Reaction kinetics of protons and oxide ions in LSM/lanthanum tungstate cathodes with Pt nanoparticle activation

Strandbakke, R., Dyrlie, O., Hage, F. S. and Norby, T. (2016) Reaction kinetics of protons and oxide ions in LSM/lanthanum tungstate cathodes with Pt nanoparticle activation. Journal of the Electrochemical Society, 163(6), F507-F515. (doi: 10.1149/2.0881606jes)

Abstract

Composite electrodes of La0.8Sr0.2MnO3 (LSM)/La28–xW4+xO54+3x/2 (x = 0.85, “LWO56”) on LWO56 electrolytes have been characterized by use of electrochemical impedance spectroscopy vs. pO2 and temperature from 900°C, where LWO56 is mainly oxide ion conducting, to 450°C, where it is proton conducting in wet atmospheres. The impedance data are analyzed in a model which takes into account the simultaneous flow of oxide ions and protons across electrolyte and electrodes, allowing extraction of activation energies and pre-exponential factors for the partial electrode reactions of protons and oxide ions. One composite electrode was infiltrated with Pt nanoparticles with average diameter of 5 nm, lowering the overall electrode polarization resistance (Rp) at 650°C from 260 to 40 Ω cm2. The Pt-infiltrated electrode appears to be rate limited by surface reactions with activation energy of ∼90 kJ mol−1 in the low temperature proton transport regime and ∼150 kJ mol−1 in the high temperature oxide ion transport regime. The charge transfer reaction, which makes a minor contribution to Rp, exhibits activation energies of ∼85 kJ mol−1 for both oxide ion and proton charge transfer.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Hage, Dr Fredrik Sydow
• Authors: Strandbakke, R., Dyrlie, O., Hage, F. S., and Norby, T.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Journal of the Electrochemical Society
• Publisher: The Electrochemical Society
• ISSN: 0013-4651
• ISSN (Online): 1945-7111
• Published Online: 17 March 2016
• Copyright Holders: Copyright © 2016 The Electrochemical Society
• First Published: First published in Journal of the Electrochemical Society 163(6): F507-F515
• Publisher Policy: Reproduced in accordance with the publisher copyright policy