Pr2BaNiMnO7−δ double-layered Ruddlesden–Popper perovskite oxides as efficient cathode electrocatalysts for low temperature proton conducting solid oxide fuel cells

Abstract

The performance of low-temperature solid-oxide fuel cells (LT-SOFCs) is heavily dependent on the electrocatalytic activity of the cathode toward the oxygen reduction reaction (ORR). To overcome the obstacles of the poor activity and stability of traditional cathode materials, a Pr₂BaNiMnO_7−δ double-layered Ruddlesden–Popper structural oxide was developed that exhibits high ORR activity, exceptional low-temperature cell performance, long-term stability, and excellent chemical compatability with a BaZr_0.1Ce_0.7Y_0.1Yb_0.1O_3−δ (BZCYYb) proton-conducting electrolyte. When Pr₂BaNiMnO_7−δ is used as the cathode electrocatalyst for BZCYYb-based SOFCs, it demonstrates a peak power density of 1070 mW cm⁻² at 700 °C with excellent stability under 0.7 V after 100 h of discharging. Even at 500 and 400 °C, the peak power densities still reach 259 and 135 mW cm⁻², respectively. The area-specific polarization resistance of this cell is 0.084 Ω cm² at 700 °C under open-circuit voltage (OCV) conditions. Interestingly, the activation energy (E_a) of the polarization resistance derived from the assembled single cell is lower than that in the reported literature, corresponding to a value of 0.96 eV. The excellent performance is higher than those of the state-of-the-art Ruddlesden–Popper structure materials used as cathode electrocatalysts for LT-SOFCs. Thus, these results suggest that the double-layered Ruddlesden–Popper perovskite oxide Pr₂BaNiMnO_7−δ is a preeminent highly active low-temperature cathode material.