PhD Thesis Defence Presentations - Fotios Zaravelis

Τίτλος Παρουσίασης (Presentation Title): Development, characterization, and performance assessment of modified Ni/GDC electrocatalysts for the reversible operation of solid oxide cells (rSOCs)
Presentation Type (Τύπος Παρουσίασης): Υποστήριξη Διδακτορικής Διατριβής
Ονοματεπώνυμο Ομιλητή (Speakers Full Name): Φώτης Ζαραβέλης
Προέλευση Ομιλητή (Speakers Affiliation): University of Patras, Department of Chemical Engineering
Seminar Room (Αίθουσα): Βιβλιοθήκη "Αλκιβιάδης Χ. Παγιατάκης"
Ημερομηνία: Δευ, 18 Σεπ 2023, Ώρα: 13:00 - 16:00
Διεύθυνση Διαδικτυακής Μετάδοσης: PhD Defense - F. Zaravelis
Περίληψη (Abstract)

The operation of solid oxide cells (SOC) at high temperatures offers several advantages, which are reflected in better performance and reduced losses due to favorable thermodynamics and kinetics of the reactions. These cells provide flexibility to switch between electrolysis and fuel oxidation processes, making them ideal for both energy production (X-to-Power) and chemical production and storage (Power-to-X).

In this dissertation, cermet electrocatalysts were developed based on commercially available NiO/GDC powder (65 wt.% NiO - 35 wt.% Ce0.9Gd0.1O2-x) modified through chemical methods with transition metals such as Au, Fe, and Mo, aiming for their operation under reverse solid oxide fuel cell (rSOC) conditions. The initial efforts focused on optimizing the already studied electrode 0.4 wt.% Mo - 3 wt.% Au - Ni/GDC, with the primary goal of reducing the Au content and then finding the optimal ratio of Au to Mo. Subsequently, compositions of new electrocatalysts were created by depositing Au and Fe metals with different weight percentages (0.5 wt.% and 3 wt.% Au) to investigate the effect of metal concentration on the electrocatalyst's performance. Suitable pastes were prepared from the modified NiO/GDC powders and deposited as fuel electrodes on ceramic electrolyte 8YSZ (ZrO2 stabilized with 8 mol.% Y2O3) using screen printing. An LSCoF (La0.6Sr0.4Co0.8Fe0.2O3-δ) commercial perovskite was used as an oxygen electrode.

To determine the impact of each modification on the physical-chemical and electrochemical characteristics of Ni/GDC, a series of methods were applied under different experimental conditions. Extensive physicochemical analysis of the electrodes, both in powder and half-cell forms, was conducted using techniques such as BET, SEM, XRD, H2-TPR, H2O-TPO, and in-situ H2O XPS. Electrochemical characterization was carried out over a range of temperatures from 900 to 800 °C, with the introduction of different gas mixtures (H2O/H2), switching between solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOE) operation. Data of voltage-current density (V-i) were recorded under these conditions with simultaneous analysis through Electrochemical Impedance Spectroscopy (EIS). The modified Fe-Au-Ni/GDC electrode with the best electrochemical performance was studied in a comparative stability experiment with Ni/GDC under reverse solid oxide fuel cell (rSOC) conditions. Finally, a detailed electrokinetic study of these two electrodes was performed, both in fuel cell and electrolysis cell operation, using comprehensive EIS spectra under different experimental conditions. The goal of these experiments was to calculate key kinetic parameters, such as the apparent order of the studied reaction, and to determine the effect of modifications with Fe and Au.

Σύντομο Βιογραφικό Ομιλητή (Speakers Short CV)
Education

PhD thesis (2019-2023)

Department of Chemical Engineering, University of Patras

Foundation for Research and Technology – Hellas, Institute of Chemical Engineering Sciences (FORTH/ICEHT)

Title: Development, characterization, and performance assessment of modified Ni/GDC electrocatalysts for the reversible operation of solid oxide cells (rSOCs)

Supervisor: Stylianos Neophytides

Chemical Engineering Diploma (2014-2019)

Department of Chemical Engineering, University of Patras

Grade: 7.68/10.0

Publications
  1. Zaravelis, F., & Niakolas, D. K. (2023). Enhancement of the intrinsic Ni/GDC activity under rSOC operation by means of Fe–Au doping: An electro-kinetic study. International Journal of Hydrogen Energy. doi.org/10.1016/j.ijhydene.2023.06.034 
  2. Zaravelis, F., Sygellou, L., Souvalioti, A., & Niakolas, D. K. (2023). Transition metals in Ni/GDC for the reversible solid oxide cell operation: Optimization of the Mo-Au-Ni synergy and further enhancement via substitution of Mo with Fe. Electrochimica Acta, 453, 142343. doi.org/10.1016/j.electacta.2023.142343
  3. Vibhu, V., Vinke, I. C., Zaravelis, F., Neophytides, S. G., Niakolas, D. K., Eichel, R. A., & de Haart, L. G. J. (2022). Performance and Degradation of Electrolyte-Supported Single Cell Composed of Mo-Au-Ni/GDC Fuel Electrode and LSCF Oxygen Electrode during High Temperature Steam Electrolysis. Energies, 15(8), 2726. doi.org/10.3390/en15082726
  4. Zaravelis, F., Theodorakis, N., Triantafyllou, A., & Stivanakis, V. (2018). Fly ash of Megalopolis and ferroalumina in the production of building materials. Materials Today: Proceedings, 5(4), 27434–27440. doi.org/10.1016/j.matpr.2018.09.061
Conferences
  1. Zaravelis, F., Neophytides, S.G. and Niakolas, D.K. Finding the optimum loading of Au & Mo in NiO/GDC, for the reversible operation of solid oxide cells, 16th Panhellenic Catalysis Symposium (2023) (Poster presentation)
  2. Zaravelis, F., Neophytides, S.G. and Niakolas, D.K. Finding the optimum loading of Au & Mo in NiO/GDC, and replacement of Mo with Fe, for the reversible operation of solid oxide cells, 15th European SOFC & SOE Forum (2022) (Poster presentation)
  3. Zaravelis, F., Neophytides, S.G. and Niakolas, D.K. Finding the optimum loading of Au & Mo in NiO/GDC, and replacement of Mo with Fe, for the reversible operation of solid oxide cells, 13th Panhellenic Scientific Conference on Chemical Engineering (2022) (Oral presentation)
  4. Zaravelis, F., Neophytides, S.G. and Niakolas, D.K. Finding the optimum loading of Au & Mo in NiO/GDC, and replacement of Mo with Fe, for the reversible operation of solid oxide cells, 5th International Workshop on Degradation Issues of Fuel Cells and Electrolysers (2022) (Oral presentation)
  5. Neofytidis, Ch., Ioannidou, E., Zaravelis, F., Neophytides, S.G. and Niakolas, D.K. Transition Metal Elements as Ni/GDC modifiers for the Solid Oxide H2O Electrolysis; the case of Fe. 14th European SOFC & SOE Forum (2020) (Poster presentation)
  6. Zaravelis, F., Niakolas, D.K., Neophytides, S.G, Paloukis, F., Vayenas, C.G., Katsaounis, A. and Buergler, B. High pressure PEM electrolysis stack as part of a Regenerative Fuel Cell System. 5thWorkshop of Graduates & Post-Docs in Chemical Engineering Sciences (2019) (Oral presentation)
  7. Neophytides, S.G., Niakolas, D.K., Paloukis, F., Zaravelis, F.,  Vayenas, C.G., Katsaounis, A., Schautz, M. and Buergler, B. High pressure PEM electrolysis stack as part of a Regenerative Fuel Cell System. 13th Panhellenic Scientific Conference on Chemical Engineering (2019) (Poster presentation)
  8. Niakolas, D.K., Neophytides, S.G., Paloukis, F., Zaravelis, F.,  Vayenas, C.G., Katsaounis, A., Schautz, M. and Buergler, B. High pressure PEM electrolysis stack as part of a Regenerative Fuel Cell System. 4th Workshop of Graduates & Post-Docs in Chemical Engineering Sciences (2018) (Poster presentation)
  9. Neophytides, S.G., Niakolas, D.K., Paloukis, F., Zaravelis, F.,  Vayenas, C.G., Katsaounis, A., Schautz, M. and Buergler, B. High pressure PEM electrolysis stack as part of a Regenerative Fuel Cell System. 15th Panhellenic Catalysis Symposium (2018) (Poster presentation)
  10. Zaravelis, F., Theodorakis, N., Triantafyllou, A. and Stivanakis, V. Fly ash of Megalopolis and ferroalumina in the production of building materials. 12th Panhellenic Scientific Conference on Chemical Engineering (2017) (Oral presentation)
Participation in Scientific Projects
  1. Reversible SOEC/SOFC System for a zero emissions network energy system [24_7 Zen, GA: 101101418, 2023-2027]
  2. Development of electrocatalysts/electrodes for the investigation of the reversible electrolysis/fuel cell process on Solid Oxide high temperature cells (rSOC) [NewSOC, GA: 874577, 2020 – 2023]
  3. Development of new electrode materials and understanding of degradation mechanisms on Solid Oxide High Temperature Electrolysis Cells [SElySOs, GA: 671481, 2016 – 2020]
  4. High pressure PEM electrolysis stack as part of a regenerative fuel cell system [ESA, GA: 4000109578/13/NL/SC, 2014-2021]