CO₂-induced in-situ surface reconfiguration of strontium cobaltite-based perovskite for accelerated oxygen reduction reaction

For solid oxide fuel cells, it is an effective strategy to enhance the oxygen reduction reaction activity of cathode through introducing active nanoparticles on electrode surface. In this study, we developed a novel cathode SrY_0.05W_0.05Co_0.9O_3-δ and optimizing strategy of CO₂-induced surface in-situ reconfiguration. The nanoscale SrCO₃ particles and the oxide nanoparticles could be produced after the treating atmosphere was switched from CO₂ to air. Both SrCO₃ nanoparticles and nano-oxides are beneficial to the oxygen reduction reaction kinetics of surface process and the area specific resistance of symmetric cell with SrY_0.05W_0.05Co_0.9O_3-δ electrode decreased from 0.085 to 0.054 Ω cm² at 600 ℃. Although the nano-sized SrCO₃ was degraded in air over time, the oxide nanoparticles held a stable state for a long time and the resistance finally stabilized at ∼0.068 Ω cm². However, for classic cathode Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ, it possesses a strong interaction with CO₂ so that the produced large-sized BaCO₃ failed to transform into nanoparticles and totally decompose. Therefore, designing the suitable cathode and tailoring the interaction between CO₂ and electrode materials are significant to realize the CO₂-induced surface in-situ reconfiguration.