A highly active and stable cobalt-free Iron-based perovskite cathode for solid oxide electrochemical cells

The limited activity and durability of iron-based perovskite electrodes have significantly hindered their application in solid oxide electrochemical cells (SOCs). Herein, Mn and P co-doped SrFe_0.9-xMn_0.1P_xO_3-δ (SF_0.9-xM_0.1P_x, x = 0, 0.05, 0.10, 0.15) perovskites were prepared and systematically investigated as cathode materials for both solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs). The results demonstrate that Mn and P co-doping effectively regulates the grain size of SrFeO_3-δ (SF) materials, promotes the generation of oxygen vacancies, and enhances the adsorption and dissociation of oxygen, thus significantly improving the electrochemical performance. At 800 °C, SFM_0.1P_0.1 exhibited an R_p of 0.078 Ω cm², representing a 43.48 % reduction compared to SF, while its output performance improved by 140.43 %, reaching 938.02 mW cm^-2. The SOEC cell with the SFM_0.1P_0.1 electrode demonstrated excellent CO₂ electrolysis capabilities, achieving a current density of 1.73 A cm^-2 at 800 °C and 1.5 V. Furthermore, both SOFC and SOEC cells incorporating the SFM_0.1P_0.1 electrode exhibited outstanding performance stability. These findings suggest that co-doping with metal and non-metal cations serves as a promising approach to improve the electrode performance for both SOFCs and SOECs.