In-situ exsolution of cobalt nanoparticles from La0.5Sr0.5Fe0.8Co0.2O3-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 La0.5Sr0.5Fe0.8Co0.2O3-δ (LSFC82) to obtain La0.5Sr0.5Fe0.7Co0.2Nb0.1O3-δ (LSFCN721) and La0.5Sr0.5Fe0.8Co0.1Nb0.1O3-δ (LSFCN811), respectively. LSFC82-Sm0.2Ce0.8O2-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.