Nanostructured Catalysts for Alkaline PEM Fuel Cells

A major inhibitor in the adaptation of polymer electrolyte membranes (PEMs) has been the high levels of precious metal catalysts needed for the oxygen reduction reaction (ORR) in state-of-the-art acid-based PEMs. Alkaline PEMs have long held the promise of lowering the need for precious metal catalysts due to acceptable levels of ORR kinetics on non-precious metals. Adaptation of alkaline PEMs has been slow due to low carbon dioxide tolerance, poor membrane chemi- cal stability, poor hydrogen oxidation reaction (HOR) kinetics and poor ionomer electrode interface. A nano-structured novel support for alkaline PEM catalyst layers will be developed. The support will eliminate the difficulties of the catalyst ionomer interface encountered in making alkaline PEM membrane electrode assemblies. This can greatly increase catalyst utilization and improve alkaline PEM ORR and HOR kinetics. Commercial Applications and Other Benefits: PEM fuel cells have long held the promise of efficient energy for back-up power, transportation, and when coupled with an electrolyzer; energy storage for load leveling of renewable energy. In each of these applications fuel cells have the potential to greatly increase efficiency, reducing the amount of energy needed, while greatly lowering CO2 output. To date nearly all of the technology focus has been on acid-based PEMs. As the technology has matured the PGM catalyst costs have become an ever increasing fraction of the total system cost, and continue to be prohibitive. No non-PGM has come close to the performance needed in these applications for the oxygen reduction reaction. One of the only ways known to break through this barrier is to switch from an acidic to an alkaline environment where oxygen reduction kinetics are greatly enhanced. Developing a catalyst layer structure that can take advantage of these kinetics has been challenging. If this technology were to prove successful it would allow the utilization of PEM fuel cells in the aforementioned applications, greatly lowering our nations energy requirement while lowering our carbon emissions.