Issue 18, 2023

Fluoroalkyl phosphonic acid radical scavengers for proton exchange membrane fuel cells

Abstract

Radical-induced degradation of proton exchange membranes limits the durability of proton-exchange membrane fuel cells. Cerium is widely used as a radical scavenger, but the migration of cerium ions to the catalyst layer has been an unresolved issue, reducing its effectiveness over time. Here, we report phosphonic acids as a promising class of radical scavengers, showing competent radical scavenging activity compared to cerium without the migration issue. The ex situ Fenton test shows that the fluoride emission rate for Nafion membrane incorporated with fluoroalkyl phosphonic acid ranged from 0.22 to 0.37 μg F cm−2 h−1, lower than that of the cerium-incorporated Nafion™ membrane (0.39 μg F cm−2 h−1). The in situ open circuit voltage hold test confirmed that a phosphonic acid-incorporated Nafion™ membrane has a 58% lower fluoride emission rate compared to the baseline. Density functional theory calculations indicate that the activation energy of the hydroxyl radical scavenging reaction of an alkyl phosphonic acid is only 0.68 eV, suggesting an effective radical scavenging pathway.

Graphical abstract: Fluoroalkyl phosphonic acid radical scavengers for proton exchange membrane fuel cells

Supplementary files

Article information

Article type
Communication
Submitted
05 Dec. 2022
Accepted
06 Apr. 2023
First published
06 Apr. 2023
This article is Open Access
Creative Commons BY-NC license

J. Mater. Chem. A, 2023,11, 9748-9754

Fluoroalkyl phosphonic acid radical scavengers for proton exchange membrane fuel cells

T. Agarwal, S. Adhikari, Y. S. Kim, S. Komini Babu, D. Tian, C. Bae, N. N. T. Pham, S. G. Lee, A. K. Prasad, S. G. Advani, A. Sievert, W. P. Rasika Liyanage, T. E. Hopkins, A. Park and R. Borup, J. Mater. Chem. A, 2023, 11, 9748 DOI: 10.1039/D2TA09421E

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