Exploring the impact of basicity and oxygen vacancy for efficient CO2 adsorption in solid oxide electrolysis cells

Abstract

A novel approach to boost the catalytic performance of cathode materials in solid oxide electrolysis cells (SOECs) is developed by modifying the oxygen ion basicity of the perovskite structures through strategic cation doping. In this study, Sr₂Fe_1.5-xCu_xMo_0.5O_6−δ (SFC_xM) perovskites are synthesized and systematically characterized to evaluate their oxygen ion basicity and electrocatalytic activity and assess their effects on the electrochemical performance. The Sr₂Fe_0.75Cu_0.75Mo_0.5O_6−δ (SFCu_0.75M) cathode demonstrates promising performance in experimental tests, achieving a current density of 0.91 A cm⁻² at 1.8 V and 850 °C, with stable operation over 100 h in a CO₂ atmosphere. These findings confirm that doping with higher-electronegativity ions, such as Cu, reduces the oxygen ion basicity, increases the oxygen vacancy concentration in the cathode, and enhances electrochemical performance. This approach provides crucial insights for engineering sophisticated electrodes suitable for direct carbon dioxide electrolysis and other catalytic electrochemical processes.