Stability Study of Doped-PrCoO3 Perovskites as Oxygen Electrodes in Proton Conducting Electrolysis Cells

Within the field of electrochemical systems, perovskite oxides are notable for their high catalytic activity, particularly when they are rich in oxygen vacancies. These materials exhibit oxygen vacancies that have a dual function. These vacancies can enhance targeted reactions by acting as active sites, thereby boosting the overall efficacy of the system. Conversely, they may also initiate a sequence of adverse reactions that weaken the material’s structure and reduce its stability, especially at high temperatures or exposure to high concentration steam or CO 2 , like the typical operation conditions in proton conducting electrolysis cells (PCECs). Although these materials are widely used as oxygen electrodes in PCECs, the specific structural mechanisms that determine their stability under operation conditions are not well understood. In this work, we employed layered double perovskite PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ and rhombohedral perovskite PrNi 0.7 Co 0.3 O 3+δ to assess their structural stability. The challenging environments of high temperatures and exposure to high concentration steam accelerate potential structural degradation. Through density functional theory calculations and in situ Fourier transform infrared spectroscopy characterization, we demonstrate how lattice octahedra adapt to operational conditions, leading to anisotropic lattice stress and facilitating elemental segregation in different octahedral configurations. Our investigation delves into the atomic-scale intricacies of perovskite oxides, aiming to dissect the interplay between their structure and stability. This understanding could pave the way for developing more robust and effective materials.