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On the effect of sulfite ions on the structural composition and ORR activity of Fe-N-C catalysts

Wagner, S. and Martinaiou, I. and Shahraei, A. and Weidler, N. and Kramm, U. I. (2018):
On the effect of sulfite ions on the structural composition and ORR activity of Fe-N-C catalysts.
In: Hyperfine Interactions, Springer, Netherlands, p. 10, 239, (1), ISSN 0304-3843,
DOI: 10.1007/s10751-017-1485-8,
[Online-Edition: https://doi.org/10.1007/s10751-017-1485-8],
[Article]

Abstract

Fe-N-C catalysts are the most promising group of non-precious metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). This study focusses on two different porphyrin-based Fe-N-C catalysts and a Fe-N-C catalyst prepared from alternative precursors under S-addition. Catalysts are subjected to a wet-chemical poisoning treatment by sulfite ions . A mechanism for the deactivation process of the active sites is proposed. ORR activity is evaluated for the original catalysts (OC) and for the poisoned catalysts in 0.1 M H2SO4. In addition, the structural composition of the catalysts is identified by Mobauer spectroscopy. Our results show that the sulfite ions bound irreversible to the catalysts and the catalysts lose significant fractions of their ORR activity while in Mobauer spectroscopy a new doublet appears. Based on the results, possible models for the binding of the ambident sulfite ion to the FeN4 centers are discussed.

Item Type: Article
Erschienen: 2018
Creators: Wagner, S. and Martinaiou, I. and Shahraei, A. and Weidler, N. and Kramm, U. I.
Title: On the effect of sulfite ions on the structural composition and ORR activity of Fe-N-C catalysts
Language: English
Abstract:

Fe-N-C catalysts are the most promising group of non-precious metal catalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). This study focusses on two different porphyrin-based Fe-N-C catalysts and a Fe-N-C catalyst prepared from alternative precursors under S-addition. Catalysts are subjected to a wet-chemical poisoning treatment by sulfite ions . A mechanism for the deactivation process of the active sites is proposed. ORR activity is evaluated for the original catalysts (OC) and for the poisoned catalysts in 0.1 M H2SO4. In addition, the structural composition of the catalysts is identified by Mobauer spectroscopy. Our results show that the sulfite ions bound irreversible to the catalysts and the catalysts lose significant fractions of their ORR activity while in Mobauer spectroscopy a new doublet appears. Based on the results, possible models for the binding of the ambident sulfite ion to the FeN4 centers are discussed.

Journal or Publication Title: Hyperfine Interactions
Volume: 239
Number: 1
Publisher: Springer, Netherlands
Uncontrolled Keywords: Fe-N-C catalyst, Mossbauer spectroscopy, PEMFC, oxygen reduction reaction
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Catalysts and Electrocatalysts
Date Deposited: 11 Dec 2018 11:36
DOI: 10.1007/s10751-017-1485-8
Official URL: https://doi.org/10.1007/s10751-017-1485-8
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