Performance-enhanced direct ammonia protonic ceramic fuel cells using CeO2-supported Ni and Ru catalyst layer

Abstract

Ammonia is an exceptional fuel for solid oxide fuel cells (SOFCs), because of the high content of hydrogen and the advantages of carbon neutrality. However, the challenge lies in its unsatisfactory performance at intermediate temperatures (500–600 °C), impeding its advancement. An electrolyte-supported proton-ceramic fuel cell (PCFC) was fabricated employing BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY) as the electrolyte and Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) as the cathode. In this study, the performance of PCFC using NH₃ as fuel within an operating temperature range of 500–700 °C was improved by adding an M(Ni,Ru)/CeO₂ catalyst layer to reconstruct the anode surface. The electrochemical performance of direct ammonia PCFC (DA-PCFC) were improved to different extents. Compared to H₂ as fuel, the degradation ratio of peak power densities (PPDs) of Ni/CeO₂-loaded PCFC fueled with NH₃ decreased at 700–500 °C, with a decrease to 13.3% at 700 °C and 30.7% at 500 °C. The findings indicate that Ru-based catalysts have a greater promise for direct ammonia SOFCs (DA-SOFCs) at operating temperatures below 600 °C. However, the enhancement effect becomes less significant above 600 °C when compared to Ni-based catalysts.