Open AccessIron and nitrogen-doped double gyroid mesoporous carbons for oxygen reduction in acidic environments
Author(s) -
Fumiaki Matsuoka,
Kevin Fritz,
Peter A. Beaucage,
Fei Yu,
Jin Suntivich,
Ulrich Wiesner
Publication year - 2020
Publication title -
jphys energy
Language(s) - English
Resource type - Journals
ISSN - 2515-7655
DOI - 10.1088/2515-7655/abc31a
Subject(s) - microporous material , mesoporous material , carbon fibers , catalysis , gravimetric analysis , materials science , nitrogen , inorganic chemistry , chemical engineering , chemistry , organic chemistry , composite number , composite material , engineering
Iron- and nitrogen-doped carbon (Fe-N-C) represents a promising class of alternative electrocatalysts to noble metals for the oxygen reduction reaction (ORR) in acidic environments. To make Fe-N-C active, one of the most critical parameters is microporosity, which must be controlled to maximize the active site density. However, the use of microporosity must be optimized for the requirement of high-flux mass transport. Here, we synthesized and demonstrated gyroidal mesoporous Fe-N-C with microporous pore walls as an avenue to combine a high active-site density with favorable mass transport at high flux. The gyroidal mesoporous Fe-N-C catalysts have competitive gravimetric and volumetric ORR activities, comparable to the ORR activity obtained in purely microporous configurations despite having mesoporous features. Our result suggests that the ORR activity of microporous Fe-N-C electrocatalysts can be combined with mesoporosity through the use of mesoporous Fe-N-C with microporous pore walls. We further investigate effects of the nitrogen incorporation method on mesoporous N-doped carbon electrocatalysts. We find that despite having ∼2 × higher N concentration, nitrogen incorporation via NH 3 yields similar ORR activity to incorporation via a chemical additive, a finding we attribute to the role of pyridinic and quaternary N in the ORR.