Gaining a better understanding of PGM-free oxygen reduction reaction (ORR) catalyst active site structure and activity relationships is key to developing more active catalysts. In this work, we studied ORR active sites in a variety of Fe-N-C catalysts with a range of activity and durability via in situ catalyst poisoning using thiol-molecular probes. We monitored the selectivity and extent of probe-induced catalyst de-activation by comparing changes in ORR activity of the catalysts and N-containing carbon materials. These experiments were coupled with catalyst degradation and Fe-leaching experiments to better understand the specificity of the molecular probe binding. We plan to use these methods to better understand structural factors of the Fe-N-C active site, as well as the surrounding NC structure that may influence catalyst activity or durability.

Acknowledgement

This work was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) through Electrocatalysis Consortium (ElectroCat).