Enhancing solid oxide electrolysis cell cathode performance through defect and bond engineering: A study on K-doped PrBaMn2O5+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 PrBaMn2O5+s (PBM) and Pr 0.9 K 0.1 BaMn 2 O 5+s (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 degrees C. This strategy provides valuable insights for designing advanced cathodes for high-temperature H2O electrolysis and other electrochemical catalysis applications.