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Chemical vapor deposition of Fe-N-C oxygen reduction catalysts with full utilization of dense Fe-N4 sites.pdf (2.43 MB)
Chemical Vapor Deposition of Fe-N-C Oxygen Reduction Catalysts with Full Utilization of Dense Fe-N4 Sites
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submitted on 04.09.2020 and posted on 07.09.2020by Li Jiao, Jingkun Li, Lynne Larochelle Richard, Qiang Sun, Thomas Stracensky, Ershuai Liu, Moulay-Tahar Sougrati, Zipeng Zhao, Fan Yang, Sichen Zhong, Hui Xu, Sanjeev Mukerjee, Yu Huang, David A Cullen, Deborah J. Myers, Frederic Jaouen, Qingying Jia
Replacing scarce and expensive platinum (Pt)
with metal-nitrogen-carbon (M-N-C) catalysts for the oxygen reduction reaction
(ORR) in proton
exchange membrane fuel cells (PEMFCs) has largely been
impeded by the low activity of M-N-C, in turn limited by low site density and
low site utilization. Herein, we overcome these limits by implementing chemical
vapor deposition (CVD) to synthesize Fe-N-C, an approach fundamentally different
from previous routes. The Fe-N-C catalyst, prepared by flowing iron chloride
vapor above a N-C substrate at 750 ℃, has a record Fe-N4 site
density of 2×1020 sites·gram-1 with 100% site utilization. A combination of
characterizations shows that the Fe-N4 sites formed via CVD are
located exclusively on the outer-surface, accessible by air, and
electrochemically active. This catalyst delivers an unprecedented current
density of 33
mA·cm-2 at 0.90 ViR-free (iR-corrected)
in an H2-O2 PEMFC at 1.0 bar and 80 ℃.