Probing the Influence of the Carbon Support on the Activity of Fe-N 3 /C Model Active Sites for the Oxygen Reduction Reaction

Abstract

We report here an investigation of the role that various carbon supports have on a model non-precious metal catalyst for the oxygen reduction reaction (ORR) prepared through a molecularly defined terpyridine moiety covalently embedded onto various high surface area carbons (Black Pearls 2000, Ketjen Black 600, Multi-Walled Carbon Nanotubes). A terpyridine modified catalyst has been previously prepared and allowed for the controlled deposition of one specific and unique N 3 /C active site on the surface of the support. The effect of changing the porosity and surface area of the carbon was analyzed for its oxygen reduction reaction activity and characterized using thermogravimetric analysis, pore size determination, and rotating disk measurements. This system showed that when a more microporous support was used the activity for the oxygen reduction reaction was significantly decreased in acidic media, this could be explained by the differences in the formation and overall accessibility of the active sites on the high surface area supports.