La0.6Sr0.4Fe0.8Ni0.2O3-δ perovskite with in-situ exsolved Ni-Fe nanoparticles as high activity catalyst for symmetric solid oxide electrolysis cells

Abstract

• FeNi 3 nanoparticles were in-situ exsolved on the surface of the perovskite after treatment. • LSFN have excellent oxygen ion transport capability as air electrodes in an oxidizing atmosphere. • Reduced LSFN have high catalytic activity as fuel electrodes in a reducing atmosphere. Effective electrode materials play a key role to enhance electrochemical performances of symmetric solid oxide electrolysis cells (SSOECs). Herein, “exsolution effect” of perovskite oxide at high temperature and reducing atmosphere is introduced. As a proof, La 0.6 Sr 0.4 Fe 0.8 Ni 0.2 O 3-δ (LSFN) perovskite decorated with in-situ exsolved Ni-Fe alloy nanoparticles is reported as electrode materials of SSOECs. XRD, SEM, TEM, and XPS characterizations prove the formation of Ni-Fe alloy. The as-prepared SSOECs deliver improved electrochemical performances for both steam electrolysis (50%H 2 O/50%H 2 ) and co-electrolysis (50%H 2 O/40%CO 2 /10%H 2 ), current densities of 0.64 and 0.67 A·cm −2 are obtained at 1.3 V and 800°C, respectively. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis show that the in-situ formed Ni-Fe nanoparticles can provide a new reaction path for water/hydrogen half-reaction, and electrochemical activity and kinetics of oxygen evolution reaction (OER) can be significantly enhanced by RP type perovskite oxide after re-oxidation treatment. Moreover, the SSOECs successfully runs for 60 h at 1.2 V without obvious attenuation.