Lewis Basicity Enhanced SrFeO-Based Perovskite Fuel Electrode for Surface and Bulk Processes Co-Accelerated CO Reduction in Solid Oxide Electrolysis Cells.

Electroreduction of CO 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 (Cs) is employed to develop a series of perovskite-type fuel electrode materials, i.e., CsSrFeNbO (x = 0.05, 0.1, 0.15). Combining the results of experiments and theoretical calculations, it is found that the introduction of Cs into A-site of SrFeO-based perovskite accelerates the reaction kinetics of CO adsorption and dissociation due to increased lattice oxygen basicity caused by the low electronegativity of Cs. In addition, in comparison to Sr, the larger ionic radius and lower valence of Cs is beneficial to decrease formation energy of oxygen vacancy and migration barrier of oxygen ion in perovskite bulk. Because of those merits brought by Cs doping, the LaSrGaMgO electrolyte-supported electrolysis cells with CsSrFeNbO fuel electrode presents satisfied current density of 2205 mA cm 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 and 800 °C for 100 h.