Comparative study on the electrochemical performance of Sr(Ti0.3Fe0.7)O3-δ fuel electrode in different fuel gases for solid oxide electrochemical cells

Sr(Ti_1-xFe_x)O_3?δ (STF) perovskite has been developed as one of the alternatives to Nickel-base fuel electrodes for solid oxide electrochemical cells (SOCs) that can provide good tolerance to redox cycling and fuel impurities. Recent results on STF fuel electrodes present excellent electrochemical performance and outstand stability both under H₂ fuel cell mode and H₂O electrolysis mode, however, the electrochemical characteristics in other fuel gases, such as CO, CO–H₂ mixture, CH₄, and CO–CO₂ mixture have not been investigated. Herein, we report the electrochemical performance of Sr(Ti_0.3Fe_0.7)O_3?δ fuel electrode on La_0.8Sr_0.2MnO_3?δ-Zr_0.92Y_0.16O_2?δ (LSM-YSZ) oxygen electrode supported SOCs with thin YSZ electrolyte using different fuel gases. At 800 °C, the peak power density slightly decreased from 0.9 W/cm² in wet H₂ to 0.68 W/cm² in wet CO under fuel cell mode. However, the cell only showed a peak power density of 0.27 W/cm² at 800 °C in wet CH₄, reaching 0.75 W/cm² at 850 °C, when the open-circuit voltage increased from 0.9 V to 1.02 V. STF fuel electrode exhibited much worse CO₂ electrolysis performance than steam electrolysis, especially in high CO₂ concentration due to the increased ohmic resistance and electrode polarization resistance.