Despite recent substantial progress in reversible protonic ceramic cells (RPCCs) it remains essential to further develop oxygen electrode materials that show superior activity and stability for oxygen reduction and evolution...

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A new class of layered swedenborgite structured Y0.8Er0.2BaCo3.2Ga0.8O7+δ is proposed for oxygen electrode reactions in reversible ceramic cells because of its low thermal expansion and high chemical bulk diffusion coefficients.

A reliable and high performance proton-conducting reversible solid oxide cell (P-RSOCs) is developed to generate electricity in a protonic ceramic fuel cell (PCFC) mode and to generate hydrogen gas in a protonic ceramic electrolysis (PCEC) mode in a single electrochemical device. Herein we propose a modified triple conducting (H + /O 2− /e − ) steam (air) electrode through the infiltration of an Sm 0.2 Ce 0.8 O 2-δ (SDC) oxygen-ionic conductor, because the polarization resistance (R p ) of P-RSOCs mainly comes from the steam (air) electrode in both the operational modes. The SDC-infiltrated nanoparticles on the composite BaCo 0.4 Zr 0.1 Fe 0.4 Y 0.1 O 3+δ (BCZFY)-BaCe 0.7 Zr 0.1 Y 0.2-x Yb x O 3-δ (BCZYYb) electrode result in a considerable improvement in the oxygen reduction reaction and oxygen evolution reaction catalytic activity at 600-700°C due to the extension of electrochemical active sites with the increasing of surface area. In addition, the enhanced ionic conduction of a triple conducting composite using infiltrated oxygen-ionic SDC conductors leads to an effective decrease in the R p (1.388→1.079 Ω•cm 2 at 600°C symmetric cell) with improved cell performance in both the PCFC and PCEC modes. Furthermore, the NiO-BCZYYb anode-supported cell with the SDC-infiltrated composite BCZFY-BCZYYb air electrode shows excellent durability in the PCFC and PCEC modes without any degradation during 250 h each at 650°C.