Protonic ceramic electrochemical cells (PCECs) show promise for efficient hydrogen production and power generation, yet surface degradation of perovskite air electrodes caused by A-site cation segregation poses a challenge. Rather than suppressing surface segregation, this work leverages the opportunity, unlocking the latent potential of the catalytically active, B-site-enriched subsurface beneath the segregated surface layers. Using PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) as a model electrode, we expose a subsurface enriched with oxygen vacancies through an alkaline treatment. As a result, the electrolysis current density increases by 28% at 1.3 V and the peak power density improves by 24% at 650 °C in reversible PCEC operation, while maintaining stability. These improvements arise from enhanced H2O/O2 adsorption and dissociation, and facilitated charge transfer, supported by experimental and theoretical analysis. This surface activation strategy is further validated across multiple perovskite air electrodes, demonstrating a general approach to revive segregated electrodes by harnessing the self-reconstructed subsurface.
Lin et al. (Tue,) studied this question.