Co and Hf co-doped BaFeO3 cathode with obviously enhanced catalytic activity and CO2 tolerance for solid oxide fuel cell

Abstract

It is essential to develop efficient and stable cathode materials operated at intermediate temperature for the application of solid oxide fuel cell. In this work, BaFeO3–δ based perovskite oxide was used to explore the influence of Co and Hf co-doping on the catalytic activity and CO2 tolerance of SOFC cathode materials. Among the series materials, BaCo0·2Fe0.7Hf0.1O3–δ (BC2FHO) shows excellent catalytic activity and CO2 stability. The EIS measurement shows that the polarization resistance (Rp) of BC2FHO is ∼0.04 Ω cm2 at 800 °C. In the CO2 tolerance test, the Rp decreases to ∼0.0435 Ω cm2 within 1 h after removing 10% CO2. The peak power density of the single cell with BC2FHO cathode are 1010.4, 649.4, and 256.6 mW cm−2 at 800, 700, and 600 °C, respectively. And the total degradation rate of the output voltage at 700 °C is only 0.009% h−1. The significantly enhanced activity and stability are attributed to Co and Hf co-doping. The incorporation of Hf allows BaFeO3 to obtain a highly symmetrical cubic structure with increased oxygen ion transport channels, which is conducive to promote the oxygen reduction reaction. In addition, Hf-doping can also increase the acidity to make the material resistant to CO2. The incorporation of Co improves the concentration of oxygen vacancies, which makes BC2FHO show excellent electrochemical performance.