Electrochemical filtering of CO from fuel-cell reformate

A proton exchange membrane fuel cell was used as a flow reactor for continuous preferential oxidation of CO over H-2 from 1.0% CO in H-2 under pulse-potential control. By varying the pulse profile (e.g., on-time, off-time, pulse potential) the CO and H-2 oxidation currents were varied independently. The improvement in faradaic selectivity between CO and H-2 oxidation results from the promotion of CO adsorption during the off (i.e., open-circuit) portion of the pulse. Therefore, during the on portion CO oxidation was preferred while the surface was covered with CO. (C) 2002 The Electrochemical Society.