Symmetric solid oxide fuel cells (SSOFCs) have gained significant attention owing to their cost-effective fabrication, superior thermomechanical compatibility, and enhanced long-term stability. Ammonia (NH₃), an excellent hydrogen carrier, is a promising clean energy source with high energy density, easy transportation and storage. Notably, NH₃ contained only nitrogen and hydrogen, making it carbon-free. In this study, we synthesize the highly active symmetric electrode material Pr_0.32Sr_0.48Fe_0.75Ni_0.2Ru_0.05O_3−δ (PSFNRu) by replacing partial Fe in Pr_0.32Sr_0.48Fe_0.8Ni_0.2O_3−δ (PSFN) with 5 mol% Ru. PSFNRu possesses a sufficient quantity of oxygen vacancies, with the capacity to in-situ exsolved alloy nanoparticles (ANPs) in a reducing atmosphere. This nanocomposite is found to promote electrochemical reactions. For example, at 800 °C, the SSOFC employing the PSFNRu electrode achieves a peak power density (PPD) of 736 mW·cm⁻² when using hydrogen (H₂) as the fuel. Under NH₃ conditions, the cell delivers a PPD of 547 mW·cm⁻², significantly surpassing the 462 mW·cm⁻² recorded for a comparable cell employing the PSFN electrode. The enhanced cell performance is mainly ascribed to Ru doping, which boosts the ORR activity and facilitates the in-situ exsolution of ANPs at the anode, increasing active sites and accelerating NH₃ decomposition. In addition, remarkable operational stability of the single cell (172 h under NH₃ fuel at 700 °C) is also demonstrated. These encouraging experimental results highlight the superiority of PSFNRu as the bi-functional electrodes for direct ammonia symmetric solid oxide fuel cells (DA-SSOFCs), and providing a potential and reliable pathway towards accelerating the development of DA-SSOFCs.

To enhance the performance and widespread use of solid oxide fuel cells (SOFCs), addressing the low-temperature (< 650 °C) electrochemical performance and operational stability issues of cathode materials is crucial. Here, we propose an innovative approach to enhance oxygen ion mobility and electrochemical performance of perovskite oxide by substituting some oxygen sites with chlorine anions. The designed SrTa_0.1Fe_0.9O_3−δ−xCl_x (x = 0.05 and 0.10) exhibits improved performance compared to SrTa_0.1Fe_0.9O_3−δ (STF). SrTa_0.1Fe_0.9O_2.95−δCl_0.05 (STFCl0.05) shows the lowest area-specific resistance (ASR) value on Sm_0.2Ce_0.8O_1.9 (SDC) electrolyte. At 600 °C, STFCl0.05 achieves an ASR value of 0.084 Ω·cm², and a single cell with STFCl0.05 reaches a higher peak power density (PPD) value (1143 mW·cm⁻²) than that with STF (672 mW·cm⁻²). Additionally, besides exhibiting excellent oxygen reduction reaction (ORR) activity at lower temperatures, the STFCl0.05 cathode demonstrates good CO₂ tolerance and operational stability. Symmetrical cell operation lasts for 150 h, and single cell operation endures for 720 h without significant performance decline. The chlorine doping approach effectively enhances ORR activity and stability, making STFCl0.05 a promising cathode material for low-temperature SOFCs.