Electrochemical characteristics of Sr-deficient SrTi0.3Fe0.7O3−δ oxygen electrodes for solid oxide electrolyzers.

Developing oxygen electrodes with improved polarization is a major concern for improving the commercial viability of solid oxide electrolyzers (SOECs). SrTi 0.3 Fe 0.7 O 3− δ (STF) has recently emerged as a catalytically active and highly stable oxygen electrode, and its performance has been shown to improve when it is deficient in Sr. However, the mechanism by which Sr deficiency alters the STF polarization behavior still remains to be clarified. In this study, we explored the electrochemical characteristics of Sr 1− x Ti 0.3 Fe 0.7 O 3− δ (STF x ; x = 0.03 and 0.06) to elucidate the effect of Sr deficiency on electrode polarization. The results showed that Sr deficiency effectively improves the electrode/electrolyte interfacial resistance and oxygen-transport kinetics. However, the latter effect was observed to be rather diminished by the degraded microstructure, possibly owing to enhanced sinterability of the Sr-deficient compositions. Symmetric cell life tests conducted over ∼1110 h revealed that STF x maintains low polarization to prevent electrode delamination. The Ni–YSZ supported cell with the STF0.06 electrode exhibits improved steam electrolysis performance, yielding a high current density of ∼2.71 A cm–2 at 750 °C and 1.3 V. • Electrochemical evaluation of Sr-deficient SrTi 0.3 Fe 0.7 O 3−δ oxygen electrodes. • Sr deficiency improves electrode/electrolyte interfacial contact and O 2 transport. • Reduced porosity and surface area are observed for Sr-deficient compositions. • Sr-deficient SrTi 0.3 Fe 0.7 O 3−δ exhibits improved steam electrolysis performance. [ABSTRACT FROM AUTHOR]