On the oxygen reduction reaction in phosphoric acid electrolyte: Evidence of significantly increased inhibition at steady state conditions

Deng, Y. J.; Wiberg, G. K. H.; Zana, Alessandro; Arenz, Matthias (2016). On the oxygen reduction reaction in phosphoric acid electrolyte: Evidence of significantly increased inhibition at steady state conditions. Electrochimica acta, 204, pp. 78-83. Elsevier Science 10.1016/j.electacta.2016.04.065

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In the presented work, we investigate the oxygen reduction reaction (ORR) in half-cell measurements employing different electrolytes. The aim is to compare the ORR inhibition due to anion adsorption at transient as well as steady state conditions. It is found that the ORR inhibition at the platinum - phosphoric acid electrolyte interface is a relative slow, time dependent process. The major inhibition is not observed in transient polarization curves but only under steady state conditions. This observation is in contrast to the typical ORR inhibition due to anion adsorption as observed for example in sulfuric acid electrolyte. In sulfuric acid the inhibition is fast and then stays more or less constant in time. As a consequence of our findings, common transient measurements of the ORR activity might not be sufficient to investigate suitable mitigation strategies for the ORR inhibition in phosphoric acid electrolyte. Such strategies need to take steady state conditions into account. In order to explain the slow ORR inhibition in phosphoric acid electrolyte, two possible explanations are discussed. Either the adsorption of phosphate is a slow, complex process, where a fast adsorption step is followed by a consecutive filling of the surface, or a mass transfer barrier develops at the polarized phosphoric acid-electrode interface. The latter might be the viscoelectric effect that is known from colloidal science. (C) 2016 Elsevier Ltd. All rights reserved.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Zana, Alessandro and Arenz, Matthias

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

0013-4686

Publisher:

Elsevier Science

Language:

English

Submitter:

Matthias Arenz

Date Deposited:

21 Nov 2016 09:59

Last Modified:

14 Apr 2018 02:30

Publisher DOI:

10.1016/j.electacta.2016.04.065

Web of Science ID:

000376136700008

Uncontrolled Keywords:

anion adsorption phosphoric acid electrolyte ht-pemfc oxygen reduction reaction pt viscoelectric effect hydrogen oxidation reactions single-crystal electrodes membrane fuel-cells absorption spectroscopy polymer electrolyte platinum surfaces alkaline-solution anion adsorption pt(111) electrocatalysis

BORIS DOI:

10.7892/boris.89898

URI:

https://boris.unibe.ch/id/eprint/89898

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