Effects of NOx and SO2 in cathode stream on the performance of PEMFC

Anegative effect of NOx,mainly NO2,onthe performance ofproton exchange membrane fuel cell(PEMFC)1-3]was reported·The negative effects of NO2with concentrations ranging from4×10-5%(in volume,the same as follow)to 5×10-4%were re-ported to be reversible …

Effects of NOx and SO2 in cathode stream on the performance of PEMFC

The effects of NOx(in a ratio of NO:NO2 = 9:1) and SO2 in cathode stream on the performance of a single proton exchange membrane fuel cell (PEMFC) were investigated. NOx with concentrations of 1×10-3% (in volume, the same as follows), 1.4×10-2% and 1×10-3% could cause significant detrimental effects on the cell performance. However, nearly complete recovery of the cell performance could be observed after NOx was shut off and purged with clean air. The electrochemical measurements suggested that the impacts of NOx resulted mainly from the superposition of the oxygen reduction reaction (ORR),NO and HNO2 oxidation reactions, and the increased cathodic impedance. Trace SO2 with concentrations of 5 × 10-6%, 5 ×10-3%, 2 × 10-4% and 3.2 × 10-4% influenced the cell much severer, which could be attributed to its strong adsorption on the surface of Pt atoms. The cell performance could not be completely recovered after purged with clean air and cyclic voltammetry (CV) tests, due to the changes of electrochemical impedance spectroscopy (ELS) and electrochemical active surface (EAS) caused by surface state change after SO2 exposure.