Résumé
Remarkable advancement of platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) makes them a promising alternative to Pt-based catalysts in polymer electrolyte membrane fuel cells (PEMFCs). Commercialization of the Fe-N-C catalysts as the current leading PGM-free ORR catalysts has been hindered by its insufficient activity and durability. Herein, a Fe-N-C catalyst was synthesized
via
chemical vapor deposition of the gas phase anhydrous FeCl
3
onto a metal organic framework (MOF)-derived N-doped carbon (N-C) substrate at 750 ℃. It exhibits excellent ORR activity, with a current density of 33 mA·cm
-2
at 0.90 V
iR-free
(IR-corrected) and 44 mA·cm
-2
at 0.89 V
iR-free
in a H
2
-O
2
PEMFC at 1.0 bar oxygen partial pressure and at a cell temperature of 80°C. The exceptional activity is attributed to the high density of Fe-N
4
sites. Combined characterizations show that the Fe-N
4
sites are exclusively located on the surface of the catalyst and accessible by gas phase oxygen and that the Fe content is 1.8 wt%.
Acknowledgements
This work was supported by the US Department of Energy under award number DE-EE0008416 and DE-EE0008075. The authors acknowledge the support from the DOE Energy Efficiency and Renewable Energy Fuel Cell Technologies Office (DOE-EERE-FCTO) ElectroCat consortium. This research used beamline 6-BM, 7-BM and 8-ID (ISS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Argonne is a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357 by UChicago Argonne, LLC.