Boosting the performance in steam electrolysis of solid oxide electrolysis cell by potassium-doping in Sr2Fe1.5Mo0.5O6-δ cathode

• Published in: Journal of cleaner production 2023-10, Vol.424, p.138747, Article 138747
• Main Authors: Li, Hao-Yang, Kamlungsua, Kittiwat, Shin, Jiyoon, Su, Pei-Chen
• Format: Article
• Language: English
• Subjects: adsorption; cathodes; Charge imbalance; dielectric spectroscopy; Double perovskite; electrochemistry; electrolysis; hydrogen; Hydrogen evolution reaction (HER); hydrogen production; oxygen; potassium; Potassium doping; Solid oxide electrolysis cell; Sr2Fe1.5Mo0.5O6-δ; steam; strontium
• ISSN: 0959-6526; 1879-1786
• DOI: 10.1016/j.jclepro.2023.138747

Doping potassium ions (K+) in Sr2Fe1.5Mo0.5O6-δ (SFMO) double perovskite is shown to improve the electrocatalytic activity on hydrogen evolution reaction (HER) in solid oxide electrolysis cells (SOECs). The K+ dopant replaces the A-site strontium ion (Sr2+) in Sr2Fe1.5Mo0.5O6-δ and causes charge imbalance that induced the formation of positively charged defects within Sr2Fe1.5Mo0.5O6-δ and facilitates electrochemical processes in steam electrolysis. The enhanced processes include charge transfer, rate-determining oxide transport and surface hydrogen migration, and steam-dependent water adsorption reactions. Electrochemical impedance spectroscopy results evidently show: (1) Improvement in water adsorption reaction in K0.15Sr1.85Fe1.5Mo0.5O6-δ (K0.15SFMO) due to increase oxygen vacancy concentration for steam electrolysis.(2) The polarization resistance of the cell using K0.15Sr1.85Fe1.5Mo0.5O6-δ decreased by 50% compares to the cell using the Sr2Fe1.5Mo0.5O6-δ electrode. DRT of K0.15SFMO revealed the oxide transport and surface hydrogen migration as the rate-determining step for steam electrolysis. [Display omitted]