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Structural and Reactivity Effects of Secondary Metal Doping into Iron-Nitrogen-Carbon Catalysts for Oxygen Electroreduction

Structural and Reactivity Effects of Secondary Metal Doping into Iron-Nitrogen-Carbon Catalysts for Oxygen Electroreduction

Authors :
Luo, Fang
Roy, Aaron
Sougrati, Moulay Tahar
Khan, Anastassiya
Cullen, David A.
Wang, Xingli
Primbs, Mathias
Zitolo, Andrea
Jaouen, Frédéric
Strasser, Peter
Source :
Journal of the American Chemical Society; 20230101, Issue: Preprints
Publication Year :
2023

Abstract

While improved activity was recently reported for bimetallic iron-metal-nitrogen-carbon (FeMNC) catalysts for the oxygen reduction reaction (ORR) in acid medium, the nature of active sites and interactions between the two metals are poorly understood. Here, FeSnNC and FeCoNC catalysts were structurally and catalytically compared to their parent FeNC and SnNC catalysts. While CO cryo-chemisorption revealed a twice lower site density of M-Nxsites for FeSnNC and FeCoNC relative to FeNC and SnNC, the mass activity of both bimetallic catalysts is 50–100% higher than that of FeNC due to a larger turnover frequency in the bimetallic catalysts. Electron microscopy and X-ray absorption spectroscopy identified the coexistence of Fe-Nxand Sn-Nxor Co-Nxsites, while no evidence was found for binuclear Fe-M-Nxsites. 57Fe Mössbauer spectroscopy revealed that the bimetallic catalysts feature a higher D1/D2 ratio of the spectral signatures assigned to two distinct Fe-Nxsites, relative to the FeNC parent catalyst. Thus, the addition of the secondary metal favored the formation of D1 sites, associated with the higher turnover frequency.

Details

Language :
English
ISSN :
00027863 and 15205126
Issue :
Preprints
Database :
Supplemental Index
Journal :
Journal of the American Chemical Society
Publication Type :
Periodical
Accession number :
ejs63397376
Full Text :
https://doi.org/10.1021/jacs.3c03033