A pyridinic Fe-N4 macrocycle models the active sites in Fe/N-doped carbon electrocatalysts
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s41467-020-18969-6.pdf
Description
Published version
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1.17 MB
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Checksum (MD5)
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Author(s)
Marshall-Roth, Travis
Libretto, Nicole J
Wrobel, Alexandra T
Anderton, Kevin J
Pegis, Michael L
Ricke, Nathan D
Voorhis, Troy Van
Miller, Jeffrey T
Surendranath, Yogesh
Date Issued
2020
Journal
Nature Communications
Publisher
Springer Science and Business Media LLC
Citation
Marshall-Roth, Travis, Libretto, Nicole J, Wrobel, Alexandra T, Anderton, Kevin J, Pegis, Michael L et al. 2020. "A pyridinic Fe-N4 macrocycle models the active sites in Fe/N-doped carbon electrocatalysts." Nature Communications, 11 (1).
Version
Final published version
Abstract
© 2020, The Author(s). Iron- and nitrogen-doped carbon (Fe-N-C) materials are leading candidates to replace platinum catalysts for the oxygen reduction reaction (ORR) in fuel cells; however, their active site structures remain poorly understood. A leading postulate is that the iron-containing active sites exist primarily in a pyridinic Fe-N4 ligation environment, yet, molecular model catalysts generally feature pyrrolic coordination. Herein, we report a molecular pyridinic hexaazacyclophane macrocycle, (phen2N2)Fe, and compare its spectroscopic, electrochemical, and catalytic properties for ORR to a typical Fe-N-C material and prototypical pyrrolic iron macrocycles. N 1s XPS and XAS signatures for (phen2N2)Fe are remarkably similar to those of Fe-N-C. Electrochemical studies reveal that (phen2N2)Fe has a relatively high Fe(III/II) potential with a correlated ORR onset potential within 150 mV of Fe-N-C. Unlike the pyrrolic macrocycles, (phen2N2)Fe displays excellent selectivity for four-electron ORR, comparable to Fe-N-C materials. The aggregate spectroscopic and electrochemical data demonstrate that (phen2N2)Fe is a more effective model of Fe-N-C active sites relative to the pyrrolic iron macrocycles, thereby establishing a new molecular platform that can aid understanding of this important class of catalytic materials.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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Creative Commons Attribution 4.0 International license
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DOI of Published Version
https://doi.org/10.1038/S41467-020-18969-6
