Iron stabilized 1/3 A-site deficient La–Ti–O perovskite cathodes for efficient CO2 electroreduction

Abstract

CO₂ electroreduction in solid oxide electrolysis cells is appealing for energy storage and CO₂ fixation. Highly active electrocatalysts with long-term operation stability are vital for the electrochemical process. Herein, novel 1/3 A-site deficient perovskite cathodes La_0.66Ti_1−xFe_xO_3−δ (x = 0.2, 0.3 and 0.4) without alkaline-earth elements are synthesized. Compared with Ni and Co, Fe cations demonstrate a unique role in the formation of such Ti-based perovskite structures. These cathodes show superior electrochemical performance to other reported perovskite-type cathodes, with a low polarization resistance of 0.16 Ω cm² at 1.4 V and 800 °C for CO₂ electroreduction. La_0.66Ti_0.8Fe_0.2O_3−δ exhibits stable electrochemical performance over 300 h with the current density maintained above 0.5 A cm⁻² and faradaic efficiency close to 100%, indicating that these La_0.66Ti_1−xFe_xO_3−δ perovskites are promising cathodes for CO₂ electroreduction. The kinetic process analysis reveals that the cathode can be activated by applied voltages and the rate limiting step is the electron transfer from the cathode to CO₂. Surface reconstruction with the electrochemically exsolved iron nanoparticles under applied voltages is observed and shows good electrocatalytic activity towards CO₂ electroreduction, indicating that the cathode activity could be tuned via electrochemical methods.