Synergistic poisoning effect of NH3 and NOx gases in the cathode air on proton exchange membrane fuel cell

Abstract

Nitrogen oxides (NOx) and ammonia (NH3) are coexisting in fuel cell vehicles’ working condition such as urban industrial areas, which are harmful impurities to proton exchange membrane fuel cell (PEMFC). In this work, an experimental investigation between NH3 alone, NOx alone, and 1:1 mixed NH3/NOx are conducted at different concentrations. Voltage time curve and electrochemical impedance spectroscopy (EIS) analyses show that mixed gases cause slighter poison effect than single gas. Mixed 20 ppm NOx and 20 ppm NH3 caused a −14 mV/h voltage decay rate, while that of 20 ppm NOx alone and 20 ppm NH3 alone were −5 mV/h and −18 mV/h. Meanwhile, by comparing the poison and recovery processes between different impurity gases at different concentrations, mechanism of synergistic poisoning is proposed. A fast voltage decay rate caused by NOx and an irreversible performance loss caused by NH3 are observed in sequence at higher concentration, which due to the different adsorption energy of NOx and NH3 and the different reactions occurring in the membrane electrode assemblies (MEAs).