Highly efficient perovskite-based fuel electrodes for solid oxide electrochemical cells via in-situ nanoparticle exsolution and electron conduction enhancement

Developing efficient fuel catalysts exhibiting high electrocatalytic activity and stability is crucial to improving the performance of solid oxide fuel/electrolysis cells for electrochemical energy storage and conversion. The oxide catalysts have been extensively investigated for replacing conventional Ni-based fuel electrodes, owing to their excellent stability and high resistance to coking in the presence of carbon-based fuels, such as during CO₂ electrolysis. In this study, we propose a novel strategy to enhance the oxide electrocatalyst performance via nanoparticle exsolution and electron conduction improvement. In this strategy, the A-site deficient Sr_0.95Ti_0.3(Fe_0.9Ru_0.1)_0.7O_3-δ (STFR) was coupled with Sr₂Fe_1.5Mo_0.5O_6-δ (SFM) to yield a composite electrode. STFR with in-situ exsolved Fe–Ru nanoparticles provided high catalytically active sites, whereas SFM increased the electron conduction pathways, further boosting the electrode activity. When the composited electrodes were applied to an LSGM electrolyte-supported cell, the Fe–Ru exsolved STFR–SFM exhibited superior activity, surpassing those of previously reported performance metrics, including >1.5 W cm⁻² peak power density in fuel cell mode, >1.75 A cm⁻² (at 1.3 V) in the steam electrolysis mode, and >2.15 A cm⁻² (at 1.3 V) in direct CO₂ electrolysis mode at 800 °C. The composite electrode demonstrates excellent electrochemical catalytic activity, remarkable durability, and preferential selectivity toward CO₂ electrolysis.