High temperature Solid Oxide Electrolysis Cells (SOEC) have recently attracted global research interest towards syngas (CO and H₂) production ^[1-3]. Co-electrolysis of CO₂ and water is a key element of power-to-chemicals and power-to-fuel strategies for green chemicals, CO₂ recovery and electricity storage at large scale. High temperature solid oxide co-electrolysis of CO₂ and H₂O is highly efficient to CO and hydrogen production with high reaction rates. Additionally, this technology has the advantage of controlling syngas composition at the outlet by applying the proper potential. This is extremely important when the produced syngas will be fed in conventional Fischer-Tropsch catalytic fuel synthesis reactors ^[4].

The commercialization of co-electrolysis could provide a simpler and cost efficient way for the production of light-fuels compared to other conventional technologies, whereas it is advantageous in that the expected technology development can be based and use the progress of the existing more mature Solid Oxide Fuel Cells technology. At the same time, strategies to achieve technical targets and technology development are expected to lead to significant improvement of the system performance, e.g. thermal and mass integration with other units and components of a complete system (e.g. H₂O vaporizer, CO₂recovery and compressor, methanation reactor etc.).

Several recent studies focus on technical development and operation of Solid Oxide Electrolysers, primarily for water electrolysis but also for the co-electrolysis and fuel conversion process. On the other hand, conventional materials used to construct SOFC cells are not offering the required performance to achieve high efficiency in SOEC devices. Therefore, studies concerning electrode materials and materials of cell structure or electrolytes, as well as cell design are on the top of the research agenda.

This paper summarizes progress in materials aspects for the development and optimization of a solid oxide electrolyser based on perovskitic cathode electrodes able to efficiently perform co-electrolysis of CO₂ and H₂O for syngas production. Laboratory synthesized lanthanum strontium chromites doped with Fe ^[5] have shown adequate efficiency and remarkable stability during co-electrolysis compared to the commercial and state-of-the-art Ni-YSZ material. The study is conducted in the framework of the four-years EU Research project funded by the Fuel Cells and Hydrogen 2 Joint Undertaking, entitled SElySOs: “Development of new electrode materials & understanding of degradation mechanisms on Solid Oxide Electrolysis Cells”.

Acknowledgements

The authors would like to acknowledge financial support from the European Union’s Fuel Cells and Hydrogen 2 Joint Undertaking (SElySOs project, Grant Agreement No. 671481).

References

1. M. Carmo, D.L. Fritz, J. Mergel, D. Stolten, International Journal of Hydrogen Energy 38(2013) 4901-4934.

2. V.N. Nguyen, Q. Fang, U. Packbier, L. Blum, International Journal of Hydrogen Energy 38(2013) 4281-4290.

3. P. Kim-Lohsoontorn, J. Bae, Journal of Power Sources 196(2011) 7161-7168.

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5. K.M. Papazisi, S. Balomenou, D. Tsiplakides, Journal of Applied Electrochemistry 40 (2010) 1875–1881.