A highly active and durable electrode with in situ exsolved Co nanoparticles for solid oxide electrolysis cells

This work demonstrates that a double perovskite Sr2Fe1.3Co0.2Mo0.5O6-delta (SFCM) with exsolved Co nanoparticles has enhanced the reaction activity and durability of solid oxide electrolysis cells (SOECs) for electrolysis of H2O, CO2 or CO2-H2O mixture. The Co nanoparticles are in situ exsolved from the parental SFCM in 10% H-2-90% N-2, as confirmed by analyses of XRD, XPS, TEM and SEM, and they can keep stable in the atmosphere of 50% CO2-50% H-2 or 50% CO2-50% CO. The cells with a configuration of SFCMLa0.8Sr0.2Ga0.83Mg0.17O3-delta (LSGM)parallel to SFCM demonstrate excellent electrochemical performances in electrolysis. For example, polarization resistances of the electrolyzer are as low as 0.24 Omega cm(2) in 50% H2O-50% H-2 under open-circuit voltage. In addition, the cells for CO2/H2O co-electrolysis at 800 ?C shows a reasonable durability at different current densities of 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 A cm(-2), and 1.0 A cm(-2) for similar to 110 h s. Electrochemical impedance spectroscopy and distributed relaxation time analysis indicates that electrode surface exchange and diffusion are the rate-limiting steps in the electrolysis of CO2/H2O, and the resistances of these steps can be significantly decreased by the in situ exsolved Co nanoparticles from SFCM electrode, thereby providing higher activity and better stability.