Investigating the role of Cu-doping and A-site deficiency in enhancing CO2 electrolysis performance of Ruddlesden-Popper structured fuel electrodes

Abstract

Solid oxide electrolysis cells (SOECs) are becoming a promising technology that can convert CO₂ into available fuels. However, issues such as deactivation of the fuel electrode material at high temperatures, low catalytic activity for the CO₂ reduction reaction (CO₂RR), and poor durability have restricted the development of the SOEC. In this study, we propose a strategy of Cu doping and A-site deficiency and prepared Ruddlesden-Popper (R-P) structured perovskite PrSrFeO₄ (PSF), Pr_1.0Sr_1.0Fe_0.75Cu_0.25O₄ (PSFCu), and (PrSr)_0.9Fe_0.75Cu_0.25O_4-δ (PSFCu90) as high-performance fuel electrode materials. The synergistic effect of B-site Cu doping and A-site deficiency increases oxygen vacancy concentration, facilitates oxygen ion migration and provides additional adsorption sites for CO₂, thereby, enhancing the catalytic activity for CO₂RR. The results show that the current density of the single cell with PSFCu90 as the fuel electrode is 0.62 A cm⁻² at 1.5 V/800 °C in electrolysis mode and the maximum power density (P_max) is 0.11 W cm⁻² in discharge mode with 50 %CO–50 %CO₂ as the fuel gas. For the electrolysis of pure CO₂, the current density can reach 1.82 A cm⁻² and exhibit an excellent stability over 600 min without any significant degradation at 800 °C/1.5 V. Therefore, the R-P structured perovskite controlled by Cu doping and A-site deficiency is considered as a promising high-performance fuel electrode material.