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

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 PrNi_0.7Co_0.3O_3-δ (PNC) backbone infused with oxygen vacancy-rich praseodymium oxide (PrO_x) nanoparticles. This design leverages the interplay between surface and bulk properties to enhance oxygen adsorption, diffusion, and catalytic kinetics. The PrO_x 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.