Hybridizing Electrode Interface Structures in Protonic Ceramic Cells for Durable, Reversible Hydrogen and Power Generation

Abstract Protonic ceramic electrochemical cells (PCECs) represent a transformative technology for sustainable hydrogen production and power generation by converting energy between chemical and electrical forms. Operating at intermediate temperatures, PCECs utilize proton‐conducting electrolytes, achieving high efficiency and reduced degradation. However, a major bottleneck lies at the oxygen electrode due to sluggish kinetics and limited active sites. To address this, we present a hybrid oxygen electrode featuring PrNi0.7Co0.3O3–δ (PNC) backbone infused with oxygen vacancy‐rich praseodymium oxide (PrOx) nanoparticles. This design leverages the interplay between surface and bulk properties to enhance oxygen adsorption, diffusion, and catalytic kinetics. The PrOx introduces abundant oxygen vacancies and modulates the d‐band center for optimal adsorption energy, while the PNC backbone provides robust proton conduction and stabilizes reaction intermediates. Cells incorporating this hybrid electrode demonstrate a peak power density of 1.56 W cm−2 at 600 °C in fuel cell mode and a current density of 2.25 A cm−2 at 1.30 V in electrolysis mode. Faradaic and energy efficiency reach 96.8% and 89.9%, respectively, with exceptional thermal cycling stability and reduced polarization resistance (0.079 Ω cm2). This study underscores the potential of advanced electrode architectures to enhance the efficiency, durability, and applicability of PCECs in renewable energy systems.