Enhanced oxygen reduction kinetics by a porous heterostructured cathode for intermediate temperature solid oxide fuel cells

Abstract

A novel porous heterostructured Nd0.8Sr1.2CoO4±δ/Nd0.5Sr0.5CoO3-δ (NSC214/113) cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) is developed to significantly enhance oxygen reduction reaction (ORR) kinetics. Compared to single-phase materials, the fabricated porous heterostructured NSC214/113 shows optimized electrochemical properties, including a better conductivity, 20 times faster surface oxygen exchange kinetics, and a comparatively lower area-specific resistance (0.065 Ω cm2 at 800 °C). The single cell with Ni-YSZ|YSZ-GDC|NSC214/113 configuration exhibits a high peak power density of 1.10 W cm−2 at 800 °C, superior to other cells reported in literature with similar heterostructured cathodes. Moreover, the underlying mechanism of the ORR performance enhancement is further investigated, revealing that the formation of heterojunction can lead to a narrowed energy bandgap and a decrease of Co oxidation state, which further induce better conductivity, more available electrons and oxygen vacancies to enhance the ORR process. Taken together, our research also provides new insights into potential application of artificial intelligence (AI) method involved in materials intelligent identification, cell state estimation, system diagnostic and optimization. The revolutionary force of AI, especially in the field of new electrode material development is now advancing in its full swing. More and greater breakthroughs are still expected.

Keywords

• Heterostructure
• Oxygen reduction reaction (ORR)
• Intermediate temperature-SOFC
• Nd0.8Sr1.2CoO4±δ/Nd0.5Sr0.5CoO3-δ
• Energy bandgap
• Oxygen vacancy