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Correlation between hydrogen production rate, current, and electrode overpotential in a solid oxide electrolysis cell with La 0.6 Sr 0.4 FeO 3- δ thin-film cathode.

Correlation between hydrogen production rate, current, and electrode overpotential in a solid oxide electrolysis cell with La 0.6 Sr 0.4 FeO 3- δ thin-film cathode.

Authors :
Walch G
Opitz AK
Kogler S
Fleig J
Source :
Monatshefte fur chemie [Monatsh Chem] 2014; Vol. 145 (7), pp. 1055-1061. Date of Electronic Publication: 2014 May 24.
Publication Year :
2014

Abstract

Abstract: A solid oxide electrolysis cell (SOEC) with a model-type La <subscript>0.6</subscript> Sr <subscript>0.4</subscript> FeO <subscript>3- δ </subscript> thin-film cathode (working electrode) on an yttria-stabilized zirconia electrolyte and a porous La <subscript>0.6</subscript> Sr <subscript>0.4</subscript> Co <subscript>0.2</subscript> Fe <subscript>0.8</subscript> O <subscript>3- δ </subscript> counterelectrode was operated in wet argon gas at the cathode. The hydrogen formation rate in the cathode compartment was quantified by mass spectrometry. Determination of the current as well as outlet gas composition revealed the electrochemical reduction of some residual oxygen in the cathodic compartment. Quantitative correlation between gas composition changes and current flow was possible. At 640 °C a water-to-hydrogen conversion rate of ca. 4 % was found at -1.5 V versus a reversible counterelectrode in 1 % oxygen. Onset of hydrogen formation could already be detected at voltages as low as -0.3 V. This reflects a fundamental difference between steam electrolysis and electrolysis of liquid water: substantial hydrogen production in a SOEC is already possible at pressures much below ambient. This causes difficulties in determining the cathodic overpotential of such a cell.

Details

Language :
English
ISSN :
0026-9247
Volume :
145
Issue :
7
Database :
MEDLINE
Journal :
Monatshefte fur chemie
Publication Type :
Academic Journal
Accession number :
26166894
Full Text :
https://doi.org/10.1007/s00706-014-1220-y