Fabrication of Ultra Low Loading Anodes for Proton Exchange Membrane Fuel Cells

Proton Exchange Membrane Fuel Cells (PEMFCs) have proven to be an alternative power source with little to no environmental repercussions. Unfortunately PEMFCs are commercially limited by the high cost of the components needed, such as its precious metal catalyst. After acknowledging the Oxygen Reduction Reaction (ORR) as the limiting reaction within a fuel cell system, it became clear that the amount of catalyst on the anode can be reduced. By using a simple airbrush technique, the amount of catalyst deposited onto an anode can be directly controlled with great accuracy. While this technique is limited by the accuracy of the user, this method continues to show great promise through simple modifications discovered throughout the course of this project. The air brush technique is attractive due to its simplicity and its ability to be industrialized. As an airbrush only requires ink and an air feed, it can easily be used in just about any laboratory setting. Additionally, the properties of the substances that make up the ink solution, allow for simple modifications that greatly improve the accuracy of the catalyst deposition onto a Gas Diffusion Layer (GDL). The ink solution sprayed onto the GDL consist of a catalyst power, water to prevent the catalyst from burning, liquid ionomer, and isopropyl alcohol to aid in the evaporation of water from the solution. Assuming that all of the water and all of the IPA evaporates from the solution upon spraying, a simple dilution results can increase the sensitivity of the technique allowing for a more accurate spray. By spraying a more dilute solution, one can continue to spray the same amount of solution at one time but deposit a smaller amount of catalyst which each passing spray. Initial tests show that these modifications result in anodes with a 75-95% decrease in catalyst. These anodes are then tested under standard procedure and their properties are characterized. Through analysis, the kinetics, peak power densities, mass transport losses and internal resistance losses of the low loading anodes (LLAs) are compared to their standard counterparts. Currently, LLAs perform comparably to standard loading MEAs, and at a 90% decrease in loading have only a 10% decrease in performance. Further optimization and testing may improve these results and continue to cut the cost of PEMFCs, resulting in a viable alternative fuel source.