Composite ceramic cathode La0.9Ca0.1Fe0.9Nb0.1O3-δ/Sc0.2Zr0.8O2−δ towards efficient carbon dioxide electrolysis in zirconia-based high temperature electrolyser

In this paper, a novel composite La0.9Ca0.1Fe0.9Nb0.1O3-δ/Sc0.2Zr0.8O2−δ (LCFNb/ScSZ) is developed and investigated as a fuel electrode candidate for direct electrolyzing carbon dioxide (CO2) in solid oxide electrolysis cells (SOECs). XRD patterns of LCFNb powder sintered in CO2 at 850 °C for 10 h indicate that no secondary phases are found during the heat treatment and linear thermal expansion results prove that the LCFNb is compatible with ScSZ electrolyte used in this work. The electrolyser with porous LCFNb membrane cathode fabricated by infiltration method shows impressive electrochemical performance. The current density of 1.97 A/cm2 at 2.0 V at 800 °C is obtained. The polarization resistance Rp of the SOEC decreases with the increase of the applied voltage between the electrodes. The obtained lowest Rp is as low as 0.113 Ω cm2 at 2.0 V and this value is much lower than its many other perovskite and nickle-based counterparts. Besides, the LCFNb/ScSZ cathode shows excellent stability in pure CO2 at different applied voltage, especially at 2.0 V. Furthermore, the LCFNb/ScSZ electrode exhibits the current efficiencies close to theoretical ones for CO2 electrolysis, indicating that the LCFNb/ScSZ composite ceramic is an excellent cathode for zirconia-based high temperature electrolyser.