Self-Construction of Efficient Interfaces Ensures High-Performance Direct Ammonia Protonic Ceramic Fuel Cells

Direct ammonia protonic ceramic fuel cells (PCFCs) are highly efficient energy conversion devices since ammonia as a carbon-neutral hydrogen-rich carrier shows great potential for storage and long-distance transportation when compared with hydrogen fuel. However, traditional Ni-based anodes readily suffer from severe structural destruction and dramatic deactivation after long-time exposure to ammonia. Here a Sr₂ Fe_1.35 Mo_0.45 Cu_0.2 O_6-δ (SFMC) anode catalytic layer (ACL) painted onto a Ni-BaZr_0.1 Ce_0.7 Y_0.1 Yb_0.1 O_{3- δ} (BZCYYb) anode with enhanced catalytic activity and durability toward the direct utilization of ammonia is reported. A tubular Ni-BZCYYb anode-supported cells with the SFMC ACL show excellent peak power densities of 1.77 W cm^-2 in wet H₂ (3% H₂ O) and 1.02 W cm^-2 in NH₃ at 650 °C. A relatively stable operation of the cells is obtained at 650 °C for 200 h in ammonia fuel. Such achieved improvements in the activity and durability are attributed to the self-constructed interfaces with the phases of NiCu or/and NiFe for efficient NH₃ decomposition, resulting in a strong NH₃ adsorption strength of the SFMC, as confirmed by NH₃ thermal conversion and NH₃ -temperature programmed desorption. This research offers a valuable strategy of applying an internal catalytic layer for highly active and durable ammonia PCFCs.