Lewis Basicity Enhanced SrFeO3-δ-Based Perovskite Fuel Electrode for Surface and Bulk Processes Co-Accelerated CO2 Reduction in Solid Oxide Electrolysis Cells

Electroreduction of CO2 to CO by solid oxide electrolysis cells (SOEC) is an effective means to realize carbon neutralization. However, the sluggish kinetics at SOEC fuel electrode impedes its further practical application. Herein, the doping strategy of cesium ion (Cs1+) is employed to develop a series of perovskite-type fuel electrode materials, i.e., CsxSr1-xFe0.9Nb0.1O3-δ (x = 0.05, 0.1, 0.15). Combining the results of experiments and theoretical calculations, it is found that the introduction of Cs1+ into A-site of SrFeO3-δ-based perovskite accelerates the reaction kinetics of CO2 adsorption and dissociation due to increased lattice oxygen basicity caused by the low electronegativity of Cs1+. In addition, in comparison to Sr2+, the larger ionic radius and lower valence of Cs1+ is beneficial to decrease formation energy of oxygen vacancy and migration barrier of oxygen ion in perovskite bulk. Because of those merits brought by Cs1+ doping, the La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte-supported electrolysis cells with Cs0.1Sr0.9Fe0.9Nb0.1O3-δ fuel electrode presents satisfied current density of 2205 mA cm-2 at 1.6 V and 850 °C. The stable long-term operation of electrolysis cells is also demonstrated at applied current density of 600 mA cm-2 and 800 °C for 100 h.Electroreduction of CO2 to CO by solid oxide electrolysis cells (SOEC) is an effective means to realize carbon neutralization. However, the sluggish kinetics at SOEC fuel electrode impedes its further practical application. Herein, the doping strategy of cesium ion (Cs1+) is employed to develop a series of perovskite-type fuel electrode materials, i.e., CsxSr1-xFe0.9Nb0.1O3-δ (x = 0.05, 0.1, 0.15). Combining the results of experiments and theoretical calculations, it is found that the introduction of Cs1+ into A-site of SrFeO3-δ-based perovskite accelerates the reaction kinetics of CO2 adsorption and dissociation due to increased lattice oxygen basicity caused by the low electronegativity of Cs1+. In addition, in comparison to Sr2+, the larger ionic radius and lower valence of Cs1+ is beneficial to decrease formation energy of oxygen vacancy and migration barrier of oxygen ion in perovskite bulk. Because of those merits brought by Cs1+ doping, the La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte-supported electrolysis cells with Cs0.1Sr0.9Fe0.9Nb0.1O3-δ fuel electrode presents satisfied current density of 2205 mA cm-2 at 1.6 V and 850 °C. The stable long-term operation of electrolysis cells is also demonstrated