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 center dot OH radical, severely hampers its applications. However, the exact mechanism for generation of center dot OH is unclear yet. Herein, we developed a fluorescent method to effectively detect center dot OH generated from ORR on Fe/N/C catalyst by using coumarin as a fluorescent probe. A great difference in potential dependence between center dot OH and H2O2 generated from the ORR was observed, which suggests that center dot OH is not generated from the decomposition of H2O2 as traditional viewpoint.