Fluorescence detection of hydroxyl radical generated from oxygen reduction on Fe/N/C catalyst

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 H 2 O 2 generated from the ORR was observed, which suggests that •OH is not generated from the decomposition of H 2 O 2 as traditional viewpoint.