Boosting Ammonia-Fueled Protonic Ceramic Fuel Cells with RuFe Nanoparticle Exsolution: Enhanced Performance via Secondary Redox Treatment

Ammonia, with high hydrogen content and carbon neutrality, is an ideal fuel for protonic ceramic fuel cells (PCFCs). However, the limited electrochemical efficiency and durability of ammonia-based PCFCs have posed challenges for broader implementation. Herein, a novel anode material, Ni-Ba(Zr_0.1Ce_0.7Y_0.1Yb_0.1)_0.94Ru_0.03Fe_0.03O_3-δ (BZCYYbRF), developed by co-doping with Ru and Fe is introduced, which promotes the exsolution of RuFe nanoparticles under reducing conditions. A secondary redox process further enhances nanoparticle redistribution, increasing catalytic activity and improving ammonia decomposition and hydrogen oxidation, as well as the charge transfer at the heterointerface, leading to a marked improvement in the electrochemical performance of the PCFC under both hydrogen and ammonia fuel conditions. A single cell utilizing BZCYYbRF as the anode achieves a peak power density of 700 mW cm⁻² at 650 °C under NH₃ fuel, with stable operation for up to 150 h. Additionally, secondary redox treatment improved performance to 807 mW cm⁻² at 650 °C. The innovation lies in the co-doping and redox-driven nanoparticle exsolution strategy, significantly boosting PCFC performance and stability, positioning this anode as a breakthrough for direct ammonia fuel cells.