Layered-perovskite oxides with in situ exsolved Co-Fe alloy nanoparticles as highly efficient electrodes for high-temperature carbon dioxide electrolysis

Carbon dioxide (CO2) reduction using solid oxide electrolysis cells (SOECs) has attracted great attention because of the high efficiency and fast kinetics enabled by high operating temperatures. Electrode materials with high catalytic activity for CO2 reduction and good stability over long-term operation, nevertheless, are still to be developed. In this work, layered-perovskite oxide electrodes with in situ exsolved Co-Fe alloy nanoparticles are developed for efficient CO2 electrolysis to produce carbon monoxide (CO). Using double perovskite oxide Sr2Ti0.8Co0.2FeO6-delta as a solid precursor, a Ruddlesden-Popper phase oxide matrix with exsolved Co-Fe alloy nanoparticles uniformly distributed on the surface (Co-Fe-STCF) is synthesized by thermal reduction. The cell with a mixture of Co-Fe-STCF and Sm0.2Ce0.8O2-delta (SDC) as the fuel electrode exhibits outstanding performance for CO2 electrolysis, with a polarization resistance (R-p) as low as 0.22 omega cm(2) at 800 degrees C. A current density of 1.26 A cm(-2) is acquired at a bias of 1.6 V at 800 degrees C, and the CO production rate reached 8.75 mL min(-1) cm(-2) with a high value of Faraday efficiency (similar to 100%). Moreover, the Co-Fe-STCF-SDC electrode shows good stability for long-term (100 h) operation with no carbon deposition on the surface. Such high performance of the Co-Fe-STCF-SDC electrode is attributed to abundant oxygen vacancies in the oxide matrix and the high catalytic activity of the exsolved metal nanoparticles. The result of this work can guide the design of highly active and stable (electro)catalysts for high-temperature energy and environmental devices.