Katherine Ayers1 Chris Capuano1 Luke Dalton1 Prasanna Mani1

1, Proton OnSite, Wallingford, Connecticut, United States

The need for a sustainable source of hydrogen has been widely recognized, not just as a potential transportation fueling vehicles, but to limit CO2 production and fossil fuel consumption from existing industrial processes such as ammonia generation. Currently over 95% of hydrogen is made from fossil fuels through natural gas reforming or coal gasification. However, significant growth has occurred in recent years in water electrolysis research, especially in catalyst research for the hydrogen (HER) and oxygen (OER) evolution reactions. Proton exchange membrane (PEM)-based systems are relatively mature in that the technology has been commercialized, but further research and development can achieve significant impact; for example, order of magnitude reductions in catalyst loading. Anion exchange membranes based systems are still under development, with membrane and ionomer stability in the operating environment being a critical issue. In both the AEM and PEM case, there are complex interactions at the electrode level which need to be considered in catalyst and membrane development. First, the liquid electrolyte environment used for catalyst activity screening, where all of the catalyst surface is accessible to the reactant is often not comparable to a complex, 3-dimensional, ionomer-based electrode. Also, similar to automotive fuel cells, the operating environment is highly important and should be considered when claiming improvements over state of the art. For example, catalyst performance at very low current densities may indicate inherent activity but may not represent capability at typical device operating currents. Similarly, a membrane which cannot operate at differential pressure may be highly limited in utility even if more efficient than current commercial solutions. This talk will describe some of the complex interactions that need to be considered, typical operating requirements, and stages of development where relevant conditions should be introduced.