Surface oxygen vacancy regulation strategy enhances the electrochemical catalytic activity of CoFe₂O₄ cathode for...

Oxygen vacancies are crucial for enhancing oxygen ion transport in solid-state materials. Therefore, an approach was established to efficiently adjust the surface oxygen vacancy concentration in the solid oxide fuel cell (SOFC) cathodes. This method employs NaBH₄ solution to capture lattice oxygen on the cathode surface, enabling precise control over both the surface oxygen vacancy concentration and the transition metal ion valence states in spinel CoFe₂O₄ (CFO) by modulating the NaBH₄ treatment duration. The results indicate that CFO-10, treated with NaBH₄ solution for 10 min, exhibits optimal electrochemical catalytic activity. This enhancement is primarily attributed to the improved oxygen adsorption-dissociation and charge transfer processes. At 750 °C, CFO-10 shows a polarization resistance (Rp) of 0.032Ω cm², representing a reduction of 42.8 % compared to CFO. Additionally, CFO-10 achieves a peak power density (PPD) of 923 mW·cm^-2, representing a 78.5 % increase compared to CFO. This study provides new insights for optimizing SOFC spinel oxide cathode performance and opens a promising avenue for the development of other high-performance catalytic materials.