カチオン添加による酸素活性の調節と高温二酸化炭素電解効率の向上

High-temperature solid oxide electrolysis cells (SOECs) offer a promising pathway for CO₂-to-CO conversion yet are hindered by cathode inactivity. This study demonstrates cation doping in Sr₂Ti_0.8Fe_1.2O_6-δ (STF), specifically forming Sr₂Ti_0.8FeNi_0.2O_6-δ (STFN) and Sr₂Ti_0.8FeCo_0.2O_6-δ (STFC), as an effective strategy for modulating oxygen activity and enhancing CO₂ electrolysis performance. The STFC cathode delivers optimal results, achieving a 1.15 A cm^-2 current density, 8.01 mL min^-1 cm^-2 CO production rate, and >99% Faradaic efficiency at 1.6 V and 800 °C. Advanced spectroscopic techniques combined with density functional theory calculations reveal that Co doping increases oxygen activity, evidenced by an upshifted O 2p band center and reduced oxygen vacancy formation energy. Consequently, CO₂ adsorption for carbonate (CO₃^2-) intermediate formation is facilitated, and the energy barrier for CO generation is reduced. A techno-economic assessment projects a competitive CO production cost of $748 per ton. These insights provide fundamental guidelines for the design of high-activity catalysts in high-temperature electrochemical systems.