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Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts

Sahraie, Nastaran Ranjbar and Kramm, Ulrike I. and Steinberg, Julian and Zhang, Yuanjian and Thomas, Arne and Reier, Tobias and Paraknowitsch, Jens-Peter and Strasser, Peter (2015):
Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts.
In: Nature Communications, Nature Publishing Group, p. 8618, 6, ISSN 2041-1723, [Online-Edition: http://dx.doi.org/10.1038/ncomms9618],
[Article]

Abstract

Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono-and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and Fe-57 Mossbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity.

Item Type: Article
Erschienen: 2015
Creators: Sahraie, Nastaran Ranjbar and Kramm, Ulrike I. and Steinberg, Julian and Zhang, Yuanjian and Thomas, Arne and Reier, Tobias and Paraknowitsch, Jens-Peter and Strasser, Peter
Title: Quantifying the density and utilization of active sites in non-precious metal oxygen electroreduction catalysts
Language: English
Abstract:

Carbon materials doped with transition metal and nitrogen are highly active, non-precious metal catalysts for the electrochemical conversion of molecular oxygen in fuel cells, metal air batteries, and electrolytic processes. However, accurate measurement of their intrinsic turn-over frequency and active-site density based on metal centres in bulk and surface has remained difficult to date, which has hampered a more rational catalyst design. Here we report a successful quantification of bulk and surface-based active-site density and associated turn-over frequency values of mono-and bimetallic Fe/N-doped carbons using a combination of chemisorption, desorption and Fe-57 Mossbauer spectroscopy techniques. Our general approach yields an experimental descriptor for the intrinsic activity and the active-site utilization, aiding in the catalyst development process and enabling a previously unachieved level of understanding of reactivity trends owing to a deconvolution of site density and intrinsic activity.

Journal or Publication Title: Nature Communications
Volume: 6
Publisher: Nature Publishing Group
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Catalysts and Electrocatalysts
07 Department of Chemistry
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 01 Mar 2016 09:06
Official URL: http://dx.doi.org/10.1038/ncomms9618
Identification Number: doi:10.1038/ncomms9618
Funders: Part of this work was financially supported by the German Federal Ministry of Education and Research (Bundesministerium fur Bildung und Forschung, BMBF) under grant 03SF0531B,, Part of this work was financially supported by the Darmstadt Graduate School of Excellence Energy Science and Engineering (GSC 1070).
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