2022
DOI: 10.1002/cssc.202201571
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On the Radical‐Induced Degradation of Quaternary Ammonium Cations for Anion‐Exchange Membrane Fuel Cells and Electrolyzers

Abstract: Four benzylic‐type quaternary ammonium (QA) compounds with different electron density at the phenyl group were evaluated for their susceptibility against degradation by radicals. Time‐resolved absorption spectroscopy indicated that radicals with oxidizing and reducing character were formed upon oxidation by HO⋅ and O⋅− (conjugate base of HO⋅). It was estimated that, dependent on the QA, 18–41 % of the formed radicals were oxidizing with standard electrode potentials (E0) above 0.276 V and 13–23 % exceeded 0.68… Show more

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Cited by 12 publications
(10 citation statements)
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“…While the mechanisms of AEM degradation by OH – are well-established, radical-induced degradation remains largely unknown. They are, however, suspected of playing a crucial role in the degradation of cationic moieties of the AEMs. , …”
Section: Resultsmentioning
confidence: 99%
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“…While the mechanisms of AEM degradation by OH – are well-established, radical-induced degradation remains largely unknown. They are, however, suspected of playing a crucial role in the degradation of cationic moieties of the AEMs. , …”
Section: Resultsmentioning
confidence: 99%
“…18 These experiments (see SI, section Experimental Methods viii, p 10) evidenced that DMPO diffused across the FAA-3-20-rf AEM in 25 min as shown in Table S4, so we limited our observations to 15 min, regardless of the observed slow diffusion of DMPO. In this study, we investigated only the cathode side since oxygen radicals are most expected to attack the membrane 26,27 and carbon support, leading to their deterioration. 28 The experimental (black solid line) and simulated (green dashed line) EPR spectra recorded just after starting the AEMFC EPR operation and DMPO applied on cathode sides are given in Figure 1 for all of the investigated cathode catalysts.…”
Section: ■ Results and Discussionmentioning
confidence: 99%
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“…At the anode the ionomer is held at a strongly oxidizing potential and exposed to possible oxidizing species/intermediates produced during the oxygen-evolution reaction (OER). The oxidative and radical stability of anion exchange polymers has been investigated to various extents, [40][41][42][43][44] but few studies are conducted under device-relevant operating configurations and conditions.…”
Section: Introductionmentioning
confidence: 99%
“…It has been proved that the AEMs would be attacked by free radicals such as •OH, •OOH, and other oxidizers formed in the presence of oxygen during AEMFC operation. 42 The Fenton test is a commonly used method for simulating the generation of •OH and •OOH free radicals to assess the oxidative stability of the polymer electrolyte membrane. Figure 7a displays the weight loss of the prepared membranes after the Fenton test at 60 °C.…”
Section: ■ Introductionmentioning
confidence: 99%