Catalyst Functionalization for Elevating Performance in Ammonia Protonic Ceramic Fuel Cells via Relay...

Direct ammonia proton ceramic fuel cell is one of the most attractive strategies for ammonia to power at intermediate temperatures (400°C-600°C). Yet, it still remains greatly challenging, involving complex and sluggish processes, such as ammonia oxidation, ammonia decomposition (ADR), and hydrogen oxidation reaction (HOR), which always proceeds with high overpotential and low current density. Herein, we adopt the relay thermo-electrocatalysis strategy via catalyst functionalization for enhancing the performance of NH₃-PCFCs, where ammonia undergoes ADR at the catalytic layer and then enters the anode to undergo HOR. The strategy not only promotes the performance of NH₃-PCFCs (in the case of H₂ and NH₃) but also enhances the absolute performance in the same fuel gas compared with bare cells. The Ru/CZ4 was synthesized for catalyst functionalization for enhanced NH₃-PCFCs and a general principle for designing well-matched catalysts was proposed. Indeed, the peak power density (PPD) of Ru/CZ4 cell achieves 615 and 576 mW cm^{- 2} for using H₂ and NH₃, respectively, which are 1.8- and 2.0-fold higher than bare cells (327 and 283 mW cm^{- 2} for using H₂ and NH₃). Additionally, the ammonia-to-hydrogen PPD ratio reaches to 93.7%, revealing the superior performance in both H₂ and NH₃ fuels. Furthermore, the detailed experiments and discussion were conducted to gain insight into the incorporated anode for the superior performance of NH₃-PCFC. This research offers valuable insights into the structural design and performance optimization of solid oxide fuel cells using hydrogen-rich fuels.