Enhanced Activity of Pr₆O₁₁ and CuO Infiltrated Ce_0.9Gd0.₁O₂ Based Composite Oxygen Electrodes

Operation of solid oxide fuel/electrolysis cells (SOFC/SOEC) at high temperatures (T > 850 °C) is accompanied by degradation phenomena, which severely affect the operational lifetime of the cell. Degradation processes are expected to occur slower at low temperatures. However, significant reduction in electrocatalytic activity of the oxygen electrode, is one of the major challenges in decreasing the operating temperature down to 500 °C–650 °C. Recently, Pr6O11 infiltrated Ce0.9Gd0.1O2 (CGO) based electrodes have been proposed to realize high electrochemical performance at intermediate temperature. In this study, Pr-oxide has been infiltrated into a well performing sub-micro La0.6Sr0.4Co0.2Fe0.8O3/Ce0.9Gd0.1O2 (LSCF/CGO) composite electrode as well as a poorly performing LaNi0.6Fe0.4O3/Ce0.9Gd0.1O2 (LNF/CGO) electrode. The results are compared with Cu-oxide infiltration. Formation of Pr rich oxide surface nanostructures, resulted in a pronounced reduction of polarization resistances by a factor of 3 in state of the art LSCF/CGO electrodes. Even better performances were achieved in Pr6O11 infiltrated LNF/CGO, demonstrating low polarization resistances of 0.074 ∓ 0.002 and 0.146 ∓ 0.002 Ω.cm2 at 600 °C and 550 °C, respectively. Low degradation rates were observed over a 200 h durability test at 650 °C, illustrating the potential of Pr6O11 infiltrated CGO oxygen electrodes for intermediate temperature SOFC/SOEC application.