Surface reconstruction of a perovskite air electrode boosts the activity and durability of reversible protonic ceramic electrochemical cells

Reversible protonic ceramic electrochemical cells (R-PCECs) display a vast range of potential applications as an efficient and low-cost technology for the generation of electricity and the production of high-value-added chemicals. However, electrode surface reaction kinetics, especially the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), pose significant challenges to the development of R-PCECs. To achieve the commercialization of R-PCECs, the key lies in the development of an air electrode that possesses both high activity and durability. In this study, a perovskite oxide electrode composed of Pr0.5Sr0.5Co0.9Nb0.1O3-δ (PSCN) is designed as a novel air electrode for R-PCECs. During operation, nanoparticles (NPs) with a formula SrCo0.5Nb0.5O3-δ (SCN) are in situ generated on the PSCN framework, thus forming an SCN-coated PSCN (SCN–PSCN) composite with abundant interfaces. These NPs and interfaces notably boost the activity of the composite electrode. As the air electrode for R-PCECs, the SCN–PSCN electrode exhibits excellent performance at 600 °C, in dual modes of fuel cell and electrolysis cell. It achieves a peak power density of 0.89 W cm−2 and a current density of 1.27 A cm−2 at 1.3V. Also, the SCN–PSCN air electrode demonstrates stability exceeding 100 h in both FC and EC modes. •A novel air electrode decorated with self-generated nanoparticles is designed.•A peak power density of 1.78 W cm−2 is acquired from a single cell at 700 °C.•A remarkable current density of −3.75 A cm−2 was achieved at 1.3V and 700 °C.•The cells show good durability in both fuel cell and electrolysis cell mode.