In-situ exsolution of cobalt nanoparticles from La_0.5Sr_0.5Fe_0.8Co_0.2O_3-δ cathode for enhanced CO₂ electrolysis performance

Solid oxide electrolysis cell (SOEC) is a promising technology for CO₂ conversion and renewable energy storage with high efficiency. It is highly desirable to develop catalytically active cathodes for CO₂ electrolysis. Herein, cathode materials with different structural stabilities are designed by Nb substitution on La_0.5Sr_0.5Fe_0.8Co_0.2O_3-δ (LSFC82) to obtain La_0.5Sr_0.5Fe_0.7Co_0.2Nb_0.1O_3-δ (LSFCN721) and La_0.5Sr_0.5Fe_0.8Co_0.1Nb_0.1O_3-δ (LSFCN811), respectively. LSFC82-Sm_0.2Ce_0.8O_2-δ (SDC) cathode with inferior structural stability (ability to maintain the structure) shows desirable CO₂ electrolysis performance with the generated current density of 1.80 A cm⁻² at 1.6 V and stable performance during 110 h operation at 1.2 V and 800 °C. However, LSFC82 particles are collapsed into pieces after stability test with the generation of Co nanoparticles simultaneously. The frameworks of LSFCN721 and LSFCN811 particles maintain well because of the high-valent niobium, but Co exsolution, oxygen vacancy content and the corresponding CO₂ electrolysis performance are restricted. This work confirms that Co nanoparticles can be exsolved from LSFC82-SDC cathode during CO₂ electrolysis, providing references for constructing metallic nanoparticles decorated-perovskite cathodes for SOECs.