Pyrolyzed Fe/N/C catalyst has been considered as the most promising candidate to replace Pt for oxygen reduction reaction (ORR) in fuel cells. However, poor stability of Fe/N/C catalyst, mainly attributed to the oxidation corrosion by aggressive •OH radical, severely hampers its applications. However, the exact mechanism for generation of •OH is unclear yet. Herein, we developed a fluorescent method to effectively detect •OH generated from ORR on Fe/N/C catalyst by using coumarin as a fluorescent probe. A great difference in potential dependence between •OH and H₂O₂ generated from the ORR was observed, which suggests that •OH is not generated from the decomposition of H₂O₂ as traditional viewpoint.

中文翻译：

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Fe / N / C催化剂上氧还原产生的羟基自由基的荧光检测

热解Fe / N / C催化剂被认为是替代Pt替代燃料电池中氧还原反应（ORR）的最有希望的候选者。然而，Fe / N / C催化剂稳定性差，主要归因于侵蚀性•OH自由基的氧化腐蚀，严重阻碍了其应用。但是，产生•OH的确切机制尚不清楚。本文中，我们开发了一种荧光方法，以香豆素为荧光探针，可有效检测Fe / N / C催化剂上ORR产生的•OH。观察到ORH产生的•OH和H ₂ O ₂之间的电位依赖性存在很大差异，这表明从传统观点来看，•OH不是由H ₂ O ₂的分解产生的。