Self-assembled CoFeNi alloy-based perovskite oxide as the catalyst layer for stable direct ammonia protonic ceramic fuel cells

Ammonia is a promising fuel for protonic ceramic fuel cells (PCFCs) as it has a higher energy density and storage capacity than hydrogen. However, due to low catalytic activity and poor stability, the conventional Ni and proton conductor cermet anode struggles to operate efficiently in ammonia atmospheres at intermediate temperatures such as 550 °C. In this study, we present a self-assembled BaCo 0.43 Fe 0.43 Ni 0.17 O 3-δ /BaCe 0.8 Y 0.2 O 3-δ (BMO7/BCY3) as an anode catalytic layer (ACL), in situ phase separation and reduction of BaO/CoFeNi from BMO phase and nano alloy grown on the proton conductor phase (BCY) host oxide under reduced atmosphere. The co-reduction of the Co, Fe, and Ni promotes Fe reduction, and the resulting alloy aids in ammonia adsorption and nitrogen desorption, leading to high ammonia decomposition rates at reduced temperatures (550 °C). Consequently, PCFC with the BMO7/BCY3 ACL demonstrates enhanced power output with a 74 % improvement and more importantly a significantly improved cell lifetime with 60 h operation without obvious power degradation compared to the gradual deterioration of the cell without an ACL that completely failed at 43h when using ammonia fuel at 550 °C. • A self-assembled perovskite composite catalytic layer used for ammonia conversion. • In situ formation of the CoFeNi nanoalloy for efficient ammonia decomposition. • The CoFeNi alloy enhances the ammonia adsorption and nitrogen desorption ability. • PCFC with ACL improves the performance and stability in ammonia at 550 °C. • The ACL protects the Ni in the anode of PCFC from being agglomerated and coarsening.