CO2-to-CO conversion on layered perovskite with in situ exsolved Co-Fe alloy nanoparticles: an active and stable cathode for solid oxide electrolysis cells

To reduce the greenhouse effects due to the massive emission of CO2, efficient reduction of carbon footprint and effective utilization of CO2 have been a crucial research field worldwide in the past few decades. Novel catalysts efficiently facilitating the conversion of CO2 into target chemicals are highly desirable. Herein, we developed a new cathode with in situ exsolved Co-Fe alloy nanoparticles embedded in an active (Pr0.4Sr0.6)(3)(Fe0.85Mo0.15)(2)O-7 (PSFM) double-layered perovskite backbone (Co-Fe-PSFM), which acts as a more stable and efficient catalyst to promote CO2 electrolysis in a high temperature solid oxide electrolysis cell (SOEC) compared to the Pr0.4Sr0.6Co0.2Fe0.7Mo0.1O3-delta (PSCFM) cubic perovskite. This newly developed material shows superb redox reversibility between reduction and re-oxidation cycles. Additionally, a remarkable current density of 1.01 A cm(-2) of the SOEC with the Co-Fe-PSFM cathode in conjunction with an impressive polarization area-specific resistance (ASR) as low as 0.455 Omega cm(2) of the cathode was achieved at 1.6 V and 850 degrees C. In particular, a high value of Faraday efficiency (similar to 93%) was achieved at 0.8 V (vs. OCV) and 850 degrees C. More importantly, the cell with the new cathode shows no observable degradation and carbon formation at 850 degrees C over a period of 100 h at a constant applied potential. The improved oxygen vacancies resulted from the exsolving process, and phase change (cubic perovskite to double-layered perovskite), together with the exsolved Co-Fe alloy nanoparticles, contributed to the improved catalytic activity, high Faraday efficiency, good stability, and excellent coking resistance for CO2 electrolysis. In light of the properties above, double-layered PSFM socketed with Co-Fe alloy nanoparticles is an attractive ceramic material for intermediate/high temperature applications, especially for CO2 electrolysis.