Uric acid-derived Fe_3C-containing mesoporous Fe/N/C composite with high activity for oxygen reduction reaction in alkaline medium

摘要

In this work, a category of Fe3C-containing Fe/N/C mesoporous material has been fabricated by carbonizing the mixture of uric acid, Iron (III) chloride anhydrous and carbon support (XC-72) under different pyrolysis temperature. Of all these samples, pyrolysis temperature (800 degrees C) becomes the most crucial factor in forming Fe3C active sites which synergizes with high content of graphitic N to catalyze oxygen reduction reaction (ORR). X-ray absorption fine structure spectroscopy (XAFS) is used to exhibit that the space structure around Fe atoms in the catalyst. This kind of catalyst possesses comparable ORR properties with commercial 20% Pt/C (onset potential is 0 V vs. Ag/AgCl in 0.1 M KOH), the average transfer electron number is 3.84 reflecting the 4-electron process. Moreover, superior stability and methanol tolerance deserve to be mentioned.