Jump to main content
Jump to site search

Issue 20, 2018
Previous Article Next Article

Infiltrated mesoporous oxygen electrodes for high temperature co-electrolysis of H2O and CO2 in solid oxide electrolysis cells

Author affiliations

Abstract

In the last few years, high temperature solid oxide electrolysis cells (SOECs) have emerged as a promising solution for energy conversion and storage. However, state-of-the-art systems suffer from technological limitations, which prevent their widespread use and market penetration. Particularly, the electrode–electrolyte interface represents a critical element due to the high oxygen potential located in this area, which in turn determines interface delamination. In this context, the use of mesoporous materials, whose architecture is characterized by concatenated nanometric-size pores and high specific surface area, represents a powerful strategy toward the achievement of long-term stability of the electrode. Such structures have been recently proposed as ionically conducting electrode scaffolds for solid oxide fuel cells (SOFCs), exhibiting good performances and low degradation rates. In particular, it has been shown that a highly increased triple phase boundary (TPB)-active points distribution along the electrode may be achieved upon infiltration with a catalytically active material. In this study, infiltrated mesoporous cerium was used as a functional oxygen electrode layer in a fuel electrode supported SOEC system. The results indicate that an enhancement in both long-term stability and electrolysis cell performance are achieved. This is attributed to the decrease in high current density paths and areas of high oxygen potential and to the superior thermal stability of such a nanostructured composite, which allows better current distribution. First, the morphological characterization of the as-synthesized mesoporous Ce0.8Gd0.2O1.9 (CGO), which was carried out by TEM microscopy and low-angle X-ray diffraction (LA-XRD), is presented. A structural and functional investigation of the fuel electrode supported cells, in which the oxygen electrode is composed of catalytically active La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) infiltrating a CGO scaffold, was studied by means of XRD, scanning electron microscopy and spectroscopy, and electrochemical measurements. Characterization under co-electrolysis mode (45% H2O, 45% CO2 and 10% H2) shows an injected current density higher than 1.2 A cm−2 at 1.4 V at 750 °C. Electrochemical impedance spectroscopy was carried out at regular time intervals during galvanostatic (0.5 and 0.75 A cm−2) long-term operation for 1400 h, exhibiting a decrease in polarization resistance and only slight increase in serial resistance during operation. Total degradation rates lower than 2% kh−1 at 0.5 A cm−2 and 1% kh−1 at 0.75 A cm−2 were obtained. Finally, a mechanism for cell degradation based on evolution of the fuel electrode is proposed.

Graphical abstract: Infiltrated mesoporous oxygen electrodes for high temperature co-electrolysis of H2O and CO2 in solid oxide electrolysis cells

Back to tab navigation

Publication details

The article was received on 31 Jan 2018, accepted on 11 Apr 2018 and first published on 14 May 2018


Article type: Paper
DOI: 10.1039/C8TA01045E
J. Mater. Chem. A, 2018,6, 9699-9707
  • Open access: Creative Commons BY-NC license
  •   Request permissions

    Infiltrated mesoporous oxygen electrodes for high temperature co-electrolysis of H2O and CO2 in solid oxide electrolysis cells

    E. Hernández, F. Baiutti, A. Morata, M. Torrell and A. Tarancón, J. Mater. Chem. A, 2018, 6, 9699
    DOI: 10.1039/C8TA01045E

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements