coating. At a surface pressure of 2 mN/m, the AuRu NPs formed a single monolayer of particles that still maintained high density. Because the catalytic effect toward CO oxidation requires direct contact of NPs with the Nafion membrane, overlapping NPs only served to block the active sites. Thus, the surface pressure of 2 mN/m membrane had the ideal monolayer composition. Examining membranes coated at surface pressures of 1 mN/m, 2 mN/m, and 5 mN/m, we find that every membrane coated with AuRu nanoparticles experienced an increased maximum power output. The membrane coated at a surface pressure of 2 mN/m achieved the highest maximum power density in all testing environments. Under atmospheric oxygen conditions, the 2 mN/m membrane achieved a 47.3% increase over the control, with pure oxygen intake it achieved a 21.5% increase over the control, and when exposed to induced 0.1% CO fuel, it achieved a 79.9% increase over the control. The AuRu coated membranes experienced less improvement in pure oxygen conditions as there was no CO<sub>2</sub> present to form CO, diminishing the improvements from CO oxidation. Conversely, a greater improvement was evident in elevated CO conditions because oxidation had a greater effect. The results confirm the viability of gold ruthenium nanoparticles as a method of mitigating CO poisoning in PEMFCs.

Reduction of carbon monoxide poisoning in proton exchange membrane fuel cells via application of gold/ruthenium nanoparticle monolayer

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.