Electrochemical performance of La_0.8Sr_0.2MnO₃ oxygen electrode promoted by Ruddlesden‐Popper structured La₂NiO₄

Abstract

The effects of introducing La2NiO4 nanocatalyst on the electrochemical performance of La0.8Sr0.2MnO3 are investigated under solid oxide electrolysis cell and fuel cell modes, as well as open circuit voltage. Extracted data from impedance spectroscopy are interpreted with the analysis of distribution of relaxation times. La2NiO4 infiltration effectively reduces the activation energy of the oxygen reactions from 1.35 to 0.99 eV. It also changes the rate controlling process of the overall reaction. Polarization behavior of La2NiO4‐infiltrated La0.8Sr0.2MnO3 electrode shows superior performance under electrolysis mode compared to the fuel cell mode. Drastic increase in the size of low frequency arc during anodic current passage in the non‐infiltrated La0.8Sr0.2MnO3 electrode is hampered by infiltration of La2NiO4 nanocatalyst. By applying anodic current on infiltrated La0.8Sr0.2MnO3, no displacement is observed in the position of high frequency peaks in the distribution of relaxation time graphs and only a small increase in height occurs for the low frequency arc. Additionally, La2NiO4‐infiltrated electrode impressively decreases overpotential by 74% compared to the non‐infiltrated one under electrolysis mode at 800°C.