The electrochemical performance and CO2 reduction mechanism on strontium doped lanthanum ferrite fuel electrode in solid oxide electrolysis cell

Abstract Carbon dioxide reduction reaction on the fuel electrode is critical for CO 2 conversion in solid oxide electrolysis cell, which is a promising technology to utilize CO 2 and store electricity from intermittent renewable resources. This work presents a highly active electrocatalyst, strontium doped lanthanum ferrite (LSF), for direct CO 2 reduction reaction, which is conducted in single cells with La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3 as the electrolyte and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ as the air electrode. A current density of 0.76 A cm −2 is achieved at 800 °C and 1.5 V when pure CO 2 is electrolyzed. By adding samaria-doped ceria to form composite fuel electrodes, the performance can be effectively improved. The current density increases from 0.76 to 1.06 A cm −2 while the total interfacial polarization resistance decreases from 0.26 to 0.12 Ω cm 2 . Furthermore, LSF exhibits high rate constant for CO 2 reduction reaction, 1.04 × 10 −4  cm s −1 at 700 °C. CO 2 is favorable to form carbonate species on LSF surface, and the existence of carbonate species on LSF surface revealed by Raman spectra technique is further proved by DFT calculations. A proposed CO 2 reduction mechanism is obtained, providing new insights into CO 2 adsorption and dissociation on LSF surface.