The influence of cell voltage on the performance of a pem fuel cell in the presence of hcl in air

The performance degradation is probed for a proton exchange membrane fuel cell (PEMFC) exposed to 4 ppm HCl in air at cell voltages of 0.4, 0.5 and 0.6 V. While the steady-state cell current decreases by 90% for the cells held at 0.6 V, it only decreases by 17% when the cells are at 0.4 V. We hypothesize that Cl? poisoning is more pronounced at 0.6 V vs. 0.4 V due to increase in Cl? coverage of the Pt nanoparticle electrocatalysts as the cell voltage (and electrode potential) becomes more positive, implying chemisorption coupled to an electrostatic effect. Chloride coverage increases by ca. 30% as cell voltage increases from 0.4 to 0.6 V. Further losses are caused by a 12% decrease in Pt electrochemical surface area (ECSA) due to Pt dissolution to chloroplatinate ions, followed by growth and agglomeration of Pt nanoparticles.