Enhancing solid oxide electrolysis cell cathode performance through defect and bond engineering: A study on K-doped PrBaMn₂O_5+δ perovskites

Collaborative design of defects and bonds is a novel strategy to enhance the activity of cathode materials for solid oxide electrolysis cells (SOECs). In this study, we report the synthesis and characterization of layered PrBaMn₂O_5+δ (PBM) and Pr_0.9K_0.1BaMn₂O_5+δ (PKBM) materials, aimed at developing cathodes for high-temperature H₂O electrolysis. The effects of K doping on the structural, physicochemical, and electrochemical properties of these materials are thoroughly investigated. The results reveal that K doping induces lattice expansion and reduces the total cation valence state in PKBM. These changes significantly increase oxygen vacancy concentration, enhancing the chemical adsorption capacity of H₂O on the electrode surface and improving the H₂O reduction reaction activity. Theoretical calculations support these findings, showing that K doping lowers the oxygen vacancy formation energy and strengthens H₂O adsorption. Impedance analyses further demonstrate that K doping reduces the polarization resistance, thereby enhancing surface adsorption and diffusion processes. Consequently, the PKBM cathode exhibits superior electrolysis performance, achieving a current density of 739 mA/cm² at 1.3 V and 800 °C. This strategy provides valuable insights for designing advanced cathodes for high-temperature H₂O electrolysis and other electrochemical catalysis applications.