Revealing the role of ionic liquids in promoting fuel cell catalysts reactivity and durability

Arezoo Avid; Jesus López Ochoa; Ying Huang; Yuanchao Liu; Plamen Atanassov; Iryna V Zenyuk

doi:10.1038/s41467-022-33895-5

Revealing the role of ionic liquids in promoting fuel cell catalysts reactivity and durability

Nat Commun. 2022 Oct 26;13(1):6349. doi: 10.1038/s41467-022-33895-5.

Authors

Arezoo Avid^{1

2}, Jesus López Ochoa^{1

2}, Ying Huang^{2

3}, Yuanchao Liu^{1

2}, Plamen Atanassov^{1

2}, Iryna V Zenyuk^{4

5

6}

Affiliations

¹ Department of Chemical and Biomolecular Engineering, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA.
² National Fuel Cell Research Center, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA.
³ Department of Materials Science and Engineering, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA.
⁴ Department of Chemical and Biomolecular Engineering, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA. iryna.zenyuk@uci.edu.
⁵ National Fuel Cell Research Center, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA. iryna.zenyuk@uci.edu.
⁶ Department of Materials Science and Engineering, University of California Irvine, 221 Engineering Service Rd., Irvine, CA, 92617, USA. iryna.zenyuk@uci.edu.

Abstract

Ionic liquids (ILs) have shown to be promising additives to the catalyst layer to enhance oxygen reduction reaction in polymer electrolyte fuel cells. However, fundamental understanding of their role in complex catalyst layers in practically relevant membrane electrode assembly environment is needed for rational design of highly durable and active platinum-based catalysts. Here we explore three imidazolium-derived ionic liquids, selected for their high proton conductivity and oxygen solubility, and incorporate them into high surface area carbon black support. Further, we establish a correlation between the physical properties and electrochemical performance of the ionic liquid-modified catalysts by providing direct evidence of ionic liquids role in altering hydrophilic/hydrophobic interactions within the catalyst layer interface. The resulting catalyst with optimized interface design achieved a high mass activity of 347 A g^-1_Pt at 0.9 V under H₂/O₂, power density of 0.909 W cm^-2 under H₂/air and 1.5 bar, and had only 0.11 V potential decrease at 0.8 A cm^-2 after 30 k accelerated stress test cycles. This performance stems from substantial enhancement in Pt utilization, which is buried inside the mesopores and is now accessible due to ILs addition.

Grants and funding

1652445/National Science Foundation (NSF)