Summary This study reports the enhanced performance of protonic ceramic fuel cells by adopting electrode‐electrolyte cathode functional layers (CFLs). PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) and BaZrxCe0.8−xY0.1Yb0.1O3−δ (BZCYYb) were used as cathode and electrolyte materials, respectively. Thin‐film CFLs comprising PBSCF and BZCYYb composites were inserted between the electrode and the electrolyte. Power output in the cells with CFLs was enhanced by approximately 4% to 20% at a temperature range of 450°C to 550°C, compared to those without CFLs. Impedance analysis confirmed that the polarization electrode resistance significantly reduced with the adoption of CFLs. The extended interface between the cathode and electrolyte in the CFLs was considered to have contributed to the reduced electrode impedance. The distribution of relaxation times analyzed by fitting the impedance data revealed the charge transfer and proton incorporation steps along with the PBSCF/BZCYYb interface in CFLs as the main contribution to the electrode performance enhancement in cathodic polarization reactions.

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This study reports the performance and durability of a protonic ceramic fuel cells (PCFCs) in an ammonia fuel injection environment. The low ammonia decomposition rate in PCFCs with lower operating temperatures is improved relative to that of solid oxide fuel cells by treatment with a catalyst. By treating the anode of the PCFCs with a palladium (Pd) catalyst at 500 °C under ammonia fuel injection, the performance (peak power density of 340 mW cm−2 at 500 °C) is approximately two‐fold higher than that of the bare sample not treated with Pd. Pd catalysts are deposited through an atomic layer deposition post‐treatment process on the anode surface, in which nickel oxide (NiO) and BaZr0.2Ce0.6Y0.1Yb0.1O3–δ (BZCYYb) are mixed, and Pd can penetrate the anode surface and porous interior. Impedance analysis confirmed that Pd increased the current collection and significantly reduced the polarization resistance, particularly in the low‐temperature region (≈500 °C), thereby improving the performance. Furthermore, stability tests showed that superior durability is achieved compared with that of the bare sample. Based on these results, the method presented herein is expected to represent a promising solution for securing high‐performance and stable PCFCs based on ammonia injection.

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In this study, the performance and durability of a Pt/Cu bimetallic catalyst membrane electrode assembly (MEA) for use in polymer electrolyte membrane fuel cells (PEMFCs)-fabricated via plasma-enhanced atomic layer deposition and sputtering-were investigated. The high production costs of Pt-based catalysts limit the commercialization of PEMFCs. Therefore, research to dramatically reduce the loadings of noble metal catalysts, such as Pt, has steadily progressed. Atomic layer deposition may considerably reduce the amount of supported catalyst by precisely controlling the composition and thickness of the catalyst via a self-limiting reaction. According to D-band theory, the Cu catalyst of the Pt/Cu MEA weakened the bonds between the Pt catalyst and oxygen species and improved the oxygen reduction reaction compared to those of the existing Pt MEA. The performance and electrochemical surface area (ECSA) of the Pt/Cu MEA were determined using I-V measurements and cyclic voltammetry, and the durability of the Pt/Cu MEA was analyzed using electrochemical impedance spectroscopy and the accelerated stress test. Thus, when the Pt/Cu MEA was used, the performance and ECSA were improved, and the impedance decreased, compared to those of the Pt MEA.