Influence of Precursor Functional Groups on the Formation and Performance of Iron-Coordinating Ordered Mesoporous Carbons as Fuel Cell Catalysts
Journal article, 2017
We examine the influence of precursor functional groups on the formation and electrocatalytic performance of iron ion-chelating ordered mesoporous carbon (Fe-OMC) fuel cell catalysts. First, we study whether the active sites in these catalysts consist of Fe-N-x or Fe-O-x chelates. To verify this, catalysts were prepared from two different molecular precursors (furfurylamine and furfuryl alcohol) and the functional groups' (-NH2 vs -OH) role in the formation of iron ion-chelating active sites in the catalysts was established. From electrochemical tests and EPR spectroscopy, conspicuously different behaviors were obtained for the catalyst prepared from furfurylamine compared to that prepared from furfuryl alcohol. It was unambiguously established that the amine group is central to the formation of electrocatalytically active sites in Fe-OMC catalysts and that these are of the Fe-N-x-OMC type. Additional Fe-OMC catalysts were prepared with the purpose to determine the influence of the two precursors on the formation of the carbon matrix. By complementing the furfurylamine with the more readily polymerizing furfuryl alcohol and using a mixture of the two as precursor solution in the synthesis, an overall improvement over the pure furfurylamine was achieved. The mixture gave a catalyst with, a larger pore volume and surface area, a higher conductivity, and a higher oxygen conversion rate.