Highly active and stable A-site Pr-doped LaSrCrMnO-based fuel electrode for direct CO2 solid oxide electrolyzer cells

Abstract Direct CO2 electrolysis has been explored as a means to store renewable energy and produce renewable fuels. La chromate-based perovskite oxides have attracted great attention as fuel electrode materials for solid oxide electrolyzer cells. However, the electrochemical catalytic activity of such oxides is relatively low, and their stability has not been confirmed. In this study, Pr is doped into La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) and the applicability of the resulting fuel electrode to direct CO2 electrolysis is investigated. The polarization resistance of the resulting electrode at 800 °C is decreased by 25%. Distribution function of relaxation times analysis indicates that the observed improvements may be attributed to increased oxygen ion conductivity. A full cell of Pr-doped LSCM-gadolinium-doped ceria (GDC)|scandia-stabilized zirconia|La0.6Sr0.4Co0.2Fe0.8O3-δ-GDC achieves an electrolysis current of 0.5 A cm−2 at 1.36 V and a Faradaic efficiency close to 100%. Short-term (210 h) stability testing of the cell under an electrolysis current of 0.5 A cm−2 at 800 °C with pure CO2 as the feedstock reveals a decrease in applied voltage at a rate of 7 mV kh−1, thereby indicating excellent stability. Thus, given its satisfactory performance and stability, the Pr-doped LSCM electrode may be considered a promising candidate material for direct CO2 electrolysis.