A pyridinic Fe-N4 macrocycle models the active sites in Fe/N-doped carbon electrocatalysts
| Autor: | Nathan D. Ricke, Michael L. Pegis, Troy Van Voorhis, Jeffrey T. Miller, Yogesh Surendranath, Alexandra T. Wrobel, Travis Marshall-Roth, Nicole J. Libretto, Kevin J. Anderton |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Molecular model
Science General Physics and Astronomy chemistry.chemical_element 02 engineering and technology 010402 general chemistry Electrochemistry 01 natural sciences General Biochemistry Genetics and Molecular Biology Article Catalysis lcsh:Science X-ray absorption spectroscopy Multidisciplinary biology Active site General Chemistry 021001 nanoscience & nanotechnology 0104 chemical sciences Crystallography chemistry biology.protein lcsh:Q 0210 nano-technology Platinum Selectivity Electrocatalysis Carbon |
| Zdroj: | Nature Communications, Vol 11, Iss 1, Pp 1-14 (2020) Nature Communications |
| ISSN: | 2041-1723 |
| Popis: | 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. Iron- and nitrogen-doped carbon materials are effective catalysts for the oxygen reduction reaction whose active sites are poorly understood. Here, the authors establish a new pyridinic iron macrocycle complex as a more effective active site model relative to legacy pyrrolic model complexes. |
| Databáze: | OpenAIRE |
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