Enhanced CO2 electrolysis performance of medium-entropy perovskite cathode through in situ exsolution of Co nanoparticles

Abstract

To reduce CO₂ emissions and promote the use of sustainable energy, solid oxide electrolysis cell (SOEC) technology can effectively convert CO₂ into CO, and the choice of cathode material has a crucial impact on the electrolysis performance. In this work, we prepare a novel medium-entropy perovskite cathode material Pr_0.4Ba_0.2Ca_0.2La_0.2Co_0.2Fe_0.8O₃ (PBCLCF) and further improve its catalytic performance through the in situ exsolution strategy. After reduction at 700 °C, Co nanoparticles are adhered to the surface of the PBCLCF perovskite matrix. The electrolysis performance results reveal that when the reduced PBCLCF is used as the cathode, the current density of the single cell reaches ∼1700 mA·cm^-2 at 800 °C/1.5 V for CO₂ electrolysis, which is 1.41 times the electrolysis performance of the single cell using PBCLCF as the cathode. Subsequently, when the reduced PBCLCF is used as the cathode for co-electrolysis of 30%H₂O-70%CO₂, the current density of the single cell at 800 °C/1.5 V reaches ∼1900 mA·cm^-2, which is 46% higher than that of the single cell using PBCLCF as the cathode. Furthermore, after 45 h stability test, no significant performance degradation is observed for both CO₂ electrolysis and H₂O-CO₂ co-electrolysis. The exsolution of Co nanoparticles effectively improve the CO₂ adsorption capacity and enhance the concentration of oxygen vacancy, thereby improving the oxygen migration capacity of PBCLCF and promoting the progress of electrochemical reduction reaction. This work provides new insights for the design and development of novel cathode materials for SOEC.