Mechanistic Studies of Improving Pt Catalyst Stability at High Potential via Designing Hydrophobic Micro-Environment with Ionic Liquid in PEMFC

Recently, the focus of fuel cell technologies has shifted from light-duty automotive to heavy-duty vehicle applications, which require improving the stability of membrane electrode assemblies (MEAs) at high constant potential. The hydrophilicity of Pt makes it easy to combine with water molecules and then oxidize at high potential, resulting in poor durability of the catalyst. In this work, an ionic liquid [BMIM][NTF2] was used to modify the Pt catalyst (Pt/C + IL) to create a hydrophobic, antioxidant micro-environment in the catalyst layer (CL). The effect of [BMIM][NTF2] on the decay of the CL performance at high constant potential (0.85 V) for a long time was investigated. It was found that the performance attenuation of Pt/C + IL in the high-potential range (OCV 0.75 V) was less than that of commercial Pt/C after 10 h. The Pt-oxide coverage test showed that the hydrophobic micro-environment of the CL enhanced the stability by inhibiting Pt oxidation. In addition, the electrochemical recovery of Pt oxides showed that the content of recoverable oxides in Pt/C + IL was higher than that in commercial Pt/C. Overall, modifying the Pt catalyst with hydrophobic ionic liquid is an effective strategy to improve the catalyst stability and reduce the irreversible voltage loss caused by the oxide at high constant potential.

Automated summary

Recently, there has been a shift in focus in fuel cell technologies from light-duty automotive to heavy-duty vehicle applications, necessitating improved stability of membrane electrode assemblies (MEAs) at high constant potential. This study investigates the use of the ionic liquid [BMIM][NTF2] to modify Pt catalysts and create a hydrophobic, antioxidant micro-environment in the catalyst layer (CL). The results show that the modified Pt catalyst exhibits enhanced stability and reduced irreversible voltage loss caused by oxide formation at high constant potential.