CuCo₂O₄-Er_0.4Bi_1.6O_3-δ: An active hybrid cathode for intermediate temperature solid oxide fuel cells

The sluggish oxygen reduction reaction acts as a vital barrier to the performance enhancement for intermediate temperature solid oxide fuel cells. In this paper we report a CuCo₂O₄-Er_0.4Bi_1.6O_3-δ composite cathode synthesized via sol-gel and subsequent mechanical mixing methods. The composite cathode contains an electronic conductor CuCo₂O₄ and an ionic conductor Er_0.4Bi_1.6O_3-δ, dramatically enhancing the oxygen reduction reaction kinetics and the sintering performance. Introduction of the Er_0.4Bi_1.6O_3-δ nanoparticles brings an obvious increase of triple phase boundaries and enhancement of electrochemical activities. As expected, the composite cathode with addition of 35 wt% of Er_0.4Bi_1.6O_3-δ shows the least polarization resistance of 0.07 Ω cm² in air at 800 °C. What's more, the sintering temperature is distinctly reduced from 1000 °C to 800 °C.