Redox-reversible perovskite ferrite cathode for high temperature solid oxide steam electrolyser

In this work, perovskite Sr1-xPrxFeO3-delta (SPF) (x=0.02, 0.04, 0.06, 0.08 and 0.10) are investigated and employed as solid oxide steam electrolyser cathode at 800 degrees C. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM) analysis together indicate that the Sri,PrxFeO3-delta is redox reversible with a phase transition from cubic to orthorhombic structure in redox cycles. The doping of Pr in A site has remarkably enhanced the electronic conduction to 1.0-1.2 S cm(-1) at intermediate temperatures in reducing atmosphere. Electrochemical measurements demonstrate that the polarization resistance with Sr0.96Pr0.04FeO3-delta electrode shows the lowest values of 0.25 Omega, cm(2) in symmetric cells in reducing atmosphere at 800 degrees C. Direct steam electrolysis with Sr0.96Pr0.04FeO3-delta cathode shows a current density of 1.64 A cm(-2) at 2.0V when fed with 5%/H2O/Ar. The hydrogen production rate reaches 4.73, 6.68, 835 and 10.23 mL min(-1) cm(2) at 1.4,1.6, 1.8, 2.0V, respectively, while the highest Faraday efficiency is as high as 97.16% at 1.8 V. (C) 2017 Elsevier Ltd. All rights reserved.