Fluorination Intensifying Oxygen Evolution Reaction for High-Temperature Steam Electrolysis

Solid oxide electrolysis cells (SOECs) have emerged as one of the most potent techniques for hydrogen production. As the restricted step for SOEC, as well as the most predominant obstacle to the scaled application, oxygen evolution reaction (OER) should be urgently accelerated by developing potent electrocatalysts. Despite inferior electrochemical activity to cobalt-based materials, perovskite ferrites exhibit great potential in the future with regard to good intrinsic stability and durability, abundant reserves, and good compatibility with other SOEC components. In this work, fluorination is introduced to the typical perovskite ferrite to further intensify the OER process. Ab initio calculations combined with physical- chemical characterizations are performed to reveal the mechanism. The doped F- leads to debilitating the strength of the metal-oxygen bond and then reduces the energy for oxygen vacancy formation and ion migration, which renders improvements to sub-processes of OER on the anode. The well-verified material, PrBaFe2O5+δF0.1 (PBFOF), exhibited a low polarization resistance of 0.058 ω cm-2. Single cells based on PBFOF showed a high current density of 2.28 A cm-2 at 750 °C under 1.3 V. This work provides a clear insight into the mechanism of fluorination on perovskites and high-activity anode material for SOEC.