Detection of Reactive Oxygen Species in Anion Exchange Membrane Fuel Cells using In Situ Fluorescence Spectroscopy

The objectives of this study were: 1) to confirm superoxide anion radical (O₂^.- ) formation, and 2) to monitor in real time the rate of O₂^.- generation in an operating anion exchange membrane (AEM) fuel cell using in situ fluorescence spectroscopy. 1,3-Diphenlisobenzofuran (DPBF) was used as the fluorescent molecular probe owing to its selectivity and sensitivity toward O₂^.- in alkaline media. The activation energy for the in situ generation of O₂^.- during AEM fuel cell operation was estimated to be 18.3 kJ mol^-1 . The rate of in situ generation of O₂^.- correlated well with the experimentally measured loss in AEM ion-exchange capacity and ionic conductivity attributable to oxidative degradation.