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 LaxSr2-xTiFeO6 (LxSTF, 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 La0.1Sr1.9TiFeO6 (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 (Rp) 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.