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

Doping potassium ions (K+) in Sr 2 Fe 1.5 Mo 0.5 O 6-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 Sr 2 Fe 1.5 Mo 0.5 O 6-δ and causes charge imbalance that induced the formation of positively charged defects within Sr 2 Fe 1.5 Mo 0.5 O 6-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 K 0.15 Sr 1.85 Fe 1.5 Mo 0.5 O 6-δ (K 0.15 SFMO) due to increase oxygen vacancy concentration for steam electrolysis.(2) The polarization resistance of the cell using K 0.15 Sr 1.85 Fe 1.5 Mo 0.5 O 6-δ decreased by 50% compares to the cell using the Sr 2 Fe 1.5 Mo 0.5 O 6-δ electrode. DRT of K 0.15 SFMO revealed the oxide transport and surface hydrogen migration as the rate-determining step for steam electrolysis. [Display omitted] [ABSTRACT FROM AUTHOR]