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Unraveling the Nature of Sites Active toward Hydrogen Peroxide Reduction in Fe‐N‐C Catalysts
Author(s) -
Choi Chang Hyuck,
Choi Won Seok,
Kasian Olga,
Mechler Anna K.,
Sougrati Moulay Tahar,
Brüller Sebastian,
Strickland Kara,
Jia Qingying,
Mukerjee Sanjeev,
Mayrhofer Karl J. J.,
Jaouen Frédéric
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201704356
Subject(s) - catalysis , chemistry , hydrogen peroxide , carbon fibers , fuel cells , active site , electrolyte , inorganic chemistry , hydrogen , combinatorial chemistry , chemical engineering , organic chemistry , materials science , electrode , composite number , engineering , composite material
Fe‐N‐C catalysts with high O 2 reduction performance are crucial for displacing Pt in low‐temperature fuel cells. However, insufficient understanding of which reaction steps are catalyzed by what sites limits their progress. The nature of sites were investigated that are active toward H 2 O 2 reduction, a key intermediate during indirect O 2 reduction and a source of deactivation in fuel cells. Catalysts comprising different relative contents of FeN x C y moieties and Fe particles encapsulated in N‐doped carbon layers (0–100 %) show that both types of sites are active, although moderately, toward H 2 O 2 reduction. In contrast, N‐doped carbons free of Fe and Fe particles exposed to the electrolyte are inactive. When catalyzing the ORR, FeN x C y moieties are more selective than Fe particles encapsulated in N‐doped carbon. These novel insights offer rational approaches for more selective and therefore more durable Fe‐N‐C catalysts.