Optimizing CO2 Electrolysis Performance on Oxygen Vacancy Modulation for LaxSr2–xTiFeO6 Perovskite in a Solid Oxide Electrolysis Cell

In order to exploit cost-effective and sustainable solid oxide electrolysis cell (SOEC) devices, the selection of efficient and durable fuel electrodes for the application is crucial. Herein, the improvement of the carbon dioxide (CO₂) electrolysis performance for La_xSr_2–xTiFeO₆ (L_xSTF, where x = 0, 0.1, 0.2, and 0.3) double perovskite is studied on oxygen vacancy modulation. La doping not only causes lattice expansion in cubic phase perovskite oxides but also significantly increases the content of surface oxygen species. Compared to the original Sr₂TiFeO₆ (STF) perovskite oxide, the concentration of oxygen vacancies and CO₂ adsorption capacity of the La_0.1Sr_1.9TiFeO₆ (LSTF01) material are significantly improved. Based on electrochemical analysis, the doping of La element promotes the oxygen-ion conduction process and facilitates CO₂ adsorption during the CO₂ reduction reaction (CO₂RR), which results in the lowest polarization resistance (R_p) value of 0.70 Ω·cm² at open-circuit voltage and the highest peak current density of 0.95 A·cm^–2 at 800 °C for the LSTF01 material. This work provides a highly effective strategy to modulate oxygen vacancies for optimization of the fuel electrode material for SOEC.