一些 EPR 方法在研究羟基自由基与 PEFC 相关氟化有机酸反应产生的自由基物种中的应用,Physical Chemistry Chemical Physics

当前位置： X-MOL 学术 › Phys. Chem. Chem. Phys. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

一些 EPR 方法在研究羟基自由基与 PEFC 相关氟化有机酸反应产生的自由基物种中的应用
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2022-09-07 , DOI: 10.1039/d2cp02370a
Takashi Kukisawa ₁ , Yutaka Kuwabara ₁ , Atsuko Y Nosaka ₁ , Yoshio Nosaka ₁

Affiliation

˙OH 自由基与全氟烷基磺酸和羧酸反应的基本信息对于理解聚合物电解质燃料电池 (PEFC) 的降解非常重要。在本研究中，通过电子顺磁共振（EPR）光谱的三种方法检测和分析这些反应产生的中间自由基。传统的 CW-EPR 技术应用于冷冻和流动的水溶液系统以检测反应中间体，而时间分辨 (TR) EPR 技术应用于流动的溶液系统以分析自旋动力学参数。测试的反应物是CF ₃ SO ₃ H、CHF ₂ CF ₂ SO ₃ H、CH₃ SO₃ H、CF₃ COOH、CHF₂ COOH等，在紫外激光的照射下，_{H 2} O₂生成˙OH自由基检测到的自由基有˙SO₃^-、˙CO₂^-、˙CF₃、˙CF₂ CF₂ SO₃ H、˙CF₂ COOH等。基于TR-EPR光谱的测量，信号强度的依赖性对时间和磁场进行分析，然后分析纵向弛豫时间（ T ₁) 并对这些自由基物种的寿命进行了评估。比较了检测中间自由基的三种 EPR 方法，以显示这些技术的局限性。基于检测到的自由基，讨论了报道的全氟酸降解机制。

"点击查看英文标题和摘要"

Applications of some EPR methods to the investigation of the radical species produced by the reactions of hydroxyl radicals with PEFC-related fluorinated organic acids

Fundamental information on the reactions of ˙OH radicals with perfluoroalkyl sulfonic acids and carboxylic acids is important for understanding the degradation of polymer electrolyte fuel cells (PEFCs). In the present research, the intermediate radicals produced by these reactions were detected and analyzed by means of three methods of electron paramagnetic resonance (EPR) spectroscopy. The conventional CW-EPR technique was applied to both frozen and flowing aqueous solution systems for detecting the reaction intermediates, while the time-resolved (TR) EPR technique was applied to the flowing solution system for analyzing spin dynamics parameters. The reactants tested were CF₃SO₃H, CHF₂CF₂SO₃H, CH₃SO₃H, CF₃COOH, CHF₂COOH, etc., and the ˙OH radical was generated from H₂O₂ by the irradiation of a UV laser. The radicals detected were ˙SO₃⁻, ˙CO₂⁻, ˙CF₃, ˙CF₂CF₂SO₃H, ˙CF₂COOH, etc. Based on the measurements of TR-EPR spectra, the dependences of the signal intensity on the time and magnetic field were analyzed, and then the longitudinal relaxation time (T₁) and the lifetime of these radical species were evaluated. The three EPR methods for detecting the intermediate radicals were compared to show the limitations of these techniques. Based on the detected radicals, the degradation mechanism reported for perfluoro acids was discussed.

更新日期：2022-09-07

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南