Spatial proton exchange membrane fuel cell performance under bromomethane poisoning.

The poisoning effects of 5 ppm CH 3 Br in the air on the spatial performance of a proton exchange membrane fuel cell (PEMFC) were studied using a segmented cell system. The presence of CH 3 Br caused performance loss from 0.650 to 0.335 V at 1 A cm −2 accompanied by local current density redistribution. The observed behavior was explained by possible bromomethane hydrolysis with the formation of Br − . Bromide and bromomethane negatively affected the oxygen reduction efficiency over a wide range of potentials because of their adsorption on Pt, which was confirmed by XPS. Moreover, the PEMFC exposure to CH 3 Br led to a decrease in the anode and cathode electrochemical surface area (∼52–57%) due to the growth of Pt particles through agglomeration and Ostwald ripening. The PEMFC did not restore its performance after stopping bromomethane introduction to the air stream. However, the H 2 /N 2 purge of the anode/cathode and CV scans almost completely recovered the cell performance. The observed final loss of ∼50 mV was due to an increased activation overpotential. PEMFC exposure to CH 3 Br should be limited to concentrations much less than 5 ppm due to serious performance loss and lack of self-recovery. [ABSTRACT FROM AUTHOR]