Enhancing Low-Temperature Direct Ammonia Fuel Cell Performance with PtIr/C Catalysts in a Membrane-Electrode Assembly

Abstract

Direct ammonia fuel cells (DAFCs) are promising energy-conversion devices owing to their high energy densities and ease of storage; however, their application is hindered by the sluggish kinetics of the ammonia oxidation reaction (AOR) and catalyst poisoning. In this study, we systematically investigate the performance of Pt-based catalysts (Pt/C, PtRu/C, and PtIr/C) in the AOR using both half- and single-cell configurations. PtIr/VC with a Pt: Ir ratio different from that of commercial PtIr/C (c-PtIr/C) is synthesized to optimize the Ir utilization. To bridge the gap between half-cell and single-cell configurations, the operating conditions of the membrane-electrode assembly-based single-cell DAFC are optimized, including the anion-exchange membrane, temperature, and conditioning process. Higher temperatures and piperidinium functional groups enhance the DAFC performance. These findings provide insights that will facilitate the rational design of DAFC catalysts and operating conditions for improved performance and durability.