Influence of iron precursor hydration state on performance of non-precious metal fuel cell catalysts

Abstract

Iron ion-chelating ordered mesoporous carbon (Fe-OMC) catalysts are a class of non-precious metal catalysts for the oxygen reduction reaction in fuel cells. Here, the performance of Fe-OMC catalysts is studied in relation to variations in conditions employed during their synthesis. Specifically, we studied the effects of (i) the hydration state of the iron salt precursor, (ii) the aging time after mixing of the precursor solution and (iii) the relative amount of iron to N/C-precursor used during synthesis. The formation of complexes between the iron ion and the N/C-precursor was investigated by NMR spectroscopy and it was shown that a complex is formed with the amine group of the N/C-precursor being closest to the iron ion. All three parameters studied (i, ii, and iii) were found to have a significant impact on the complex formation between the iron ion and the N/C-precursor as well as on the performance of the resulting catalyst materials.