Enhancing the steam electrolysis by simultaneously regulating the electron and oxygen ion conductivity of la1-xsr1+xfeo4-δ oxides

Abstract

Ruddlesden-Popper (RP) La1-xSr1+xFeO4-δ(x = 0,0.2,0.4) oxides with different Sr content are investigated as air electrodes for solid oxide electrolytic cells. The increased Sr content in La1-xSr1+xFeO4-δ significantly improves the electronic and oxygen ionic conductivity, enhancing the oxygen evolution reaction (OER) activity and electrochemical performance of steam electrolysis. The polarization resistance of the La0.8Sr1.2FeO4-δ symmetrical cell reaches 1.04 Ω cm2 at 800 °C, and the electrolysis cell delivers a current density of −1709 mA cm−2 at 1.3 V, corresponding to the hydrogen production rates of 714 ml/(cm2 h). Moreover, adding Sm0.2Ce0.8O2-δ (SDC) oxide further improves the steam electrolysis performance due to enhanced three-phase boundary active sites. The electrolysis cell with La0.8Sr1.2FeO4-δ-SDC electrode exhibits excellent stability for over 200 h and cycling durability for 100 h under 750 °C and 1.2 V in 50%H2O–H2 condition.