Over the last few decades, because of the significant development of anion exchange membranes, increasing efforts have been devoted the realization of anion exchange membrane fuel cells (AEMFCs) that operate with the supply of hydrogen generated on-site. In this paper, ammonia was selected as a hydrogen source, following which the effect of conceivable impurities, unreacted NH₃ and atmospheric CO₂, on the performance of AEMFCs was established. As expected, we show that these impurities worsen the performance of AEMFCs significantly. Furthermore, with the help of in situ attenuated total reflection infrared (ATR-IR) spectroscopy, it was revealed that the degradation of the cell performance was primarily due to the inhibition of the hydrogen oxidation reaction (HOR). This is attributed to the active site occupation by CO-related adspecies derived from (bi)carbonate adspecies. Interestingly, this degradation in the HOR activity is suppressed in the presence of both NH₃ and HCO₃^- because of the bicarbonate ion consumption reaction induced by the existence of NH₃. Further analysis using in situ ATR-IR and electrochemical methods revealed that the poisonous CO-related adspecies were completely removed under NH₃-HCO₃^- conditions, accompanied by the improvement in HOR activity. Finally, a fuel cell test was conducted by using the practical AEMFC with the supply of NH₃-contained H₂ gas to the anode and ambient air to the cathode. The result confirmed the validity of this positive effect of NH₃-HCO₃^- coexistence on CO₂-tolerence of AEMFCs. The cell performance achieved nearly 95% of that without any impurity in the fuels. These results clearly show the impact of the chemically induced bicarbonate ion consumption reaction on the realization of highly CO₂-tolerent AEMFCs.

	Year	Citations

About